Indeed.... leaving one to wonder what to do with sound isolation in presence of such an effect. Double drywall is surely going to make the panel more stiff, making it less of an absorber for low frequencies.

Advice I have gotten is to put double-drywall on the outside wall (and don't use one at all in front of concrete foundation wall). It doesn't work as well that way since it is not against the source of the noise but seems like an interesting compromise.

What do you think?

I guess I'd rather invest in the sound isolation and rely on corner bass traps for LF absorption. Of course, the corner bass trap may not be as effective at ultra-low frequencies, but I have a hard time seeing how you design your gypsum walls to have an optimal amount of LF absorption given the resonant issues of the wall panel, and the fact that your room may not even be able to fit 1/2 wavelength @20 Hz. In my opinion, it is in-calculable. But if someone with vast amounts of experience tells you it makes a positive difference, then I guess I would defer to their experience.

Hi folks,

Since this one expense is holding me from pulling all the triggers on my HT, I'm hoping I can get the attention of a Pro here. My post from the last page asking thoughts on my acoustician's suggested plan for my room:

http://www.avsforum.com/avs-vb/showthread.php?p=14572391#post14572391

knight427 makes a good point, Amir. Design the walls for maximum isolation and then use acoustical treatments for quality sound in the room. Then there is no conflict.

As a side project, you could devote your spare time to solving the equation of isolating/sound absorbing walls. :)

I guess I'd rather invest in the sound isolation and rely on corner bass traps for LF absorption. Of course, the corner bass trap may not be as effective at ultra-low frequencies, but I have a hard time seeing how you design your gypsum walls to have an optimal amount of LF absorption given the resonant issues of the wall panel, and the fact that your room may not even be able to fit 1/2 wavelength @20 Hz. In my opinion, it is in-calculable. But if someone with vast amounts of experience tells you it makes a positive difference, then I guess I would defer to their experience.

My recepie is staggered studs that are liquid nailed to a concrete wall with felt on the studs between the 1/2" wall at a specific height. I also have a partition wall on the other side that is 1/2" DW, R19 pink, then 5/8 DW in the front of the room. The back of the rooms walls are 1/2" with R14 same as the other walls. My walls are not weight bearing and nothing in the room is attached to them including the ceiling. The partition wall is also offset. That is my isolation/walls.

My seats all measure practically the same. Here is -10dB at my worst seat.

http://farm4.static.flickr.com/3228/2825334958_5d0faa11de_o.jpg

Do you see anything wrong with what I did? Sounds great.

That is ok knight427. Nobody has commented on that one in years.

Hey Steve,

I browsed through some of your pictures trying to get a better idea of your design. Sounds like you did box-in-box construction.

I saw some of the comments on your photos where it appears you did a vibration survey of the studs before mounting the gypsum. What exactly did you do to treat these areas of vibration?

You also mentioned "felt on the studs between the 1/2" wall at a specific height". I'm not sure what you meant by this, nor am I familiar with using felt as part of an isolation system. Perhaps you can elaborate more on what you did, and why you did it.

Finally, what are the dimensions of your room?

Yes, it is both. Gypsum will reflect mid and high frequencies, but absorb a fair amount of low freq due to panel vibration. I'd go with carpet since all your other surfaces are hard.

Thanks!

I'll step in and say that the drapes will allow low frequencies to pass through with minimal absorption, then hopefully those lower frequencies will get absorbed by the panel (given sufficient thickness and density). You'll get more Abs/$ if you seperate the drapes and panels, but you'll get more balanced absorption across the frequency spectrum if you stack them.

I'm not clear what you mean by "seperate the drapes and panels" vs. "stack them." Sorry if I'm not understanding something simple, but would you mind explaining this to me?

Thanks!

Yes the superchunks are superior.

Wow, I was just going to ask which was the better option. Thanks for asking the question Pepar and thanks for answering it SteveMo.

When putting superchunks in a corner, is there a minimum size that they need to be? I'm thinking about trying to create something like the photo below from floor to ceiling. I have a 6" ledge about half way up the wall. I was planning to use 17" x 17" x 24" chunks on the top half of the wall and then small triangles on the bottom half to account for the 6" ledge. Is this an acceptable size (FYI, the room is approx. 9.5' x 17.5').

BTW, can anyone point me to some step-by-step directions showing how the fabric might be attached in a corner setup like the one below?

Thanks!

http://forum.studiotips.com/download/file.php?id=4456

I'm not clear what you mean by "seperate the drapes and panels" vs. "stack them." Sorry if I'm not understanding something simple, but would you mind explaining this to me?
Thanks!

By "stack", I meant put the drapes in front of the panels. Then separating them just means to hang the panels and drapes in different locations so there is no overlap.

Wow, I was just going to ask which was the better option. Thanks for asking the question Pepar and thanks for answering it SteveMo.

When putting superchunks in a corner, is there a minimum size that they need to be? I'm thinking about trying to create something like the photo below from floor to ceiling. I have a 6" ledge about half way up the wall. I was planning to use 17" x 17" x 24" chunks on the top half of the wall and then small triangles on the bottom half to account for the 6" ledge. Is this an acceptable size (FYI, the room is approx. 9.5' x 17.5').

BTW, can anyone point me to some step-by-step directions showing how the fabric might be attached in a corner setup like the one below?

Thanks!

http://forum.studiotips.com/download/file.php?id=4456

How much is it gonna cost you to do the superchunk thing?

link to original post

I felt compelled to provide some citation for my explanation of how sound absorption works. The following is the best I could find for now. It does not specifically support my claim that the absorber must occupy some space away from the wall because it needs to interact with molecules in motion (or “velocity zone” as I called it), but I think if you put the two paragraphs together, it essentially says the same thing.

All typos are my own, I hope this much text falls under fair use.

Handbook of Acoustical Measurements and Noise Control
Third Edition
Cyril M. Harris

Chapter 30
pgs 30.1-30.2

The element which accounts for the dissipation of sound energy in most acoustical materials is a layer of highly porous material (at least ½ in thick) in which the pores intercommunicate throughout. The pores may be formed by felted mineral or fiberglass, by the interstices between small granules, or by a foamed composition in which the solidified bubbles interconnect throughout the material. When a sound wave enters the porous material, the amplitude of vibration of the air molecules is progressively damped out by friction against the surfaces of the fibers or particles forming the porous structure. This friction acts as an acoustical resistance whose value depends on the resistance of the material to direct airflow; such friction depends only slightly on frequency.

Another factor which affects sound absorption, principally in the low-frequency range, is the depth of airspace between the face of the material and a rigid backing surface behind it. The volume of air between these two surfaces includes both the air in the pores of the material and any airspace between the material and its backing. The latter may vary from zero, when the material is secured directly to a rigid backing, to 3 ft or more in the case of suspended acoustical ceilings. When the total depth is less than about one-fourth wavelength, the low-frequency absorption coefficient of the material decreases with decreasing frequency.

Hey Steve,

I browsed through some of your pictures trying to get a better idea of your design. Sounds like you did box-in-box construction.

I saw some of the comments on your photos where it appears you did a vibration survey of the studs before mounting the gypsum. What exactly did you do to treat these areas of vibration?

You also mentioned "felt on the studs between the 1/2" wall at a specific height". I'm not sure what you meant by this, nor am I familiar with using felt as part of an isolation system. Perhaps you can elaborate more on what you did, and why you did it.

Finally, what are the dimensions of your room?

There were alot of studs touching the concrete walls. I went around the room hammering on them and marking the places with marker. I also found that many of the 2X4's had a certain tone to them when hit kind of like a tunning fork. The frequency at which they vibrated was very familiar to me as my previous HT was a basement with 2X4 wall construction. This was the flanking noise I heard across my walls at just above ear level. I would end up watching the wall and tracking the vibration move horizontally to each corner in my room. I decided since I had not been able to use the wood I wanted and I knew that I was in for trouble, to secure every 2X4 directly to the concrete using the liquid nails. I could not get isolation clips or anything else such as green glue, so I put strips of felt about 4 feet high starting just bellow ear level, and ending at around 6 feet high. The drywall was not screwed in at these areas. The partiton wall for the room within a room went in mostly as planned but I have since modified it by moving the equipment closet door out of the HT, and into the lobby. This is how it got the different thickness wall on the other side. The area where the door was got 2X2's that attached to new 2X4's.

Besides the 2X4's being nailed together, they are all glued at every joint using painters caulk or silicone. All sconces, light switches, electrical boxes, and anything else inside the concrete structure got caulk also. There is caulk filled between the door and frame of the HT door as well. Any plywood got wood glue. Dozens of tubes.

The crown molding is attached using deck screws only except for the molding on the carpet which attached using Velcro except for one peice next to 2X4 I used slicone on. The basebord is attached using trim nails. My quarter round trim at the top of the wall where the carpet is (next to the crown molding) only a friction fit as so are the other ones next to my screen. They look nice and neat without holes in them.

Basically I anticpated everything in the room to resonate and vibrate uncontrollably. What I was wondering if somehow by leaving the walls so flexable, and everything else very solid, I did something wrong? It seems most people here want very solid heavy walls but occasionally add additional means to make them decoupled. Someone was telling me that walls in a concrete room are supposed to be flexable, but I wanted to see if I get an opinion on if my method was practical or not. The builder (place was a last minute thought that was built in weeks) removed them, but I put them back. I saw one in the wall next to a stud when I was redoing the closet area and there was no space between it and drywall.

The ceiling has no drywall but is instead a layer of steel and concrete, with a Ceilume tile attached to the joist using ceiling link. I filled the tiles using "back panels" which were desingned to add more absorption, but I found that not to work very well. I filled the front of the room with them (2 layers) with pink inside and they sound much better. The drop ceiling above in my garage rattles. So does the garage door opener, the shelves etc. Sconces outside the house, the deck, candy counter, dishes in the sink (with the door open) all rattle as well. I think I may have done a decent job of isolation. I was playing WOTW at 5:00am and didn't wake up anyone.:eek:

The concrete area is 20 X 20 X 8' 7". That is an aprox on the ceiling height. The room including the ceiling tiles (not relevant for LF) is 20' X 13' 6" X 7' 6". There is also room treatments.

When putting superchunks in a corner, is there a minimum size that they need to be? I'm thinking about trying to create something like the photo below from floor to ceiling. I have a 6" ledge about half way up the wall. I was planning to use 17" x 17" x 24" chunks on the top half of the wall and then small triangles on the bottom half to account for the 6" ledge. Is this an acceptable size (FYI, the room is approx. 9.5' x 17.5').

BTW, can anyone point me to some step-by-step directions showing how the fabric might be attached in a corner setup like the one below?

Thanks!
Follow the 4/29/08 link in my sig and then on to the StudioTip Forum link. There you will find design and construction information. As for attaching fabric, I believe that there is a step-by-step where you found the image.

I went for the 17x17x24 version of the SSC traps.

- Jeff

How much is it gonna cost you to do the superchunk thing?
I paid about $10-$12 per sheet in bulk for OC 703. Each sheet makes 1.3 lineal feet (16") of 17x17x24 SuperChunk trap. Check the link in my sig.

- Jeff

Couple of quick questions - (1) I have easy access to either Knauf EI-475 or EI-800 but they both have FSK. In making the SSC's for the bass traps, will the FSK be a problem or should I rip it off or find a different material?, (2) I will have an AT screen mounted to a false wall 2 1/2' from the front wall. As far as the front and side wall treatments, should I remove the FSK or just mount the FSK against the wall or again find another product?

Steve

Couple of quick questions - (1) I have easy access to either Knauf EI-475 or EI-800 but they both have FSK. In making the SSC's for the bass traps, will the FSK be a problem or should I rip it off or find a different material?, (2) I will have an AT screen mounted to a false wall 2 1/2' from the front wall. As far as the front and side wall treatments, should I remove the FSK or just mount the FSK against the wall or again find another product?
If you check here (http://www.bobgolds.com/AbsorptionCoefficients.htm), you will see the difference between FSK and un-faced. But that is for flat panels, not chopped into triangles. I don't recall seeing any SSC testing with facing. You could go on the StudioTips forum and ask.

For lining the false wall cavity, I would place the Kraft against the wall.

If you check here (http://www.bobgolds.com/AbsorptionCoefficients.htm), you will see the difference between FSK and un-faced. But that is for flat panels, not chopped into triangles. I don't recall seeing any SSC testing with facing. You could go on the StudioTips forum and ask.

For lining the false wall cavity, I would place the Kraft against the wall.

I have searched and searched and have not seen any mention of whether the facing would affect the results in any way for the SSC. I will go over there and ask. Thanks

Steve

Gotta bump my post again:


Hey folks,

I'm at the point where I have to decide how much money I have to throw at my HT project and have just received one design for acoustic treatments, from the acoustician I've been working with. I'm just looking for second opinions because this stuff is darned expensive!

Here is an overview of my room, with screen and speakers indicated:

http://img179.imageshack.us/img179/1261/roommodeltopviewoe5.jpg

Here is a view from the couch:

http://img151.imageshack.us/img151/9485/roommodelfrontviewrp3.jpg

The acoustician's design suggests re-building the whole screen wall behind the speakers, with acoustic paneling behind the screen, screen wall, and some low bass traps spread along the floor and over top the screen.

There is an additional suggestion of acoustic panels on the ceiling, filling in the area within the ceiling bulk-head. The general areas of the acoustic treatment are represented in blue:

http://img299.imageshack.us/img299/1908/roommodelacoustictreatmrd2.jpg

Here's an image from the screen wall, facing the back of my room:

http://img149.imageshack.us/img149/8276/roommodelbackofroomsz7.jpg

As the room stands now, the general issues I'm having are a bass lift from the speakers being near the screen wall/room corners and a bit of lumpiness (dips) in the mid-range.

Any opinions on this design for acoustic treatment? It's quite expensive and I'm wondering how much I need to do to get some decent level of benefit. Could I forgo having the whole wall re-done and use traps in the corners or whatever?

Thanks mightily.

Rich H

Rich, just a thought here, perhaps the reason that no one has offered a second opinion - not even after three bumps - is that your situation is too complex to render an opinion without taking measurements and/or getting into it on a level not possible on a forum and for free.

Just a thought.

- Jeff

In making the SSC's for the bass traps, will the FSK be a problem or should I rip it off or find a different material?

FSK is good for corner bass traps, but not for absorbers at reflection points. More here:

Density Report (http://www.ethanwiner.com/density.html)

--Ethan

Follow the 4/29/08 link in my sig and then on to the StudioTip Forum link. There you will find design and construction information.

Actually Jeff, it was the your "Pepar´s Home Theater Upgrade Project" website and the link I found there to the Studiotips SuperChunk page that made me aware of the "Superchunk" approach. Thanks!!

As for attaching fabric, I believe that there is a step-by-step where you found the image.

The only mention that I could find about attaching the cloth was here:

A light frame covered in cloth and mounted in the corner to cover the panels is then installed to finish off the look of the appliance. Or a series of face panels could be cloth covered and mounted over the stacked triangles to enlarge the volume of the device and provide the finished face.

I was hoping for something a bite more detailed. Are you aware of anything that might help an amatuer?

I went for the 17x17x24 version of the SSC traps.


So, the chunks on the top half of my wall will be 17" x 17" x 24". However, due to the 6" ledge on the bottom half of the wall, the chunks on the bottom half would only be about 6" x 6" x 9". Is this too small to be effective?

Thanks.

First off, I believe this is my first post here. I've been pursuing this thread for a bit, looking for ideas and some guides...and I'm hoping I can get some suggestions as to what pitfalls to look out for with my setup from those of you with more experience than me. My fiance and I just moved into this house a few months ago, and I'm focusing on the Home Theater setup. I'm at the point where my speakers should arrive soon, and I'd like to get a basic idea for treatment layout. I'm familiar with absorption and diffusion as I've built several from the old Decware plans. I still have some of my first Decware Bass Traps and Quadratic Diffusers I built 10 years ago, but I'm looking into making some OC703 absorbers and super chunks and maybe a few skyline diffusers.

Secondly, forgive the Paint drawing. I got really fed up with trying to figure out Room Arranger, and I whipped this up in 25 minutes (about how long I wasted just starting a room in Room Arranger). The drawing is somewhat scaled having whipped it up by eye. But it's close enough for Rock n Roll.

http://www.lonelyraven.zenfolio.com/img/v0/p1069609937-5.jpg

* EDIT: Drawing is up now!


So I'm working with an L Shaped Living Room Dining Room combo. I drew in the kitchen to the right of the main seating, because I have a very large opening cut between the kitchen and living room with 3 bar stools there (three circles behind big L shaped opening in wall). And open doorways between the living room and kitchen, and dining room and kitchen (bright green)

The X marks my seat on the big leather theater chairs with a small leather couch to the left. Behind the main seating is a stair railing and stairs down to the lower level and front door of the house.

The light blue on the left wall and right wall are Windows which will have blackout drapes completely blocking out light (going almost floor to ceiling).

The viewing wall has an 84" projection screen, two glass gear racks under the screen, and my Elemental Design Home Theater speakers. The black box on the left is a 36" X 36" folded horn.

I absolutely plan on testing the room and seeing how this Home Theater responds. I have the RAW program and a Mackie Mixer, and I already have a HTPC connection to my receiver. I just need to order the Behringer ECM 8000 online since I can't find it locally (wasted most of the morning looking locally).

As it stands now, I have a couple of concerns I figure I'll have to deal with.

1) Left Speaker too close to left Corner.

2) Wide open (asymmetrical) right half

3) I have major flutter echo front to back that is terribly obvious with just clapping.

4) limited subwoofer placement due to its size. Though I suppose I could put it on edge so instead of being 36" X 36" table, it would be a very tall and wide...something...

I don't expect a complete diagnostic of my room, just some tips as to what to look out for, and how to correct or at least tweak the problems I have with this room setup.

After reading up in the thread here, and reading on other people’s theater builds I'm thinking...

1) portable diffusers to left and right of mains to help make the room sound symmetrical

2) Super Chunks in front left, front right, and corner between dining room and kitchen.

3) If possible without making the room look trashy, Super chunks along the ceiling sides and rear and maybe some of the front.

4) cloud at ceiling first reflection point?

5) skyline diffusers or absorbers on huge open back wall behind main seating, and possibly on side walls under proposed spots for rear channels.

If this is too much of a post for this ongoing thread, I'll start my own, just say so and I'll take care of it. :D Any and all help is greatly appreciated!

How much is it gonna cost you to do the superchunk thing?

I'm not sure yet. I don't know how many I need and haven't figured out where i'm going to buy materials.

Any general rule re: the amount of bass trapping needed in a room?

I'm planning to build some superchunks from floor to ceiling in the two front corners and one rear corner (no room in the 4th corner - there is a door).

Will this be enough?

The next two locations, if needed, would be the front wall-ceiling edge and the edge where the ceiling drops down by 13" (see photo below).

http://www.ulgm.org/PublishingImages/IMG_0506.jpg

My room is about 9.5' x 17.5' (more pictures in post #3718).

The amount required will be determined by the room size, room construction, furniture, # of people, and usage of the space, It's difficult to get too much in most cases.

As a general rule of thumb, if you can do the front 2 corners floor to ceiling and deal with potential bass nulls off the rear wall, that's a good start and certainly never going to be too much. Then we have to deal with more specific things like SBIR, positional issues to assist with frequency response, etc.

Bryan

The amount required will be determined by the room size, room construction, furniture, # of people, and usage of the space, It's difficult to get too much in most cases.

As a general rule of thumb, if you can do the front 2 corners floor to ceiling and deal with potential bass nulls off the rear wall, that's a good start and certainly never going to be too much. Then we have to deal with more specific things like SBIR, positional issues to assist with frequency response, etc.

Bryan

Thanks Bryan. Can you elaborate on what you mean by "deal with potential bass nulls off the rear wall?" Do you mean corner traps in rear corner or more like a GIK Monster Bass Trap on the rear wall?

Also, do you see any value in making a trap in that corner where the ceiling drops down? It would end up being like a 12" x 12" x 17" corner trap. I could run it the full 9.5' width of the room. Are those dimensions even large enough to have an impact?

Thanks.

Actually Jeff, it was the your "Pepar´s Home Theater Upgrade Project" website and the link I found there to the Studiotips SuperChunk page that made me aware of the "Superchunk" approach. Thanks!!
Glad to help. I remember when I started planning my theater and devouring every enthusiast website I could find.

The only mention that I could find about attaching the cloth was here:

A light frame covered in cloth and mounted in the corner to cover the panels is then installed to finish off the look of the appliance. Or a series of face panels could be cloth covered and mounted over the stacked triangles to enlarge the volume of the device and provide the finished face.

I was hoping for something a bite more detailed. Are you aware of anything that might help an amatuer?
I think you are on your own. After all, this is a Do-It-Yourself project. You'll have to use a little ingenuity! FWIW, when I return to working on my theater, I am adding more SSC traps to the rear of the room which will be visible and therefore need to be "finished" and aesthetically pleasing. Maybe I can copy what you come up with? :)

So, the chunks on the top half of my wall will be 17" x 17" x 24". However, due to the 6" ledge on the bottom half of the wall, the chunks on the bottom half would only be about 6" x 6" x 9". Is this too small to be effective?
If you have the room (and $$$), you could go with the 24x24x34 version . . .

Anyone in the Chicagoland area (preferrably western suburbs) know where I can pick up some OC703?

Is there a listing or thread somewhere in the forums where we have mabey compiled information of good places to pick up OC703?

Anyone in the Chicagoland area (preferrably western suburbs) know where I can pick up some OC703?

Is there a listing or thread somewhere in the forums where we have mabey compiled information of good places to pick up OC703?
http://www.spi-co.com/servicecenterdirectory.cfm?state=IL

Anyone in the Chicagoland area (preferrably western suburbs) know where I can pick up some OC703?

Is there a listing or thread somewhere in the forums where we have mabey compiled information of good places to pick up OC703?
Not sure how close the location is to what you re looking for but I bought my 2 cases of OC703 24X48X2 from these folks.

http://www.risris.com/Contact-Us/

Glad to help. I remember when I started planning my theater and devouring every enthusiast website I could find.

Indeed! :)

Maybe I can copy what you come up with? :)

I'll certainly share if I come up with anything good. :)

If you have the room (and $$$), you could go with the 24x24x34 version . . .

So, I'm thinking 24x24x34 on the top half of the wall and 17x17x24 on the bottom half. Any reason this wouldn't work?

So, I'm thinking 24x24x34 on the top half of the wall and 17x17x24 on the bottom half. Any reason this wouldn't work?
Sure. Actually I was thinking the stack would be the 24x24x34 on top and keep that "line" to the floor notching out whatever is necessary to accommodate the encroaching ledge or whatever it is that protrudes.

http://www.spi-co.com/servicecenterdirectory.cfm?state=IL

Not sure how close the location is to what you re looking for but I bought my 2 cases of OC703 24X48X2 from these folks.

http://www.risris.com/Contact-Us/

Thanks guys. I've sent an E-mail to both to see who's closer and can give me a good deal on the OC703.

New Question that I've not seen come up exactly (Granted I didn't read every post out of 127 pages).

For OC703 diffusers, does the cover material have to be acoustically transparent? Or can I wrap in whatever cloth I like the looks of?

New Question that I've not seen come up exactly (Granted I didn't read every post out of 127 pages).

For OC703 diffusers, does the cover material have to be acoustically transparent? Or can I wrap in whatever cloth I like the looks of?
It only needs to NOT be reflective. But I used Guilford of Maine (GOM) acoustically transparent cloth.

Sure. Actually I was thinking the stack would be the 24x24x34 on top and keep that "line" to the floor notching out whatever is necessary to accommodate the encroaching ledge or whatever it is that protrudes.

Thanks!

BTW, here's another DIY project that me some ideas for covering up the absorbers (http://www.hometheatershack.com/forums/home-audio-acoustics/7758-corner-traps-finally-finished.html).

i have a question i hope someone could answer for me.
my first reflection point for my mains are leather couch one side, leather loveseat other.
what should i do about this?

i have asked 4 times i think.
was wondering.....

would it help to hang panels on the wall over the couches to absorb relections that might bounch off them. they are both right in the line of fire for my first refection points of my mains.
also would it be benificial to put cloth coverings over them, the couches.
in a perfect world i would move them, and hang panels where they are.
anybody know a solutions to this?

2nd bump
i am not a leper

i have asked 4 times i think.
was wondering.....

Do you have a diagram?

CJ

2nd bump
i am not a leper

move the couches out of the way. :p

I would cover them with an accoustic absorbing blanket or sumsuch.

2nd bump
i am not a leper

I've never tried this product (nor any acoustical treatment yet, for that matter :) ), but maybe this is what you are looking for:

http://www.realtraps.com/p_cover.htm

I'm thinking really simply but wouldn't the ugly bags of mostly water sitting on said couches while watching the movie absorb the sound well enough?

Also, I was looking at some really cool metal frames yesterday and I can't for the life of me find the website again. Does anyone have the link? They were decorative and had some designs cut into the frames.

...that would be salt water bags. :)

Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.

Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.

I assume it would help with higher freq. but not low, could be wrong of course.

Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.

I hope this isn't too brutal an answer but....

There are so many variables to take into consideration that your carpet idea is far from practical.

Of course, if you were to build, then test it and post your results it might make for an interesting read. But the first questions you will get are:
1) which carpet
2) what pile
3) what was the density
4) which manufacturer,
5) did you use the pad,
6) which pad, etc., etc., etc.

I mean really..... there are over a thousand different carpets out there when just looking at density, depth, loop/cut loop before they add dyes for color.

Answers such as "standard carpet" will not cut it.

Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.
But blackbelt, expensive and hard to find is all part of the suffering that we do for our art, er . . home theaters. :D

http://www.spi-co.com/servicecenterdirectory.cfm?state=MO

Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.

Yes I have tried carpet with cloth around it. There were also some tiles laying under it there. I tried using outdoor/indoor carpet. It was the plush kind not the stiff stuff. I put about a 15' X 5' roll in the front right corner of my room in the ceiling extending out into the length of the room. The results were not good.

Hmm thanks for the responses, and the info stevmo. I am just looking for something to try. I have seen the link for spi before but thanks again pepar. A local home theater store said that they use sound board with cloth material around it. I did not get a chance to listen to the room they had it in as they were changing things around the store. I might give it a try.

Hmm thanks for the responses, and the info stevmo. I am just looking for something to try. I have seen the link for spi before but thanks again pepar. A local home theater store said that they use sound board with cloth material around it. I did not get a chance to listen to the room they had it in as they were changing things around the store. I might give it a try.
"Sound board?"

Sound board is very expensive

Sound board is very expensive
OK, but what is it?

I think ( correct me if I am wrong) It is the stuff you put behind drywall for sound insulation. Really firm material black I think.

I think ( correct me if I am wrong) It is the stuff you put behind drywall for sound insulation. Really firm material black I think.
To look at it's specs, we'd need to know the manufacturer and product name.

It is a product I found at an insulation sales store. They said they sold it to manufactor facilities and they wanted around $150.00 a sheet. It is the industrial equivalant to acoustimat.

hooray, I just found some John Mansville with the foil backing locally for $7.20 a sheet. Time to do some bass traps. :D:):p

I plan on 4" corner traps and 1" reflection traps. Is that ok? Is 1" enough?

Never mind, I figured it out.

hooray, I just found some John Mansville with the foil backing locally for $7.20 a sheet. Time to do some bass traps. :D:):p

I plan on 4" corner traps and 1" reflection traps. Is that ok? Is 1" enough?

Never mind, I figured it out.

I got a car load of the John Mansville 814 I think it was. $1 a square foot for the 2" stuff.

I'm still looking for cloth I like to wrap these in...or maybe just wimping out and buying some of the pre made bags...but I'd much rather do something custom.

I got a car load of the John Mansville 314 I think it was. $1 a square foot for the 2" stuff.

I'm still looking for cloth I like to wrap these in...or maybe just wimping out and buying some of the pre made bags...but I'd much rather do something custom.

Save your money and make your own. I've seen some premades for like $25 a piece.:eek:

Do you have to use oc 703? Or will any r-? insulation do? faceless or not?

Do you have to use oc 703? Or will any r-? insulation do? faceless or not?Everything absorbs/reflects sound differently. Thickness and density makes a difference as well. Your questions do not lend themselves well to a yes or no answer because there are so many variables in play.

Here is a list of products that have been tested and their coefficients.
http://www.bobgolds.com/AbsorptionCoefficients.htm

Those "Foam by Mail" people are really sad. Getting a shill to jump in here and shout how great their cheap foam is, in their one and only post on the whole forum.

Well, I have been following this and other threads for a long time and have been reluctant to take the plunge because it seemed complicated to get it right and the cost was too much especially looking at off the shelf products. I liked the look of the studio foams like Sonex and Aurelex but the cost to treat my room was approximately $800. I saw several comments on here that the cheap foam does not work, B.S. I bought foam from the foam factory on e-bay and installed 8 bass traps in (2) 8 ft columns in the front of the theater and 54 1 foot sq. 3" wedges at all of the FRP's and the results were dramatic. The sound improved so much that my 7 year old and my wife both described the sound improvement much the way I heard it. I am extremely happy and all for $140 delivered to my door. Thanks for all of the info I guess all I am trying to say is it is not as complicated as it may seem.

Rich

Do you have to use oc 703? Or will any r-? insulation do? faceless or not?
It's not the "R". Check 703's absorption coefficients here (http://www.bobgolds.com/AbsorptionCoefficients.htm) and then compare to whatever else you are considering. Some go more dense than 703. I don't recall anyone going less dense. Faced sheets are listed as well.

wierd how john mansville whispertone is 6pcf has less absorbtion in the 125hz range as the IS Black which is only 1.5pcf.

119530

wierd how john mansville whispertone is 6pcf has less absorbtion in the 125hz range as the IS Black which is only 1.5pcf
At some point it becomes too dense.

At some point it becomes too dense.

Could you elaborate? That seems strange to me. Are you saying that it starts to reflect the sound wave instead of absorbing it?

Could you elaborate? That seems strange to me. Are you saying that it starts to reflect the sound wave instead of absorbing it?

Well, if it doesn't absorb it, then it either transmits it or reflects it. If the flat panel is mounted on a wall and it transmits sound through to the wall, the wall will either absorb it, transmit it or reflect it, probably some of each. The transmitted sound is heard in the adjacent room and the reflected sound goes back through the panel and back into the room.

Well, if it doesn't absorb it, then it either transmits it or reflects it. If the flat panel is mounted on a wall and it transmits sound through to the wall, the wall will either absorb it, transmit it or reflect it, probably some of each. The transmitted sound is heard in the adjacent room and the reflected sound goes back through the panel and back into the room.

Some people are making super chunk corner traps with OC703/705. If their wedges are 17x17x24, then the thickest part of the trap in the middle is 12". If you say that at some point the OC becomes too dense, then these super chunks are a bad idea?

Some people are making super chunk corner traps with OC703/705. If their wedges are 17x17x24, then the thickest part of the trap in the middle is 12". If you say that at some point the OC becomes too dense, then these super chunks are a bad idea?
No, they are a great idea and more effective than most commercial traps. At some point, the fiberglass is too dense and will not be as effective at absorbing. Neither 703 or 705 fall into that category for chunk traps though. Bob Gold's chart is not for chunk traps. In the StudioTips Forum on SSC traps there is comparison data on sheets straddling the corner and the chunk style.

Thanks for the links and info. All.

Some people are making super chunk corner traps with OC703/705. If their wedges are 17x17x24, then the thickest part of the trap in the middle is 12". If you say that at some point the OC becomes too dense, then these super chunks are a bad idea?Density is not the same thing as thickness.

Density is not the same thing as thickness.

I knew that, stupid of me.

BTW, one of my corners is next to a door. I only have 12" from the wall to the door so a normal piece of 2'x4' will be too big. Will it hurt too much to make the trap smaller so that it doesn't interfere with the door or should I just live with it?

BTW, one of my corners is next to a door. I only have 12" from the wall to the door so a normal piece of 2'x4' will be too big. Will it hurt too much to make the trap smaller so that it doesn't interfere with the door or should I just live with it?Depends on which way the door opens. ;)

Depends on which way the door opens. ;)

The door will open just fine as it opens to the back bedroom. So would making the trap smaller hurt its effectivness too much?

The door will open just fine as it opens to the back bedroom. So would making the trap smaller hurt its effectivness too much?I meant: Does it open in or out. In any case, if it is a superchunk, I would not make it smaller since the depth is the most important parameter for the bass. I would cut the protruding corner at the door, if absolutely necessary.

The door will open just fine as it opens to the back bedroom. So would making the trap smaller hurt its effectivness too much?
It's probably better to put a trap there even if it is not the full profile (within reason) than to not have one there at all. Post a sketch of the full triangle w/dimensions and then show the reduction for the door.

Also, wall-to-wall corners are not the only corners in your room . . .

In the StudioTips Forum on SSC traps there is comparison data on sheets straddling the corner and the chunk style.

Do you happen to have a link?

Thanks,
CJ

http://forum.studiotips.com/viewtopic.php?f=8&t=536

Thanks!

CJ

Have there been any tests or studies on the difference in absorbtion at LF with a Super Chunk pressed up to the wall vs leaving say a 1" or 2" space between the chunk and the wall?

Has anyone compared a solid LF absorber like the Decware C.W.A.L. (I think that's the name for the Decware bass trap) vs a Super Chunk?

Have there been any tests or studies on the difference in absorbtion at LF with a Super Chunk pressed up to the wall vs leaving say a 1" or 2" space between the chunk and the wall?

Has anyone compared a solid LF absorber like the Decware C.W.A.L. (I think that's the name for the Decware bass trap) vs a Super Chunk?
The only comparisons that have been done are the ones at the link. Being a DIY product with no company making any money on them, there is no commercial backing for testing. In fact, I imagine that no commercial trap maker wants their products going anywhere near a test against SSC traps.

Here is what I bought. This is all I could find local. How does 4" corner traps, not super chunks, and 1" wall panels look?

119586

looks like 100% absorption at 1000hz.

Here is what I bought. This is all I could find local. How does 4" corner traps, not super chunks, and 1" wall panels look?

119586

looks like 100% absorption at 1000hz.
Lower would be better.

Lower would be better.

So I should go 2"? 100% absorption at 250hz.

So I should go 2"? 100% absorption at 250hz.
Yes, much better. What traps? 4" panel(s) straddling the corners?

Yes, much better. What traps? 4" panel(s) straddling the corners?

Yes. I think the superchunks are gonna cost too much.

Yes. I think the superchunks are gonna cost too much.
Understood. That type works quite well and is much less $$$ than filling the triangle. Just make sure that the edges of the panels touch the walls.

The only comparisons that have been done are the ones at the link. Being a DIY product with no company making any money on them, there is no commercial backing for testing. In fact, I imagine that no commercial trap maker wants their products going anywhere near a test against SSC traps.

I have heard that before (about going up against the SC).

Well, I have two of the Decware bass trapes. They are only 6' tall, so it wouldn't be fair to test against a floor to ceiling Chunk...but once my speakers show up and I can start doing some testing, I'll see what happens with two Decware traps vs two Chunks of equal size.

What interests me is that the Decware bass trap is solid, and the build directions state that alternating acoustic insulation with air (in the case 1" bubble wrap) causes it to reach deeper than just acoustic insulation.

Just food for though. I have no idea if this is true or not, and my theater setup isn't going to be ideal for testing...

I have two of the Decware bass trapes. They are only 6' tall, so it wouldn't be fair to test against a floor to ceiling Chunk...but once my speakers show up and I can start doing some testing, I'll see what happens with two Decware traps vs two Chunks of equal size.

What interests me is that the Decware bass trap is solid, and the build directions state that alternating acoustic insulation with air (in the case 1" bubble wrap) causes it to reach deeper than just acoustic insulation.

Just food for though. I have no idea if this is true or not, and my theater setup isn't going to be ideal for testing...
Do you have a link? I am on the Decware website and the only acoustical treatments I can find are diffusors.

Does anyone else have DIY Helmholtz Resonators? Is anyone interested in seeing results of a couple of them? I'm about to fill some with insulation.

Does anyone else have DIY Helmholtz Resonators? Is anyone interested in seeing results of a couple of them? I'm about to fill some with insulation.


Uhmmm........ this is an acoustical treatment thread.... of course we're interested. :) Yes, please post your results.

Will do then.

The audience is growing impatient so not much time to go into details at this time. There are two 12" woofers in the left front corner and two 12" woofers in the back right corner.

This is a measurement from yeterday night I did at the same location. I did not calibrate the SPL but turns out to be a 75dB target with speakers small, 80dB large on my XA2 with DVE. No equalization with all of these.

http://farm4.static.flickr.com/3030/2854208301_d3d7dfa743_o.jpg

Animation of opening a Helmhotz Resonator and filling with pink. The second was then opened and filled. Then both access areas were sealed with plywood and the covering and couch went back for the final pic. Measurements were taken in the front row, but there is a larger difference in the back row. The bass in the room becomes more even in all areas.

http://farm4.static.flickr.com/3154/2854199735_a4c124238f_o.gif

End result with 80dB calibration.

http://farm4.static.flickr.com/3254/2855043106_6c609672b9_o.jpg

I'm planning to build some superchunk corner bass traps. For aesthetic reasons (there is a ledge and some molding), I'm looking at having a 3" break in the trap about half way up the wall. Is this a problem for any reason? (FYI, I'm also planning some additional traps in one of the back corners and the front wall-ceiling corner.

Thanks.

Do you have a link? I am on the Decware website and the only acoustical treatments I can find are diffusors.

Looks like Decware no longer sells plans for the old style diffusers and absorbers. I happened to find my blueprints for them just the other day, so when I have time I'm going to review them a bit and see if I can glean any more information off them.

Doing a little Googling, I found this page:

http://www.decware.com/achowto.htm

Which has a few photos of the diffusers and absorbers that look exactly as I built. The bass traps are the big coffin like devices. Basically imagine a corner trap 6' tall, completely enclosed, and filled with alternating layers of acoustic insulation and bubble wrap. The insulation recommended was Thermafiber (don't recall which model but I'll figure it out as I still have 10 sheets in storage).

The Decware stuff was my introduction to room treatment. The bass trap made a huge improvement to my little apartment living room theater. So they do *something*, but I'm wondering if they do as well as Super Chunks. So I'll do some testing as I get my setup together (hopefully later this week). I have my ECM8000, Mackie Mixer, Computer, and REW...I'm just waiting on speakers and I need to find my Rat Shack DB meter(and trying to learn the software).

I just found this old photo of my living room of the apartment I used to have. You can see some of the MDF bass trap in the corner, plus all my diffusers piled up on one wall behind the guitar amps. I sorta gave up the living room to aquariums so I just packed everything up till we got a house just recently.

http://lonelyraven.zenfolio.com/img/v2/p604694658-4.jpg

I'm planning to build some superchunk corner bass traps. For aesthetic reasons (there is a ledge and some molding), I'm looking at having a 3" break in the trap about half way up the wall. Is this a problem for any reason?
That won't be a problem. But maybe you could devise a way to not have the gap by running the trap continuously. Your edge trim would need to follow the irregularity of the ledge but, aesthetically, the continuous trap may be better.

Looks like Decware no longer sells plans for the old style diffusers and absorbers. I happened to find my blueprints for them just the other day, so when I have time I'm going to review them a bit and see if I can glean any more information off them.

Which has a few photos of the diffusers and absorbers that look exactly as I built. The bass traps are the big coffin like devices. Basically imagine a corner trap 6' tall, completely enclosed, and filled with alternating layers of acoustic insulation and bubble wrap. The insulation recommended was Thermafiber (don't recall which model but I'll figure it out as I still have 10 sheets in storage).

The Decware stuff was my introduction to room treatment. The bass trap made a huge improvement to my little apartment living room theater. So they do *something*, but I'm wondering if they do as well as Super Chunks. So I'll do some testing as I get my setup together (hopefully later this week). I have my ECM8000, Mackie Mixer, Computer, and REW...I'm just waiting on speakers and I need to find my Rat Shack DB meter(and trying to learn the software).
The corner traps look very similar to SSC traps except that they are movable and, as you pointed out, do not go from floor to ceiling. No way to know their performance compared to SSC traps without a comparison under the same test conditions. Have you ever see any test data?

The advantage that I see with a movable trap is that it is . . . movable. But the downside is that it cannot be integrated into the room structure. And with most rooms having base 1/2" - 3/4" thick base molding, it will have that gap between it and the wall. I mention that only as an aesthetic concern of mine, not performance. And that "sitting there" look is my objection to all commercially available traps.

Just my $.02.

Hello everyone.

I want to build some superchunks corner traps. I want them to be portable. Is there any plans of how to make them.

I am thinking of traingle end caps, then some 2x1 wood strips. Anyone have any good plans?

Thanks

That won't be a problem. But maybe you could devise a way to not have the gap by running the trap continuously. Your edge trim would need to follow the irregularity of the ledge but, aesthetically, the continuous trap may be better.

Thanks Pepar. I am planning to put some curtains on the top half of the wall that would hang down to the ledge (this would be partly to cover a window and partly for pure aesthetic reasons). Given this, I was thinking it would look odd for the traps to come out from under the drapes. However, I'm willing to give up a little bit of aesthetics if there is a good acoustic reason to do so.

Thanks for any thoughts.

Hello everyone.

I want to build some superchunks corner traps. I want them to be portable. Is there any plans of how to make them.

I am thinking of traingle end caps, then some 2x1 wood strips. Anyone have any good plans?
You'll be the first! All of the implementations of the SSC traps that I have seen have been "built in."

Ran into the nice folks at A/V RoomService at CEDIA. Looking on their web site, I found these nice set of links, showing a comparison of studio recording and then in treated and untreated room. Worth a quick listen for folks not knowing what they are solving for with traps and such :).

http://www.avroomservice.com/sounds/

Ran into the nice folks at A/V RoomService at CEDIA. Looking on their web site, I found these nice set of links, showing a comparison of studio recording and then in treated and untreated room. Worth a quick listen for folks not knowing what they are solving for with traps and such :).

http://www.avroomservice.com/sounds/Interesting, but from reading their descriptions, it seems that the rooms, in addition to having different acoustic treatment, may also have different construction, dimensions, etc. Would be more interesting if it were the same room with the treatments covered/removed.

Ran into the nice folks at A/V RoomService at CEDIA. Looking on their web site, I found these nice set of links, showing a comparison of studio recording and then in treated and untreated room. Worth a quick listen for folks not knowing what they are solving for with traps and such :).
Educating the consumer. What an insidious way for them to sell more products. :)

Pepar, Agreed on the aesthetics of the CWAL. And the directions did say that 1/2" gap improves performance. I'm just curious of being in a sealed box enhances the low frequency absorption. If it does, then I might just have to make an enclosed floor to ceiling version...imagine a super chunk inside one of these.

As for measurements...I did see some measurements back in the day, but they weren't published exactly. Just something shown to me while I was visiting their listening room.

elee, I did see someone made a portable super chunk. He did like you are imagining with a triangle top and bottom, held together with what looked like 1/2" dowel at the three corners, then wrapped in fabric. It looked like it was 4' tall so it would take two of them stacked to fill a corner.

That exact method was going to be my plan as well. I figured I'd use dowels drilled through the base and top piece, glued in for stability. Then I'd just trim out the corners of the insulation so it doesn't bunch up and show through the fabric. My ceilings are exactly 8', so I'm going to lose a couple inches making two of these to stack. Not a big deal I figure...but I want to be able to measure before and after and compare the super chunks to the CWAL and see how well they work.

Hell, if the CWAL holds it's own in the double digit frequency, I may just use a combo of CWAL with portable Super Chunk stacked. But I'm guessing that's asking too much of a bass absorber to reach down so low without being tuned specifically for a double digit freq.

Interesting, but from reading their descriptions, it seems that the rooms, in addition to having different acoustic treatment, may also have different construction, dimensions, etc. Would be more interesting if it were the same room with the treatments covered/removed.

I didn't read it as much as advertisement for their services but rather, what the difference is between the source and and a room with lots of reverbrations. And then ponder if the "treated" room is the sound folks would like better.

Agree that the more before and after tests, the better.

Lonely Raven, FYI, you directed your response above to me but I but it was actually AnthemAVM who asked about building portable super chunks.

My question was whether there was any major acoustic drawback to having a 3" break half-way up the wall in a corner superchunk?

Lonely Raven, FYI, you directed your response above to me but I but it was actually AnthemAVM who asked about building portable super chunks.

My question was whether there was any major acoustic drawback to having a 3" break half-way up the wall in a corner superchunk?
No performance "drawback."

See Floyd Toole's new book, Sound Reproduction. Available on Amazon.

See Floyd Toole's new book, Sound Reproduction. Available on Amazon.
Thanks, headed to Amazon right now.

And am picking up T. Holman's as well.

- Jeff

Thanks, headed to Amazon right now.

And am picking up T. Holman's as well.

- Jeff

Add me to that! I've read some of Floyd Toole's papers, great insite. I'm heading over to Amazon also.

Thanks!
Ray

Pepar, Agreed on the aesthetics of the CWAL. And the directions did say that 1/2" gap improves performance. I'm just curious of being in a sealed box enhances the low frequency absorption. If it does, then I might just have to make an enclosed floor to ceiling version...imagine a super chunk inside one of these.

As for measurements...I did see some measurements back in the day, but they weren't published exactly. Just something shown to me while I was visiting their listening room.

elee, I did see someone made a portable super chunk. He did like you are imagining with a triangle top and bottom, held together with what looked like 1/2" dowel at the three corners, then wrapped in fabric. It looked like it was 4' tall so it would take two of them stacked to fill a corner.

That exact method was going to be my plan as well. I figured I'd use dowels drilled through the base and top piece, glued in for stability. Then I'd just trim out the corners of the insulation so it doesn't bunch up and show through the fabric. My ceilings are exactly 8', so I'm going to lose a couple inches making two of these to stack. Not a big deal I figure...but I want to be able to measure before and after and compare the super chunks to the CWAL and see how well they work.

Hell, if the CWAL holds it's own in the double digit frequency, I may just use a combo of CWAL with portable Super Chunk stacked. But I'm guessing that's asking too much of a bass absorber to reach down so low without being tuned specifically for a double digit freq.

Thanks, didn't think of the dowels, I was thinking of using 1x2 strips at the corners, for a total of six.

Michael

Can anyone tell me if this Duct board will work for my acoustic panels.

http://www.certainteed.com/NR/rdonlyres/146430D1-21FF-4C44-9DBB-033FEEDBECEB/0/3034006ToughGardDuctBoardSpecSht.pdf

Thanks

Can anyone tell me if this Duct board will work for my acoustic panels.

http://www.certainteed.com/NR/rdonlyres/146430D1-21FF-4C44-9DBB-033FEEDBECEB/0/3034006ToughGardDuctBoardSpecSht.pdf

Thanks

It looks like your getting 100% absorption at 500hz at 2" thick and 77% at 1" thick. Should work good. I would definately do 2" though.

Two questions re: superchunck corner bass traps...

1. When building a superchunk corner bass trap (i'm using Roxul Rockboard 60), is it necessary for the triangle pieces to sit right up against the two walls or can there be a gap of 2" or 3" between the trap and the walls?

2. Is there a substantial difference between traps that are 24" x 17" x 17" and traps that are 34" x 24" x 24"? Both my floor space and budget are limited, so I'm really hoping to use the smaller triangles, but only if the tradeoff in absorption is minimal.

Thanks!

Two questions re: superchunck corner bass traps...

1. When building a superchunk corner bass trap (i'm using Roxul Rockboard 60), is it necessary for the triangle pieces to sit right up against the two walls or can there be a gap of 2" or 3" between the trap and the walls?

2. Is there a substantial difference between traps that are 24" x 17" x 17" and traps that are 34" x 24" x 24"? Both my floor space and budget are limited, so I'm really hoping to use the smaller triangles, but only if the tradeoff in absorption is minimal.
The 34's reach lower, but they are truly super-chunky and not everyone can tolerate them aesthetically. Consider the corner formed by the juncture at the wall and ceiling and install the 24" design there in addition to the wall-to-wall corners when you can.

With even one corner trapped you will be ahead of most home theaters.

Thanks Pepar. Any idea whether it matters if the trap actually touches the two walls, or can it sit out from the wall. I thought I read somehwere that there might be an problem with certain frequencies if there is a gap between the trap and the wall.

I am planning to do at least one wall-ceiling corner. I'm pretty sure this one will be hidden by a curtain, so the 34" x 24" x 24" design shouldn't be an issue.

Is there any value in a superchunk smaller than 24" x 17" x 17"? There is a corner formed about 2/3 of the way toward the back of my room where the ceiling drops down about 12". I was thinking about making a 17" x 12" x 12" trap to fill this corner. Is it worth it?

Thanks.

Thanks Pepar. Any idea whether it matters if the trap actually touches the two walls, or can it sit out from the wall. I thought I read somehwere that there might be an problem with certain frequencies if there is a gap between the trap and the wall.
I don't know about that for the "solid" trap, but the corner absorber that is simply a 24" x 48" x 2" panel straddling the corner needs to be touching the walls. FWIW, I have never seen a DIY SSC trap that wasn't built tight in the corner. I have seen commercial corner traps that sit out from the walls because of the base molding. Those manufacturers, no doubt, will tell you that a gap is OK/better. :)

Is there any value in a superchunk smaller than 24" x 17" x 17"? There is a corner formed about 2/3 of the way toward the back of my room where the ceiling drops down about 12". I was thinking about making a 17" x 12" x 12" trap to fill this corner. Is it worth it?
2/3 of the way back - is it a corner that is not one of the four room corners?

I have several questions.

Can I use diffusion in a small HT 17’ x 13’ x 8’ when sitting less than 8’ from the walls?

I am thinking about putting absorption on approximately 35% of my walls and ceiling space (not counting the floor space). Is this a good number? I don’t want to make my HT too dead. I will put bass traps in the corners and absorption on the sidewalls and ceiling (reflection points) and behind the speakers. What should I do on the rear wall – leave it alone, diffusion or absorption? I was thinking of putting diffusion on the rear walls until I read that some references think that diffusion should not be used in small rooms.

I will be using Rockwool (because it is economical and I can get it locally) in lumber frames covered with an acoustically transparent fabric. I will be using 1” x 4” lumber for the frames w/2” thick Rockwool except for the bass traps. I will mount the frames flat against the wall which will give me a 1.5” air gap behind the Rockwool (the room is small and I don’t have much room for air gaps). Do I need to put a back (fabric) on the rock wool? I was thinking that I would not need to put a back on the Rockwool since the frame is flat against the wall and I do not plan on disturbing the Rockwool. I will hold the Rockwool in place with small wood blocks screwed into the back of the frame. I will use 6" of Rockwool mounted in the front corners for bass traps. I can't mount bass traps in rear due to doors.

I would be grateful for any other suggestion.

I have several questions.

Can I use diffusion in a small HT 17’ x 13’ x 8’ when sitting less than 8’ from the walls?

I am thinking about putting absorption on approximately 35% of my walls and ceiling space (not counting the floor space). Is this a good number? I don’t want to make my HT too dead. I will put bass traps in the corners and absorption on the sidewalls and ceiling (reflection points) and behind the speakers. What should I do on the rear wall – leave it alone, diffusion or absorption? I was thinking of putting diffusion on the rear walls until I read that some references think that diffusion should not be used in small rooms.

I will be using Rockwool (because it is economical and I can get it locally) in lumber frames covered with an acoustically transparent fabric. I will be using 1” x 4” lumber for the frames w/2” thick Rockwool except for the bass traps. I will mount the frames flat against the wall which will give me a 1.5” air gap behind the Rockwool (the room is small and I don’t have much room for air gaps). Do I need to put a back (fabric) on the rock wool? I was thinking that I would not need to put a back on the Rockwool since the frame is flat against the wall and I do not plan on disturbing the Rockwool. I will hold the Rockwool in place with small wood blocks screwed into the back of the frame. I will use 6" of Rockwool mounted in the front corners for bass traps. I can't mount bass traps in rear due to doors.

I would be grateful for any other suggestion.

If your using 6" for bass traps in the corner, you can use the same amount of material and make 4' tall superchunk bass traps. Assuming the rockwool is 2'x4'.

It looks like your getting 100% absorption at 500hz at 2" thick and 77% at 1" thick. Should work good. I would definately do 2" though.

Step,
Thanks for the response, I'll use the 2"!:D

2/3 of the way back - is it a corner that is not one of the four room corners?

I included a photo below of the back of the room. As you can see, the ceiling drops down 12 inches and forms a corner. This is the area that I was thinking about filling with some 17" x 12" x 12" Rockboard triangles. Will it have any effect?

http://www.ulgm.org/PublishingImages/IMG_0506.jpg

I included a photo below of the back of the room. As you can see, the ceiling drops down 12 inches and forms a corner. This is the area that I was thinking about filling with some 17" x 12" x 12" Rockboard triangles. Will it have any effect?
I'm sure it would have some effect. Don't know how much though. FWIW, I'd do it if it were my room for aesthetics - to soften it visually. And I'd take whatever absorption I got in the process.

Just my $.02.

I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.

Wayne

Here is some pics of the end of day 1 building my superchunk bass traps. I have a question, as you can see the right has a door there. When I stick my head in that corner, the bass is practically nill. Probably has something to do with the door. Should I even worry about treating that corner? It seems like an LFE black hole.

120484

120485

120486

Here is some pics of the end of day 1 building my superchunk bass traps. I have a question, as you can see the right has a door there. When I stick my head in that corner, the bass is practically nill. Probably has something to do with the door. Should I even worry about treating that corner? It seems like an LFE black hole.
It's where LFE goes to die? :eek:

Did you listen with the door closed and before stacking fiberglass? Did you listen to the other corners?

It's where LFE goes to die? :eek:

Did you listen with the door closed and before stacking fiberglass? Did you listen to the other corners?

door closed, before stacking fiberglass. The corner that is getting the chunks definately had strong bass. The back right corner sounds good and the back left corner is facing the stairs going up. The front right corner also has a return air vent going into the a/c.

door closed, before stacking fiberglass. The corner that is getting the chunks definately had strong bass. The back right corner sounds good and the back left corner is facing the stairs going up. The front right corner also has a return air vent going into the a/c.
I guess room layout, doors and such could be the reason. You could place a stack there - loose - and see if it makes any audible difference. Being a corner, in spite of your observation, it has to help.

Interesting.

Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?

Just throwing this idea out there...if there is a null in a corner, that just proves that there is as much bass (if not more?) since it takes both positive and negative waves to make a null. So maybe it's *more* important to treat that null than it is to treat the loud corner?

Just thinking out loud. Especially since I have an L shaped room with open doorways, and I'm not sure which corners are going to be the important ones that *have* to be treated. I'm not sure I have the option to treat them all (both budget wise and aesthetically).

At this point, I'm thinking about throwing some money at one of the gurus here just to point me in the right direction. Something I recommend anyone do who can't measure a room (or in my case doesn't understand the measurements! LOL)

Interesting.

Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?

Just throwing this idea out there...if there is a null in a corner, that just proves that there is as much bass (if not more?) since it takes both positive and negative waves to make a null. So maybe it's *more* important to treat that null than it is to treat the loud corner?

Just thinking out loud. Especially since I have an L shaped room with open doorways, and I'm not sure which corners are going to be the important ones that *have* to be treated. I'm not sure I have the option to treat them all (both budget wise and aesthetically).

At this point, I'm thinking about throwing some money at one of the gurus here just to point me in the right direction. Something I recommend anyone do who can't measure a room (or in my case doesn't understand the measurements! LOL)

From my understanding, room treatments will not improve a null. Room treatments are there to help reduce boominess so the bass sounds tighter. So if you stick your head in a corner and the bass sounds louder or "boomier" then you need treatments. Nulls can only be eliminated by moving the sub or adding another sub.

Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?

Yes, bass traps work best where bass builds up. Then they have something to act on. More on that here:

Pink noise aids placing bass traps (http://www.realtraps.com/lf-noise.htm)

--Ethan

From my understanding, room treatments will not improve a null.

This is not correct. Bass traps reduce peaks, raise nulls, and reduce decay time.

--Ethan

From my understanding, room treatments will not improve a null. Nope. Nulls and peaks are caused by the same thing (interactions of reflected energy) with the peaks being additive (in phase) and the nulls being subtractive (out of phase). So, if one reduces the peaks by reducing the room's ability to sustain energy at that frequency, one also reduces the nulls at that frequency as a concomitant.

BTW, moving a sub or other source can have an ameliorating effect but, since it does not change the basic acoustics of the room, peaks/nulls will remain. It's just that the sub and/or the listener will not be in the same place.

Interesting.

Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?

Just throwing this idea out there...if there is a null in a corner, that just proves that there is as much bass (if not more?) since it takes both positive and negative waves to make a null. So maybe it's *more* important to treat that null than it is to treat the loud corner?

Just thinking out loud. Especially since I have an L shaped room with open doorways, and I'm not sure which corners are going to be the important ones that *have* to be treated. I'm not sure I have the option to treat them all (both budget wise and aesthetically).
Well, room resonances are at "zero" at a boundary (wall) and all room resonances are present in corners, so not hearing a boom in a corner, now that I think about it, would be expected. Depending on the frequency/wavelength, a distance from a wall is where the boom (or null) would occur. If you have a square/rectangular room without any openings or irregularities, I think a corner is a corner and choosing wouldn't matter acoustically which ones were treated. It might aesthetically though.

At this point, I'm thinking about throwing some money at one of the gurus here just to point me in the right direction. Something I recommend anyone do who can't measure a room (or in my case doesn't understand the measurements! LOL)
That is an excellent idea!

Yes, bass traps work best where bass builds up. Then they have something to act on. More on that here:

Pink noise aids placing bass traps (http://www.realtraps.com/lf-noise.htm)

--Ethan
I understand the metaphor, but it isn't correct, is it, that bass "builds up" in corners? There isn't more of it there than anywhere else, is it?

This is not correct. Bass traps reduce peaks, raise nulls, and reduce decay time.

--Ethan

BruceK at Hometheatershack.com seems to disagree somewhat. He said that you would need a massive bass trap to improve a null, but it would be too big to get it into the room.

BruceK at Hometheatershack.com seems to disagree somewhat. He said that you would need a massive bass trap to improve a null, but it would be too big to get it into the room.
I am with Ethan on this one. Bass traps reduce bass energy. Reducing bass energy reduces the magnitude of the waves bouncing around the room and the amount of interference, with "interference" being a frequency going in one direction meeting it's reflection traveling in, more or less, the opposite direction. Where both of those are at the top (or bottom) of their sine wave and out of phase, they cancel producing a null. Where both of them are at top (or bottom) of their sine wave and in phase, they add producing a boom. The null is destructive interference and the peak is constructive interference. If the waves meet and they are at zero, there is no peak or boom. They are ALL at zero at the boundaries, which is why there should be no boom (or null) in a corner.

Trapping bass smooths out both peaks and nulls equally. Don't know what BruceK is thinking.

Thanks for clearing those points up, Ethan and Kal.

I'm going to be working on trying to understand REW and my "L shaped" room acoustics better...and if I come up more confused than going into this, I'll probably be hiring someone to at least make suggestions for me.

This was much easier when I had an 11' X 16' room in my apartment! Blah!

I am with Ethan on this one. Bass traps reduce bass energy. Reducing bass energy reduces the magnitude of the waves bouncing around the room and the amount of interference, with "interference" being a frequency going in one direction meeting it's reflection traveling in, more or less, the opposite direction. Where both of those are at the top (or bottom) of their sine wave and out of phase, they cancel producing a null. Where both of them are at top (or bottom) of their sine wave and in phase, they add producing a boom.

Trapping bass smooths out both peaks and nulls.

I have a null at around 70hz so I will take another measurement tonight with my new superchunk corner trap and see if it helped any. I also have some peaks at 25hz and another at 40hz.

I have a null at around 70hz so I will take another measurement tonight with my new superchunk corner trap and see if it helped any. I also have some peaks at 25hz and another at 40hz.
Please report your observations.

They are ALL at zero at the boundaries, which is why there should be no boom (or null) in a corner.


You got this wrong again - velocity is zero at a boundary - pressure (what you hear) is at a max at the boundary - which is why it is the best place to hear all the modal booms. In fact for the fundamental mode it is the only place - only the higher modes have pressure peaks within the room. The only place to not hear a null at any frequency will be in fact - the boundary (though there may be response dips between modal frequencies)

It is indeed correct that a pure velocity trap would be so large to be unuseable if you tried to reach the pressure nulls (velocity max) within the room. So any bass trap that works in corners is not trapping maximum velocity - as that is physically impossible. But that does not mean some can say they do not work - they may instead be trapping just some of the velocity or even be a pressure trap or even converting pressure to velocity.

You got this wrong again - velocity is zero at a boundary - pressure (what you hear) is at a max at the boundary - which is why it is the best place to hear all the modal boom. In fact for the fundamental mode it is the only place - only the higher modes have pressure peaks within the room.
Thanks . . again. So, from where this all sprung, sticking one's head in a corner and not hearing any boom means a trap wouldn't have anything to trap there?

It just means that corner does not have that modal frequency. It is entirely possible that a rectangular room coupled to another rectangular room has different corners with different modal response - you cannot predict these rooms using simple spreadsheet calculations.

90% of where I put treatments in my HT is based on where I feel pressure, the other 10% is measurements.

90% of where I put treatments in my HT is based on where I feel pressure, the other 10% is measurements.
Are you running a sweep or listening to music/movie?

I currently play sine waves -30dB FS, and watch movies while sitting in places one would not normally watch movies, such as standing on chairs or sitting in the front of my room next to my stage. The less difference it makes the more difficult it becomes. It is really really difficult to improve my room now. I started my treatments with a DIY subwoofer in a room with no framing. I then got a newer subwoofer after drywall went up and some few treatments such as the Helmholtz Resonator etc.. and started with loud rave music and walking around feeling the drywall move. It moved in the corners about 2ft away so I based my traps on that. I was carefull not to make the traps absorb an area that I heard while standing in a corner. A lower frequency ringing actually sounds quite similar to waking to an alarm clock before you awake. If adding Quiet Batt does nothing to improve my right corner and if it makes my 55Hz null worse again as it did with insulation I will be putting nothing there, because as far as I am concerned my left and right side of the room sound and feel the same. Coincedently my back left corner is very similar. Now I am basing the treatments based on where removing my tile ceiling improves.. I was always tought subwoofer measurements cannot be trusted. I am finding that there is really no telling where a bass ringing in the room may be, because although it shows on my measurements on the right side of my front row seats, I only hear it standing in the front of my room. If anyone was to use the program I wrote to delay REW measurements until sitting in the seat, they would probobly find that they themselves absorb a null, or cause a peak. Now getting that to work in multiple locations that is something different. ;)

I will probably go ahead and treat both front corners with superchunks anyway cause it can't hurt right?

Last night I was playing some games and listening to music with my left superchunk in place and I could definately tell an audible difference. The left front speaker was placed directly in front of the chunk and sounded much cleaner and crisper. I'm also sure that it helped my subwoofer although I am not an audiophile so I couldn't say how much.

Would you guys say that corner bass traps is essential in practically every home theater with a basic rectangular room?

I will probably go ahead and treat both front corners with superchunks anyway cause it can't hurt right?

Last night I was playing some games and listening to music with my left superchunk in place and I could definately tell an audible difference. The left front speaker was placed directly in front of the chunk and sounded much cleaner and crisper. I'm also sure that it helped my subwoofer although I am not an audiophile so I couldn't say how much.

Would you guys say that corner bass traps is essential in practically every home theater with a basic rectangular room?

Yes should be good. You would not be asking if not.

yes should be good. You would not be asking if not.
+1

Attaching Acoustic Panels to ceiling......

I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.

Wayne
____________________________________________________________ _
No takers....no one has any suggestions? Surely there must be something that someone has used to attach these light panels to the ceiling without hardware...

Wayne

Speaking of ceiling mounting, anyone know of any how-to's for mounting a superchunk trap in a ceiling-wall corner?

Attaching Acoustic Panels to ceiling......

I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.

Wayne
____________________________________________________________ _
No takers....no one has any suggestions? Surely there must be something that someone has used to attach these light panels to the ceiling without hardware...

Wayne
I don't recall anyone attaching panels of any kind to a ceiling w/o fasteners. Small angle brackets are usually used and they can be painted to blend in with the ceiling. But I see your dilemma with not having a frame.

I understand the metaphor, but it isn't correct, is it, that bass "builds up" in corners? There isn't more of it there than anywhere else, is it?

There certainly is more bass in the corners. This is very easy to measure. Use REW and measure the response at the listening position and then again in a corner. Or just play THIS (http://www.realtraps.com/lf-noise.htm) bassy pink noise and move an SPL meter around.

--Ethan

BruceK at Hometheatershack.com seems to disagree somewhat. He said that you would need a massive bass trap to improve a null, but it would be too big to get it into the room.

Well, of course it depends on the frequency of the null. But your friend is wrong and doesn't understand the science. There are before / after graphs all over my company's web site showing peaks and nulls being improved with bass traps. Below is a perfect example, with obvious improvements in nulls from about 50 Hz and higher.

--Ethan

http://www.ethanwiner.com/misc-content/lab-ringing-both.gif

So, from where this all sprung, sticking one's head in a corner and not hearing any boom means a trap wouldn't have anything to trap there?

Yes, but what you hear depends a lot on the key of the music and what frequencies it contains. This is why measuring using REW or equivalent is always better than by-ear just listening. Also, if you move your speakers, or buy new speakers, or add/change a subwoofer, that can affect what frequencies get to various places in a room. My approach is to treat all available corners if possible.

--Ethan

Well, of course it depends on the frequency of the null. But your friend is wrong and doesn't understand the science. There are before / after graphs all over my company's web site showing peaks and nulls being improved with bass traps. Below is a perfect example, with obvious improvements in nulls from about 50 Hz and higher.

--Ethan



That is good news for sure.

There certainly is more bass in the corners.
And I have been disabused of the thinking that lead me to post what I did. :)

My approach is to treat all available corners if possible.

--Ethan
Yes, and I am limiting myself to posting only that succinct and sage advice.

Mine was not a very conrtrolled test from where I started to where I am but you can see my first measurments, and where I am currently with bass trapping added bellow. The frst one has one sub on the back center wall, and the newer one is four of the same sub up front on the floor.

http://www.avsforum.com/avs-vb/attachment.php?attachmentid=120685&stc=1&d=1222385541


http://www.avsforum.com/avs-vb/attachment.php?attachmentid=120686&stc=1&d=1222385541

Thanks, SteveMo. Wonder what was happening on the "before" at around 120Hz?

The first one had a crossover engaged and was measured with the mains on, the second one does not have a crossover and the mains were off. I have no means to test with a crossover unless I use sound out of my XA2 DVD player and observe with an RTA. I'm guessing the 120Hz area with the ringing was related to the mains, and having not covered the first reflection points because it went away when I did that.

Here is ETC of my left and right mains before, and more recently a measurement on a single main, which was positioned pretty close to where I have it now. I will be investigating both more after I am done with the ceiling.

http://www.avsforum.com/avs-vb/attachment.php?attachmentid=120694&stc=1&d=1222389803

I recall someone recommending not to have back-panels on my ceiling tiles after I ordered them. I have tried removing those and it causes a slight null at around 160Hz, it smooths out my response from 100Hz to 60Hz and it increases the response from 10Hz to about 25Hz. This is after removing almost a complete row of them from the sides of my room.

Should I continue to remove these?

Above my tiles there isn't much. There is a layer of pink stuff I put across the ceiling joist I put up in a few hours. Above that is steel and concrete. Two steel beams run across the room horizontally and there is gaps between those. I need insulation for the back of my room and I was considering taking all the insulation out of my ceiling and placing those in my back wall area that is not filled with insulation. Then I could fill the ceiling with something else somehow. I was thinking maybe some Roxul but I am not sure how to place it. Any advise?

http://farm3.static.flickr.com/2420/2327022133_a33811322e_o.jpg

http://farm3.static.flickr.com/2227/2327837234_2d622b7e13_o.jpg

So I have almost finished the new install of these back panels with tape around the edges and half layers of OC R19 in them. Excellent for knocking creapie crawlies off the house, but now that I have removed most of the insulation from most of the ceiling coverage there is lots of bass up there, and most of the bass just all sounds like a big explosion. I narrowed down most of the problem to my front wall ceiling/wall corner, and my rear ceiling/wall corner. In the front of the room it almost sounds like someone slamming a door above me. :eek:

The ceiling here is 20' L X 13.5' W and between the tiles and the steel is 15.5" or 13.5". The closest distance from the joist and the steel is 7". On the left side of the room between the joist and the wall is 3.5" filled with insulation, on the right side it is 8.5", with heavy PVC I made into tiles and on the back wall it is currently lightly filled and with some tiles I made out of cork board 6.5". There are two steel support beams running from the left to right (filled spaces above where gaps were with the steel using pink) side, and a projector hush box with a 4" flexable duct and panny ceiling fan that I have insulation around.

Which would be best? I have found good results with GIK 244 traps up there for example. Pink insulation batts are difficult to install, and don't seem to work well for my application. The height to the ceiling tiles is 7' 6".

- 8 cases (X6) of 24 x 48 x 2 inch Roxul AFB 2.5 pcf (use two 2" layers)

- 2 orders of R-19 x 24 in. x 24 ft. Quiet Batt (5.5" thick)
- order more later because having nothing in an area is not good? Will not sound right?

- 4 cases (X6) of 24 x 48 x 2 inch Rockboard 60 - more later?

Can I use a microfiber material as the cover to my superchunk bass traps?

I bought these curtains (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=300260079309)to cover up a window and I was hoping I could also use them to cover the "grills" that I am making for my superchunk bass traps.

If you don't mind them reflecting higher frequencies then yes.

Can I use a microfiber material as the cover to my superchunk bass traps?

I bought these curtains (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=300260079309)to cover up a window and I was hoping I could also use them to cover the "grills" that I am making for my superchunk bass traps.
I would not use material in acoustical treatments for which the manufacturer made no claims regarding it's suitability for that purpose. And even then I'd want to see the test data. Can't address your wanting to cover the windows because I don't know what your goal is there.

I would not use material in acoustical treatments for which the manufacturer made no claims regarding it's suitability for that purpose. And even then I'd want to see the test data. Can't address your wanting to cover the windows because I don't know what your goal is there.

There is no way that material is going to reflect lower frequencies.

There is no way that material is going to reflect lower frequencies.
That's true. And not in conflict with my position. :)

That's true. And not in conflict with my position. :)

So why do you care if he uses it on his superchunk?

As you can see in the attached picture, I'm working on the acoustical treatment of my theater. I'm at this point due to the help you guys have give me so far & I appreciate it. Just finishing up on the super chunk install and will need to order a little more OC 703 for the front wall.

My question is for the first reflection points on the side walls and the ceiling, should I make 1" or 2" 703 panels? Also, how big should the panels be? The room is 16X 25 with 9' ceilings. On my rear wall I only have one corner that I can put super chunks in. Should I do it or leave both rear corners untreated?

Thanks for your help.

As you can see in the attached picture, I'm working on the acoustical treatment of my theater. I'm at this point due to the help you guys have give me so far & I appreciate it. Just finishing up on the super chunk install and will need to order a little more OC 703 for the front wall.

My question is for the first reflection points on the side walls and the ceiling, should I make 1" or 2" 703 panels? Also, how big should the panels be? The room is 16X 25 with 9' ceilings. On my rear wall I only have one corner that I can put super chunks in. Should I do it or leave both rear corners untreated?

Thanks for your help.

2". The panels will be 2'x4'. In my HT, I will use 3 of these on each side for 2 rows of seats.

So why do you care if he uses it on his superchunk?
Well, it it does in fact reflect higher frequencies, is that what is best for the overall acoustics of the room? If in the rear corner, would they create first reflection points bouncing sound at the listeners? Those would be my questions.

As you can see in the attached picture, I'm working on the acoustical treatment of my theater. I'm at this point due to the help you guys have give me so far & I appreciate it. Just finishing up on the super chunk install and will need to order a little more OC 703 for the front wall.

My question is for the first reflection points on the side walls and the ceiling, should I make 1" or 2" 703 panels? Also, how big should the panels be? The room is 16X 25 with 9' ceilings. On my rear wall I only have one corner that I can put super chunks in. Should I do it or leave both rear corners untreated?

Thanks for your help.
Three corners are better than two. Have you considered the "corners" formed by the walls and ceiling?

Three corners are better than two. Have you considered the "corners" formed by the walls and ceiling?
Pepar, I have not considered the rear wall where the wall meets the ceiling. Should that also have super chunks?

Regarding the front wall, I want to keep down the fiberglass dust and was thinking about covering the entire front wall with a black breathable fabric. Any problems there?

Pepar, I have not considered the rear wall where the wall meets the ceiling. Should that also have super chunks?
It could. Your front wall/ceiling juncture has one. Whether or not it should depends on your room's acoustics. But I have heard it said that you can't have too many bass traps. FWIW, I'm adding some to the rear of my room in addition to what I have behind my false wall.

Regarding the front wall, I want to keep down the fiberglass dust and was thinking about covering the entire front wall with a black breathable fabric. Any problems there?
Nope. And if you are using an AT screen, you want the stuff behind it black or at least very dark.

Well, it it does in fact reflect higher frequencies, is that what is best for the overall acoustics of the room? If in the rear corner, would they create first reflection points bouncing sound at the listeners? Those would be my questions.

I'm definitely concerned about my choice now. :confused:

I will have a superchunk in at least one rear corner of the room.

Also, I was thinking that I could hide the broadband absorption/diffusion panels that I might be getting behind these curtains.

I was really hoping to match my curtain fabric with my superchunk grills.

Is there any way to tell whether these curtains will reflect higher frequencies? They're pretty thin... when I hold them up, I can see light through them.

Thanks for any help!

I'm definitely concerned about my choice now. :confused:

I will have a superchunk in at least one rear corner of the room.

Also, I was thinking that I could hide the broadband absorption/diffusion panels that I might be getting behind these curtains.

I was really hoping to match my curtain fabric with my superchunk grills.

Is there any way to tell whether these curtains will reflect higher frequencies? They're pretty thin... when I hold them up, I can see light through them.

Thanks for any help!

Cover your mouth with it and see how easy it is to breath thru.

Cover your mouth with it and see how easy it is to breath thru.
And remember to pull it away if you cannot breath. :)

Cover your mouth with it and see how easy it is to breath thru.

How easy should it be?

If I cover my mouth tight with the fabric and blow moderately, my breath does flow through the fabric.

And remember to pull it away if you cannot breath. :)

Good thing I read the rest of this thread before I tried! :)

Oh, and if anyone would be willing to offer their consulting services, I could easily mail you a small swatch of the fabric for a more informed opinion. Just PM me. Thanks!

OK ... I have tried to use sketchup to give a idea of what I am dealing with in trying to get some bass trapping in this room

sides at first reflection points will be oc703 or linacoustic

on the screen wall will be oc703 chunked in the corners ... speakers will sit in front of that with a audiotransparent enclosure ( did not draw that part )

the side soffits are filled with HVAC etc

but the back soffit is empty except for the projector

the notch out at the back in the soffit is the projector location ( did not turn out like it will in reality but you get the idea )

because of the doors at the back there is no good way to do any bass trapping down low so my question is ...

can I use the back soffit area for bass trapping ?

what I am thinking is to line it with MDF and fill with fiberglass and use audiotransparent material on either side of the projector location

good idea ? ... will it work ?

http://i433.photobucket.com/albums/qq54/ScruffyHT/HTSOFFIT2.jpg

How easy should it be?

If I cover my mouth tight with the fabric and blow moderately, my breath does flow through the fabric.



Good thing I read the rest of this thread before I tried! :)

Oh, and if anyone would be willing to offer their consulting services, I could easily mail you a small swatch of the fabric for a more informed opinion. Just PM me. Thanks!

Well, you should be able to breathe better with it than you can with a 100% cotton shirt. Cotton is no good for higher freq.

Well, it it does in fact reflect higher frequencies, is that what is best for the overall acoustics of the room? If in the rear corner, would they create first reflection points bouncing sound at the listeners? Those would be my questions.

Pepar,

A few pages earlier in this thread you mentioned that it would be OK to put my acoustic treatments behind drapes because "the drapes are already absorbing the higher frequencies."

However, this most recent conversation has me understanding that the drapes will reflect the higher frequencies.

Can you clarify for me? My whole plan is based on putting my treatments (broadband and bass) behind these curtains. I even have my wife bought into the plan. :)

Thanks for your help!

(I posted a specific thread with this but I may find more suggestions here)

I'm trying to improve on the acoustics in my open designed room (actually enclosed with curtain panels). I've covered the windows with heavy velvet drapes and light blocking shades (left side of room). I'm going to be ordering ATS Acoustics 24x48 4" thick panels (http://www.atsacoustics.com/item--ATS-Acoustic-Panel-24x48x4--1008.html) to place behind the four window coverings. Should I opt for the open backed design or does the glass not reflect lower frequencies?

Also, I'm considering ordering two additional 24 x 48" 4" thick open backed panels (total of 8") to lay sideways against the wall behind the true sub (it's used for sub 60 Hz because there's an MBM-12 nearfield). Does this appear to be a good option for bass trapping? Will it actually be effective for sub 60 Hz frequency absorption?

Next to the sub (see pic, in the right front corner of the room) there is a cabinet in the corner. I was thinking it could be used as a bass trap by removing the door, covering it with a DIY grill cloth/frame, and stuffing it with fiberglass batting. Am I on the right track with this idea or am I missing something?

http://img91.imageshack.us/img91/5040/basstrapcopyae2.jpg (http://imageshack.us)
http://img91.imageshack.us/img91/basstrapcopyae2.jpg/1/w1000.png (http://g.imageshack.us/img91/basstrapcopyae2.jpg/1/)

Cotton is no good for higher freq.

Could you clarify this? Do you mean that cotton absorbs HF, or reflects it?

Could you clarify this? Do you mean that cotton absorbs HF, or reflects it?

It reflects it. If you want to absorb high freq. then you need to use something highly breathable like burlap or muslin.

Pepar,

A few pages earlier in this thread you mentioned that it would be OK to put my acoustic treatments behind drapes because "the drapes are already absorbing the higher frequencies."

However, this most recent conversation has me understanding that the drapes will reflect the higher frequencies.

Can you clarify for me? My whole plan is based on putting my treatments (broadband and bass) behind these curtains. I even have my wife bought into the plan. :)

Thanks for your help!
The truth is that unless test data exists for a particular fabric, I have no certainty on what it does. My sense is that most fabrics either absorb highs or pass them. In either case that fabric would be OK for broadband absorbers. But I think that there are also fabrics that could reflect them, which takes me back to wanting test data.

On the other hand, if the drapes are pleated and reflective, the highs will be diffused. :)

- Jeff

It reflects it. If you want to absorb high freq. then you need to use something highly breathable like burlap or muslin.
Got some test data on that? :)

Cotton is no good for higher freq.

This would not be correct. Nylon, polyester, burlap or otherwise makes no difference. The differences between each fabric is not based upon the material...it is based upon the weave and weight.

Any thoughts on post # 3930 ? - it may get lost & forgotten in this myriad of posts or should I make a seperate thread for it ? Thanks

ScruffyHT - your best to make your own post for your question. My opinion of master threads or sticky threads is that they should be for general questions about common or best practices and materials and not for individual theater questions.

This thread would be 10% of it's size if we applied this criteria.... of course, it's just my opinion.

Also, I'm considering ordering two additional 24 x 48" 4" thick open backed panels (total of 8") to lay sideways against the wall behind the true sub (it's used for sub 60 Hz because there's an MBM-12 nearfield). Does this appear to be a good option for bass trapping? Will it actually be effective for sub 60 Hz frequency absorption?

Down to 60Hz? Probably. Sub-60Hz? Not much using 4" panels. You'll get some gains there if you increase the panel thickness to 6".

Next to the sub (see pic, in the right front corner of the room) there is a cabinet in the corner. I was thinking it could be used as a bass trap by removing the door, covering it with a DIY grill cloth/frame, and stuffing it with fiberglass batting. Am I on the right track with this idea or am I missing something?

That could work. It's a very small amount of surface area and volume so I'm not sure what kind of results you could expect, but in theory it should work.

Frank

ScruffyHT - your best to make your own post for your question. My opinion of master threads or sticky threads is that they should be for general questions about common or best practices and materials and not for individual theater questions.

This thread would be 10% of it's size if we applied this criteria.... of course, it's just my opinion.
People tend to post where they see activity. This thread stays active and therefore near the top.

I've decided to try two GIK 244 bass traps in my cluttered (damn furniture :-)) living room and ran some LF pink noise through my system to see about good locations. LP1 and LP2 were both reading 75 db. The front right corner was reading 81 db while the left front corner was reading 85 db. The rear left corner was reading 77 db and the rear center was reading 76 db while no treatments can be made to the rear right corner.

From the above it seems the front corners are the locations in need of treatment. But... My TV is located in the left corner, I think a trap will fit behind the HDTV/stand with some breathing room but will it still be effective being boxed in?

This would not be correct. Nylon, polyester, burlap or otherwise makes no difference. The differences between each fabric is not based upon the material...it is based upon the weave and weight.

So why the hell did I buy all that burlap when I could have just used some nice fabric like cotton or polyester?

Got some test data on that? :)

I thought it was common knowledge. Otherwise why would I need to buy burlap as has been suggested many times on this forum?

People tend to post where they see activity. This thread stays active and therefore near the top.

OK then ... before I post another thread asking the same question is there any opinion on my post #3930 regarding bass traps in the soffit ? :confused:


Thanks

OK then ... before I post another thread asking the same question is there any opinion on my post #3930 regarding bass traps in the soffit ? :confused:
Your drawing is confusing as well - unusual viewing angle, surfaces cut away. Sure, you could fill it with 703. I probably would not fill the entire width of the soffit, but keep it to the same width as the soffit around the rest of the room. For it to be effective though, the entire surface needs to be covered with AT material not just the "front."

I thought it was common knowledge. Otherwise why would I need to buy burlap as has been suggested many times on this forum?

Burlap makes great firestarter for your campfire - that is why wood bags are usually burlap. People suggesting it are expensing their expendable life for a few bucks a yard.

The more commonly suggested Guilford Of Maine FR701 is a polyester with a very coarse open weave much like most burlap. More importantly it is named after the fire resistance standard which should be considered just as important for your use to have that rating. Even though it has a burlap look - it also has a much softer feel. I suspect that WAF on both issues outweigh any bucks saved - and it is one of the best performing for acoustical transparency fit for absorber and speaker covers - so there really is no WAF tradeoff (other than it looks like burlap - so they will want to spend more)

Most organic materials are inherently flammable unless retardant is added - but beware that humidity can "soak" out the retardant requiring annual reapplication. You will find most acoustical fabrics are indeed polyester because it just melts itself out. This same standard is used for drapes because they are the same application - a vertical hanging of fabric that can easily spread a fire.

Here is a random google hit on the topic....fire depts are the first to see the horrific results of flammable fabrics. Before you say my house never burnt down so I will save the bucks - ask yourself why do we have fire depts then?

http://www.ci.pasadena.ca.us/fire/Prevention/flammablefabrics.asp

While they recommend tight weaves over loose weaves for improved flammability ratings - but that is not good for acoustics as it will reflect high frequency. Since it is so hard to balance that fire/acoustics tradeoff - this is why it is best to just buy GOM FR701 - the desired open weave with a good flammability rating.

Your drawing is confusing as well - unusual viewing angle, surfaces cut away. Sure, you could fill it with 703. I probably would not fill the entire width of the soffit, but keep it to the same width as the soffit around the rest of the room. For it to be effective though, the entire surface needs to be covered with AT material not just the "front."

Is it difficult to see the soffit ? ... I rotated the sketchup so you could see the room layout as well as the soffit ... not sure I could make it open on both sides like you suggest and pass the WAF :)

the question is ... bass trapping is ideal in the corners right ? ... but since I have 2 doors at the back of the room will putting a bass trap in the soffit be effective or should I be looking at utilizing the riser as a supplemental bass trap instead ( back of riser will be 5 feet from rear wall ... dimensions are 12'x6'X16" ) ... is it possible for the riser to be used for bass trapping to compensate for rear corner traps ?

I am concerned that having bass traps in only the front corners will create problems in the back

I thought it was common knowledge. Otherwise why would I need to buy burlap as has been suggested many times on this forum?
Where did you read that you should use burlap?

Is it difficult to see the soffit ? ... I rotated the sketchup so you could see the room layout as well as the soffit ... not sure I could make it open on both sides like you suggest and pass the WAF :)
Well, if the frequencies don't hit it, the trap will not absorb them.

the question is ... bass trapping is ideal in the corners right ? ... but since I have 2 doors at the back of the room will putting a bass trap in the soffit be effective or should I be looking at utilizing the riser as a supplemental bass trap instead ( back of riser will be 5 feet from rear wall ... dimensions are 12'x6'X16" ) ... is it possible for the riser to be used for bass trapping to compensate for rear corner traps ?

I am concerned that having bass traps in only the front corners will create problems in the back
To quote Ethan - or at least paraphrase him as I haven't bookmarked the page - bass hangs out in the corners, so that is the best place to, umm . . kill it. :eek:

Too bad your soffits contain HVAC ducts as that area would be perfect locations for traps. Do the corners that you can and you will be ahead of many people. One corner is better than none, two corners are better than one, etc.

Thanks ... is the use of the riser for bass trapping effective for helping out with the rear of the room since it is " close " to the back of the room and I am filling it with insulation anyway

Where did you read that you should use burlap?

It's all over this thread.

It's all over this thread.
I either missed it or, more likely, ignored it. I understand the resistance that some have to spending the money that GOM costs and that leads to members coming up with all sorts of bargain fabrics that they found at the hardware store or fabric shop. Some of them are real eye-rollers. :rolleyes:

Expensive as it is, GOM is designed for use in acoustical applications. Any fabric that isn't is a pig in a poke.

Sorry, but that's just the way it is.

- Jeff

I know it has been said before but a FAQ would be cool ... "most" theatres here are rectangular with 4 walls and either have a AT screen ( so certain process to follow there ) or standard fixed or roll down screen

example

screen wall - corner traps ( and how to make them including insulation and material to cover it ;)) also what insulation to use on rest of the screen wall

side walls - first reflection points ( link to first reflection program or description of mirror test )

rear wall - corner traps ... also maybe treated for reflections

ceiling/floor - first reflections

Risers as bass traps ( my current question ;):p )

How to use testing programs like Room EQ Wizard to get a baseline on your room and determine what else needs to be added and where

links to theatres here as examples of what correct setup looks like

I have seen the link to all the different types of insulation out there and the corresponding data but as far as I know the only ones that I know for sure will work in our applications are linacoustic( screen wall/first reflection ), OC703( screen wall/first reflection ), OC705( bass trapping ), R13/19 ( walls/ceiling/risers )
But there are many more brands that are available that can do the same thing that maybe cheaper/more accessable in your own hometown but I have no clue what the equivalent brand would be to the above as a example

what fabrics are commonly used for covering acoustic insulation and why

just a suggestion ;)

Scruffy, any member here with the depth and breadth of knowledge to put such an FAQ together is a professional who sells their consultation services and/or acoustical treatments. And the rest of us are reading a lot here and wherever we can and trying to sort through it all on our own.

OK ... lets plow ahead then :) ... any thought on the bass trap idea for he rear of the room using the riser ? ... is it possible ?

OK ... lets plow ahead then :) ... any thought on the bass trap idea for he rear of the room using the riser ? ... is it possible ?
As long as they are taken solely as "thoughts" and not expert advice . . .

I don't think an enclosed riser stuffed with 'glass will do much. It will do "something" because it will have some natural resonance. How much I do not have a clue. Not being in a corner, it would not be in the best place to trap bass.

FWIW, I built my riser so that it would vibrate. Actually, I built it with the top deck "sprung" in anticipation of installing a motion transducer. (You can find it being built in the link in my sig.) Imagine my pleasant surprise when I found that it resonated at around 25Hz with a very satisfying amount of excursion.

Wow, so your riser is working as an absorber around the 25hz range?? Nice!


Since my theater setup was too complex for anyone but a paid pro to comment on, and I'm on a budget (which is pretty much spent at this point) I figured I'd just forge ahead and let my ears and REW be my guide.

So I just thought I'd throw this out there for others to check out. I'm building a semi-portable Super-Duper-Chunk that I can pull and move to another corner, test, retest, then try again somewhere else. Unfortunately I have very limited locations, so it's more an exercise in woodworking/design and practice in REW.

But here is what I'm working on:

http://lonelyraven.zenfolio.com/img/v4/p20648003-4.jpg



http://lonelyraven.zenfolio.com/img/v4/p393723360-5.jpg



http://lonelyraven.zenfolio.com/img/v4/p80686630-5.jpg


It's maybe a bit overbuilt, but it's strong enough to be able to pick up, carry up two flights of stairs (boy, that was fun!), drop in a corner and take measurements. It's 48" tall, and made from all 3/4" parts cobbled together from scraps. In fact, the frame is made from 2 X 4 I ripped down and the base and top are actually two different boards left over from speaker cab projects that I've glued end to end to make larger boards. :D The insulation triangles are 34" face, the face of the cage is about 36" from corner to corner...it's a bit big and I should have trimmed it down, but I have a lot of space in this one corner. My plans include building it's twin to stack on top, and then a large grill that will velcro to the face of the twin base absorbers as many others have done with their Super-Chunks.

For those who mentioned about sub-traps helping with nulls, I completely agree. I did before and after tests last night, and I saw nulls and peaks in the 60Hz-80Hz smooth out...but only about 1.5db. Other frequencies...well, not really any change worth noting. Hopefully with the second half of this semi-portable SDC stacked in the corner, I'll get a full 3db of smoothing where I need it.

Next up will be some 4' X 4' free standing absorbers and some baseboard chunks (probably square rather then triangle), and I'm still working out if my rear wall should be diffusion or absorption to help with the flutter echo which is probably what's killing my response in the 500-900Hz range and again further up the audio scale.

Cool!

Lonely Raven- I've got some of what you are asking for in the beginning my my theater build.

CJ

I was confused as to what you were talking about...but then I saw all the research and links in your thread. WOW! That's a lot of info! You must have been researching for YEARS!

I have a suggestion for you about those movie posters, I'll PM you.

what are the thoughts about building superchuncks or using GIK tri traps?

I used the tri traps in the past, and didn't think they worked. Well I was wrong, and need some absorption for the bass in my room.

I am afraid the superchunks will lok like crap, as I am not a diy.

Anyone aware of a layman's "how-to guide" for using software to measure changes in my room acoustics as I add/move various acoustical treatments? Any inexpensive/freeware applications you reccomend? What type of mic would I need to take such readings?

Thanks.

Anyone aware of a layman's "how-to guide" for using software to measure changes in my room acoustics as I add/move various acoustical treatments? Any inexpensive/freeware applications you reccomend? What type of mic would I need to take such readings?

Thanks.

Wouldn't REW work for what you are lokking for?

I either missed it or, more likely, ignored it. I understand the resistance that some have to spending the money that GOM costs and that leads to members coming up with all sorts of bargain fabrics that they found at the hardware store or fabric shop. Some of them are real eye-rollers. :rolleyes:

Expensive as it is, GOM is designed for use in acoustical applications. Any fabric that isn't is a pig in a poke.

Sorry, but that's just the way it is.

- Jeff

Not sure what that means, but burlap will work just fine and no I don't have any test data.

Wouldn't REW work for what you are lokking for?

Thanks Anthem. Unfortunately, if I'm reading the requirements of REW correctly, a typical laptop soundcard is not sufficient (I have Lenovo X61 w/SoundMAX Integrated Digital HD Audio). Am I correct?

On the positive side, it seems I can use my SPL meter rather than having to buy some type of microphone.

I also looked at ETF, which sounds like it will work with my soundcard but costs much more than I can afford.

Any other reccomendations?

Not sure what that means, but burlap will work just fine and no I don't have any test data.
A "pig in a poke" is an idiomatic expression for something unknown, or taking a chance.

I don't think anyone said that burlap would not work.

Thanks Anthem. Unfortunately, if I'm reading the requirements of REW correctly, a typical laptop soundcard is not sufficient (I have Lenovo X61 w/SoundMAX Integrated Digital HD Audio). Am I correct?

On the positive side, it seems I can use my SPL meter rather than having to buy some type of microphone.

I also looked at ETF, which sounds like it will work with my soundcard but costs much more than I can afford.

Any other reccomendations?
Any "soundcard" with bi-directional capabilities will work. Laptops usually do not meet that requirement, in which case an external USB solution is needed. SoundBlaster has one as do many others.

Not sure what that means, but burlap will work just fine and no I don't have any test data.A "pig in a poke" is an idiomatic expression for something unknown, or taking a chance.

I don't think anyone said that burlap would not work, but some may have aesthetic objections to it.

Or fire/safety concerns and perhaps even code restrictions as well.

Or fire/safety concerns and perhaps even code restrictions as well.
I'm giving up on commenting on bargain materials members have found (or already bought). They are intent on using it anyway and don't to want to hear possible reasons why they shouldn't.

I'm giving up on commenting on bargain materials members have found (or already bought). They are intent on using it anyway and don't to want to hear why they shouldn't.Sounds like the wiser way to go. At least, less stressful anyway.

I was confused as to what you were talking about...but then I saw all the research and links in your thread. WOW! That's a lot of info! You must have been researching for YEARS!

I have a suggestion for you about those movie posters, I'll PM you.

I have been researching for years, but I only started putting links up for a few months. It amazing how much accessible information is out there once you start looking for it.

CJ

I'm giving up on commenting on bargain materials members have found (or already bought). They are intent on using it anyway and don't to want to hear possible reasons why they shouldn't.

As far as fire safety is concerned, I just don't see it. I'm sure there are lots of things in my house that could be flammable if someone tried to light it. Are you guys saying that it might spontaneously combust or something? Maybe i'm missing something, which is entirely possible.

Fire codes are about fire spread control - not about being flame proof - you would be amazed how fast burlap explodes into a fullout blaze - better fire starter than newspaper which flames out too quick. Polyester might just drip a bit before it flames itself out - for sure does not spread a fire.

There is a reason you don't see drapes made of burlap - ask your local fire chief who HAS seen it. Survival of the fittest - its your house and life- not mine.

If you don't care - buy a yard sample of each and lite it with a bic and see if the WAF cares.

Just a quick ? for you guys I am using 6" thick bass trap panels should I put them in all four corners of the room or just the front.

Just a quick ? for you guys I am using 6" thick bass trap panels should I put them in all four corners of the room or just the front.
Do as many corners as you can. I would start with the fronts.

Thanks. :)

Ok one more ? should I use 6" panels in the four corners of the room or 4" for bass absorption.

According to the posted numbers, 6" is better, but 4" is sufficient. Correct me if I'm wrong, but 17"x24" super chunks outperform a 6" panel for the same amount of materials used (Am I remembering this incorrectly?)

According to the posted numbers, 6" is better, but 4" is sufficient. Correct me if I'm wrong, but 17"x24" super chunks outperform a 6" panel for the same amount of materials used (Am I remembering this incorrectly?)
I used 2" x 24" x 48" to make my 17x17x24 SSC traps. One sheet made eight triangles which translates into 1.5 lineal feet of trap. A 6" x 24" x 48" sheet would make 4.5 lineal feet of that same size trap, but only 4 lineal feet of "trap" if used whole and straddling a corner. So, it makes more and is more effective as SSC trap. However, it is considerably more expensive per lineal foot of trap to use 6" over 2".

I used 2" x 24" x 48" to make my 17x17x24 SSC traps. One sheet made eight triangles which translates into 1.5 lineal feet of trap. A 6" x 24" x 48" sheet would make 4.5 lineal feet of that same size trap, but only 4 lineal feet of "trap" if used whole and straddling a corner. So, it makes more and is more effective as SSC trap. However, it is considerably more expensive per lineal foot of trap to use 6" over 2".

Exactly right...well put.

Frank

My room is not a dedicated room, but I do not see a better place to ask my questions regarding panel location. One end of my family room is set up for HT. All of my equipment is built into my front wall (see pic below). I am running a 7.1 system. I have RBH in-wall speakers for my front right, front left and rear speakers. My center channel is an RBH 661SE (cabinet speaker) and so are my side channel speakers. Not shown in the picture is my projection screen. Out to out of my screen is 8 feet so it lines up with the doors when they are open.

The width and depth of my room (end that I use) is not large, but since I use in-walls for most of my speakers the speaker distance is larger that what you would have for a small room. The end of the room that I use is 17' wide, 16' deep and I have a 17' flat ceiling (4,624 CF). One whole side is open (16' side). The whole room totals almost 12,000 CF and I have large crown molding at the ceiling. I have two large windows on my end of the room, one centered on the back wall (2nd pic) and another identical window on my side wall.

Much of what I have read has told me to cover as much of the front wall and back wall as posable. Then install panels at the reflection points on the side wall and panels or bass traps in the corners. Do the same rules apply with in-wall speakers? I am using 2"x24"x48" mineral wool, with wood frames covered with fabric. The frames are 2-3/4" of depth so that I have a 3/4" air space at the back of the panel.

Bass traps in the corners is out since this is a family room, but I could install a panel across the front right corner and the back right corner, but I would not want to stack a bunch of panels in these corners due to looks. Any and all suggestions direction is appreciated. Thank you.

http://i243.photobucket.com/albums/ff112/mjg100photo/P1000499.jpg

http://i243.photobucket.com/albums/ff112/mjg100photo/P1000506.jpg

Then install panels at the reflection points on the side wall and panels or bass traps in the corners. Do the same rules apply with in-wall speakers?

Yes, in-wall speakers also have reflections off the side walls and ceiling. In a very wide or tall room where the reflection points are far away, the reflections are weaker simply due to distance. But with your width I'm pretty sure absorption on the side walls will help.

--Ethan

Yes, in-wall speakers also have reflections off the side walls and ceiling. In a very wide or tall room where the reflection points are far away, the reflections are weaker simply due to distance. But with your width I'm pretty sure absorption on the side walls will help.

--Ethan
ugh. I really want to read through this thread as I am RIGHT at the point of buying my acoustical treatments to begin finishing up my walls, but man oh man I don't even know where to start in this thread. :confused: :eek:

Yes, in-wall speakers also have reflections off the side walls and ceiling. In a very wide or tall room where the reflection points are far away, the reflections are weaker simply due to distance. But with your width I'm pretty sure absorption on the side walls will help.

--Ethan

Thank you Ethan. Right now my plan is to install panels on my back wall since I am about 5 feet from it. My panels are 2.75" deep with 2" of rock wool and 3/4" air space at the back. I will also install this same panel on my side wall at all of the reflection points that I can hit. For the corners I will also use panels, except they will have 4" of rock wool. On my front wall I had planned on using the same panels (2.75" thick with 2" rock wool) as on my back wall. Only problem is I only have enough space for one or two panels, from the top of my screen to the floor. I have plenty of space above my screen, enough for seven panels.

The panels (2.75" thick with 2" rock wool) above the screen would be in the area between 9 feet and 16'-4" above the floor. Would panels that high help? Panels will not be used at the intersecting joint of wall and ceiling, but I do have large crown molding there.

My other question is in regards to the side wall. Since I have such high ceilings, would it help to stack two panels at the reflection points?

As to my ceiling, I was not too worried about reflections since it is so far away. I assume that the same rules regarding reflections apply to the ceiling that apply to the rear wall. Long distance, less of a problem. Besides my wife would not be too pleased if I placed panels over the crown molding.

Thank you,

Mike

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

pam

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

This is all Very good information, and comes to where I am. My room is 210 square feet, 15' x 14'. It is a low-ceiling room, and will end up being roughly 7' 4" in height once the ceiling and floor is in place. So does this basically mean that I am better served not putting up drywall at all and spending the money on some type of acoustical treatment for all my walls? I want it to sound very good (I'm spending a fair buck on speakers, screen and projector) but I do have a limited budget that I need to use putting the walls in, sealing up the room and applying the acoustical treatments.

I thought that I could use isomax isolation clips and put two layers of 1/2" drywall, and then make 2" thick, 24" x 56" panels to place at the reflective points, and then a couple of larger acoustical panels in the rear of the room.

I didn't realize that I needed to make the entire front wall dead as a doornail... Are there any relatively inexpensive solutions that I can apply to the surface of the drywall I intended to put up? I also have one other, major problem with the front wall - it's where the door to the room is..

Is there something I should and could do to help deaden the door? put panels on the back of it? Buy a wooden door?

bty, great thread. I'm only on post number 80, though. lol

ugh. I really want to read through this thread as I am RIGHT at the point of buying my acoustical treatments to begin finishing up my walls, but man oh man I don't even know where to start in this thread. :confused: :eek:

I am up to page 122. When you include reading the links it is a lot to read, but it has taught me a lot.

man oh man I don't even know where to start in this thread. :confused: :eek:

This thread is way too long and has too much contradictory information. My Acoustics FAQ (http://www.ethanwiner.com/acoustics.html) is very detailed, and while a lot to read it's much more manageable.

--Ethan

my plan is to install panels on my back wall since I am about 5 feet from it. My panels are 2.75" deep with 2" of rock wool and 3/4" air space at the back.

The wall behind you needs thicker absorption. You should use 4 inches thick minimum if possible.

Would panels that high help?

Sure, if that's where the reflection points are.

Since I have such high ceilings, would it help to stack two panels at the reflection points?

The size of the area covered is more a function of how far back you are from the speakers. They call it a reflection point but it's really an area.

--Ethan

This thread is way too long and has too much contradictory information. My Acoustics FAQ (http://www.ethanwiner.com/acoustics.html) is very detailed, and while a lot to read it's much more manageable.

--Ethan
Perhaps if you put it in the public domain it wouldn't make it seem like you are using this thread for selling.

Attaching Acoustic Panels to ceiling......

I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.

Wayne
____________________________________________________________ _
No takers....no one has any suggestions? Surely there must be something that someone has used to attach these light panels to the ceiling without hardware...

Wayne

Over the last several days I have read all of the posts in this thread and I recall reading about a guy that did just that. His ceiling was concrete so he used construction adhesive. If you are doing your whole ceiling you have several choices. You could run a 2" thick board around the perimeter of your room and run a 2" board across your room every 4 feet. Glue panels to the ceiling and use the 2" board to secure the fabric covering the ceiling.

You could grid your ceiling into slightly larger than 4' x 4' areas using a board 2-1/2" thick and use a 1" x 4" finished board on the bottom to make a ledge. Think upside down "T". This would hold up the 2" OC. Cover each piece of 2" OC with fabric. You could do this as a strip across the room rather than squares. You would need to screw or glue the middle of the panel so that it did not sag over time.

Added
You could glue a couple of small wood strips to the back of each 2" fabric wrapped OC panel and that should support each panel that sits on the "T" shaped ledge.

Over the last several days I have read all of the posts in this thread and I recall reading about a guy that did just that. His ceiling was concrete so he used construction adhesive. If you are doing your whole ceiling you have several choices. You could run a 2" thick board around the perimeter of your room and run a 2" board across your room every 4 feet. Glue panels to the ceiling and use the 2" board to secure the fabric covering the ceiling.

You could grid your ceiling into slightly larger than 4' x 4' areas using a board 2-1/2" thick and use a 1" x 4" finished board on the bottom to make a ledge. Think upside down "T". This would hold up the 2" OC. Cover each piece of 2" OC with fabric. You could do this as a strip across the room rather than squares. You would need to screw or glue the middle of the panel so that it did not sag over time.

Added
You could glue a couple of small wood strips to the back of each 2" fabric wrapped OC panel and that should support each panel that sits on the "T" shaped ledge.


One word: Rotofast! Get their cloud hangers and it couldn't be easier. I use four per panel and they work great. Plus they hang down about 2-3" from the ceiling, which I think provides even better acoustical treatment.

I spaced mine about 6" in from the long sides and one foot from the short edges. This seems to support them quite well, and no sagging after almost a year of hanging.

Yuk. This thread does seem to be an interesting discussion at worst, but man it is very long, and I quite frankly don't have enough time just to read this thread... So... I suppose I'm off to read some other stuff and see if I can make sense of what I need.

I have a small room, which seems to warrant more absorbtion than diffusion, and tonight my wife and I finally got everything laid out with regards to screen location and seating locations.

So I need to nail down my construction methods by the end of this week so I can being wiring up and getting the materials to build the walls.

So now I have a 14wx15dx7'h that has a door on the front wall. I'm offsetting all of the seating and screen so this is going to be an interesting delimina in how I handle the acoustics in the room... Especially since the main seating is black leather, with the listening/viewing position 11ft from the front wall, and there is going to be a small 'bar' (more like table) with bar stools for additional seating behind the main sofa seating, so I have a bunch of accoustical stuff to figure out, including where to put the speakers.

So... I'm off to figure out how I'm going to construct the walls, and the stage, and figure out where to place my in wall speakers. The fronts will be going behind a perforated screen, so treating the front wall is going to be critical to starting things off properly.

I live in upstate NY, and I'm thinking I'm going to need professional help calibrating my room and final determination of proper acoustic handling... Hopefully, I'll be able to find someone locally...

My home theater has an entrance door in one of the back corners. The room has 8’ ceilings and I am putting 8’ bass traps in the two front corners. My question is should I keep the base traps symmetrical or can I put a third bass trap in one of the rear corners and not the other?

Mike

My home theater has an entrance door in one of the back corners. The room has 8’ ceilings and I am putting 8’ bass traps in the two front corners. My question is should I keep the base traps symmetrical or can I put a third bass trap in one of the rear corners and not the other?

Mike
Do as many corners as you can. Assymetricity will not matter to the sound, only the eye. BTW, there are "corners" formed by the walls and the ceiling . . .

Perhaps if you put it in the public domain it wouldn't make it seem like you are using this thread for selling.

Not sure what your point is. My Acoustics FAQ is on my personal site, and intentionally has no "sales" content. It's also free, and I even answer support questions for free. How much more "public domain" could I make it? :confused:

--Ethan

OK. Starting from scratch with new construction. Left wall and front wall are ICF (insulated cement form) construction, back wall and right wall are 2x4 studs with sheet rock. Ceiling and non-icf walls insulated with R13. Screen wall is basic acoustically transparent fabric. Riser is 4" for first step with 10" after that filled with R13.

I have read this thread until my eyes hurt and everything now is clear as mud. Can someone explain to me in simple english terms (I'm not an acoustic techy by any means) what I need to do to my room for acoustic treatments. The rooms is 20' wide, 37' long and 8' ceiling. I have downloaded the Sweetspot from Guide to Home Theater and it said I may have 11 frequency zone issues. I don't want to spend a gazillion dollars just want a good sounding home theater. First row seating at 9', second at 15' and bar at 21' with 7.1 system. Denon, Klipsch with 50" Pioneer 5010.

Can someone help? I have looked into computer programs too and I am no techy at this either. I'm a meat and potatoes guy. I don't want to hire a home theater tech to design all of this either. Hope this isn't offensive to anyone.
RG

OK. Starting from scratch with new construction. Left wall and front wall are ICF (insulated cement form) construction, back wall and right wall are 2x4 studs with sheet rock. Ceiling and non-icf walls insulated with R13. Screen wall is basic acoustically transparent fabric. Riser is 4" for first step with 10" after that filled with R13.

I have read this thread until my eyes hurt and everything now is clear as mud. Can someone explain to me in simple english terms (I'm not an acoustic techy by any means) what I need to do to my room for acoustic treatments. The rooms is 20' wide, 37' long and 8' ceiling. I have downloaded the Sweetspot from Guide to Home Theater and it said I may have 11 frequency zone issues. I don't want to spend a gazillion dollars just want a good sounding home theater. First row seating at 9', second at 15' and bar at 21' with 7.1 system. Denon, Klipsch with 50" Pioneer 5010.

Can someone help? I have looked into computer programs too and I am no techy at this either. I'm a meat and potatoes guy. I don't want to hire a home theater tech to design all of this either. Hope this isn't offensive to anyone.
RG

Are your ICF (Insulated Concrete Form) walls covered with drywall? What are your goals? Are you looking for good sound only or are you looking for sound isolation along with good sound quality?

Are your ICF (Insulated Concrete Form) walls covered with drywall? What are your goals? Are you looking for good sound only or are you looking for sound isolation along with good sound quality?

Yep...need to know more about your goals. That's a pretty big space, so low end modal issues won't be as much of a problem, but intelligibility may be. I mean, you're always safe with the general answer: bass trapping in the corners and the back wall plus treatment at the reflection points for your seating area, but with HT things get a little more complicated once you start adding sconces, movie posters, aesthetic concerns, etc.

Frank

No rock on the ICF yet at this point. I thought about just putting the sound treatments directly over the ICF and then covering those with fabric.

Goal: sound isolation isn't a huge concern - want a good sounding home theater. Not afraid to do some DIY stuff.