Here is another place thast sells bags for corner traps if you want to make some on your own and save a few bucks:

http://www.readyacoustics.com/index.php?go=products.proddetails&prod=RT426B

Another quality resource:

http://sensiblesoundsolutions.com/

In fact, they had slightly better prices on several things I was shopping for.

Hi all

my new room will be 20' x 12' I plan to cover the screen wall in 4" auralex wedges and Lenrds corner base traps. The side wall will have 1" rockwool from about 1' up to 4' up covered with acoustically transparent cloth.



If it's not already a done deal, I'd recommend buying fiberglass panels/traps instead of the foam ones. In less space, and about the same price, you'll get far more effective treatments.

It is an already done deal. it is stuff I had in my old house and old room which I am re-using. I may double stack it so the wedges merge together to give me a more effective treatment as i have more than what I need. this stuff was very expensive at the time and I am loath to throw it away.

I also plan to build some soffits and fill with rockwool. My other base trap will now be my riser which I am going to cut some holes in the front and rear into the chambers which will also be filled with rockwool. Hopefully that should cover all the frequencies.

I have some left over Auralex DST-R's which are polystyrene diffusers. After some more research today I will place these on the rear wall behind the cloth as it cannot do any harm can it?

Now just the ceiling reflections to sort out :)

Right. the only thing is that with my wall being floating (I used RISC clips and/ green glue) I want to minimize the number of fastener holes I have to use to attach stuff to the walls, so I'm going to basically attach some "posts" at the proper weight bearing areas, and then build the frame and attach it to that. Then I think I'm going to attach the gom to that frame, and loosely attach the 703 behind it.

The 703 I'm putting up is 4'x8', 2" thick sheets, and I'm going to double layer them for a total of 4" of 703 material. That should be enough to kill the front wall reflections.

This is just for my front wall, which is going to have an AT screen hung in front of the material.
Same setup in my theater, but with 2" J-M Linacoustic on the front wall. I rely on SSC bass traps for absorption at the lower frequencies. 4" will absorb lower than 2", but it will not reach effectively to the bottom two octaves and you would need traps anyway.

Just my $.02.

See my link.

It is an already done deal. it is stuff I had in my old house and old room which I am re-using. I may double stack it so the wedges merge together to give me a more effective treatment as i have more than what I need. this stuff was very expensive at the time and I am loath to throw it away.

I know the feeling. I was able to sell about 3/4 of my Auralex foam on craiglist locally, and took a bit of a hit, but dumped the proceeds into fiberglass and never looked back.

But the stuff I couldn't sell, I re-used, for sure.

I also plan to build some soffits and fill with rockwool. My other base trap will now be my riser which I am going to cut some holes in the front and rear into the chambers which will also be filled with rockwool. Hopefully that should cover all the frequencies.

You'll want to read up on what size and variety of holes to drill/cut into the riser. The hoel size impacts which specific frequencies are trapped -- and unless you know you have a problem in one range of frequencies and can readily focus on those, broadband bass trapping is usually preferable.

I have some left over Auralex DST-R's which are polystyrene diffusers. After some more research today I will place these on the rear wall behind the cloth as it cannot do any harm can it?

My view is that diffusion is almost assuredly better than a plain wall, yes.

Another quality resource:

http://sensiblesoundsolutions.com/

In fact, they had slightly better prices on several things I was shopping for.

Great place to purchase BAC (Bonded Acoustical Cotton), which also comes in 5 1/2" bulk sheets if you want a non-fiberglass route. Bryan is a great guy to deal with there, and yes, great prices too.

Ray

You'll want to read up on what size and variety of holes to drill/cut into the riser. The hoel size impacts which specific frequencies are trapped -- and unless you know you have a problem in one range of frequencies and can readily focus on those, broadband bass trapping is usually preferable.




Thanks Nathan :)

Broadband trapping does sound to be the best option.

Are there any formulas for working it out. My riser will be in 2 sections screwed together. The rear section is 8' x 4' The front section will be 8' x 2' with a step at each side. It was easier to build that way but is essentially 2 separate pieces hence the comment about cutting the holes in the front and the rear. The inernals are partitioned into 2' wide sections.

maybe I can just cut different sized holes in each section :)

Lemme just throw this out there - the fiberglass materials we use for treatments are mostly all from the commercial contractor HVAC and insulation world. If one has the knowledge on what to buy and who to call, one can save a boatload of money. If the word "sound" or "acoustical" appears in the company's name, the boat becomes a dinghy.

Just my $.02.

Same setup in my theater, but with 2" J-M Linacoustic on the front wall. I rely on SSC bass traps for absorption at the lower frequencies. 4" will absorb lower than 2", but it will not reach effectively to the bottom two octaves and you would need traps anyway.
Just my $.02.
See my link.
Ya, I know I really should do bass traps as the 4" won't go quite low enough, but I am literally out of room to place them, with the exception of possibly the two rear corners of the room. With the door on the front wall, and the screen covering a good portion of it, I really don't have much to work with regarding bass traps. At least not enough depth to be able to do anything.....

I'm open to suggestions, but I knew this going into my build - that bass traps were going to be near impossible to place in the front of my room...

Ya, I know I really should do bass traps as the 4" won't go quite low enough, but I am literally out of room to place them, with the exception of possibly the two rear corners of the room. With the door on the front wall, and the screen covering a good portion of it, I really don't have much to work with regarding bass traps. At least not enough depth to be able to do anything.....

I'm open to suggestions, but I knew this going into my build - that bass traps were going to be near impossible to place in the front of my room...

Most do not have the space or funds available to go into a fully blown treated room. My advise would be to get your room the best that you can.

Are there any calculations available to show just how deep/shape/size of bass traps I would need to build in order to properly trap them?

Ya, I know I really should do bass traps as the 4" won't go quite low enough, but I am literally out of room to place them, with the exception of possibly the two rear corners of the room. With the door on the front wall, and the screen covering a good portion of it, I really don't have much to work with regarding bass traps. At least not enough depth to be able to do anything.....

I'm open to suggestions, but I knew this going into my build - that bass traps were going to be near impossible to place in the front of my room...
Look up. There are corners formed by the walls and the ceiling. :)

Are there any calculations available to show just how deep/shape/size of bass traps I would need to build in order to properly trap them?
Mouse around here (http://forum.studiotips.com/viewforum.php?f=8&sid=5237acaa70dc75ea49446fd9f67c861c).

Look up. There are corners formed by the walls and the ceiling. :)
I know. I don't even that THAT much space... It is TIGHT... example:

My door is a 6' 8" door, there's only 4" of clearance between the top of the door and the ceiling. My door is shoe-horned into the front right of the room, and there's only 3" between the door and the side wall.

Hi everyone,

I am planning to add a corner base traps, and due to a limited budget I am opting
a diagonal 4" OC703 (2" back to back together) from floor to ceilling it will be a DIY project and now my question is really about placement of my main speakers should I set my main speakers diagonal also behind the diagonal panel of it is ok facing straight towards the seating area. Thanks in advance, after treating my first reflection points the sounds improved so much that I am now ready to add corner traps.

Peter

Hi everyone,

I am planning to add a corner base traps, and due to a limited budget I am opting
a diagonal 4" OC703 (2" back to back together) from floor to ceilling it will be a DIY project and now my question is really about placement of my main speakers should I set my main speakers diagonal also behind the diagonal panel of it is ok facing straight towards the seating area. Thanks in advance, after treating my first reflection points the sounds improved so much that I am now ready to add corner traps.

Peter
I think your speakers should be positioned based on where the listeners are. Or maybe I'm not understanding your question?

I think your speakers should be positioned based on where the listeners are. Or maybe I'm not understanding your question?

Well what I mean is, should my main L/R speakers slightly angled facing the listeners or is it okey if my main speakers facing straight to the back wall (not angled.)

I am planning to add corner bass traps in the screen wall.

Well what I mean is, should my main L/R speakers slightly angled facing the listeners or is it okey if my main speakers facing straight to the back wall (not angled.)
Yep, OK, I always aim my speakers at the geographical center of the listening area. Off-axis tweeter response is usually irregular and aiming is a way to spread the highs as evenly as possible.

Yep, OK, I always aim my speakers at the geographical center of the listening area. Off-axis tweeter response is usually irregular and aiming is a way to spread the highs as evenly as possible.

Thanks Pepar, I will angled it towards the center of the listnening area thank you very much.

Thanks Pepar, I will angled it towards the center of the listnening area thank you very much.

You might want to consult your speaker manual or the dealer/company about this question to be sure.

For example, I have Dali speakers with ribbon tweeters and they are not supposed to be angled at all (which was weird to me at first, considering my previous soft-dome tweeters); however, they sound glorious in their non-angled position!

Just check to be sure...

You might want to consult your speaker manual or the dealer/company about this question to be sure.

For example, I have Dali speakers with ribbon tweeters and they are not supposed to be angled at all (which was weird to me at first, considering my previous soft-dome tweeters); however, they sound glorious in their non-angled position!

Just check to be sure...

ok thanks I check it to make sure

Hello, I'm sure this may have been asked before. While shopping at HD i found temple-inland soundchoice sound-deadening fiberboard for about $10 4'X8' 1/2" SHEET. I have looked at serval sites to see its acoustical absorbtion but have not found it. If anyone knows what it is or if it would be good for low frqs absorbtion please let me know.

Hello, I'm sure this may have been asked before. While shopping at HD i found temple-inland soundchoice sound-deadening fiberboard for about $10 4'X8' 1/2" SHEET. I have looked at serval sites to see its acoustical absorbtion but have not found it. If anyone knows what it is or if it would be good for low frqs absorbtion please let me know.

A good rule of thumb is to ignore any acoustical claims for construction materials which have "sound" anywhere in the product name. :(

A good rule of thumb is to ignore any acoustical claims for construction materials which have "sound" anywhere in the product name. :(

Thanks Terry,,
When ever possible I like to look at data. "Rule of thumb" is a good norm, however norms are followed as much as broken.
I was hoping someone had some tested values of the substance.


Thanks again for input,

If the company cannot produce the results of independent certified testing results documenting the product's acoustical properties, then do not use the product. This is a sound reproduction space. Products designed for, and typically used in, noise reduction applications for human speech (offices, conference rooms, homes) are not appropriate for this application.

Hi all,

My first post in this thread, but I have been a silent follower for a while now.

I am planning a dedicated media room and as I can't get OC703 in Sweden I have been looking at alternatives. I found some Isover Technical Insulation (http://www.isover.se/sw21736.asp) products which are not listed on bobgolds list, however I found the following data on their local web site (all measurements according to ISO 354)

Which, if any, of these would you recommend for use as absorption in corners / on walls? Watch the colour coding for the various thicknesses is not consistent.

138679

138676

138677

138678


Densities are between 35Kg (glass fiber) and 100Kg (mineral) per cubic meter. There is a perforated aluminum foil backing material on one side of the Cleantec Plus 6329 sheet.

It seemed to me that the Cleantec 8739 and the VVS sheet were most similar to OC703 at 2" (50mm).

hey everyone been a long time follower of avsforum, however this is my first post im doing my own acoustical treatment in my theatre room and am still kind of confused, i found a website readyacoustics.com sent him my google sketchup (my room is 13x15 with a stage and 2nd row riser as well as soffit above stage and along back wall to house projector) and he recommeneded "If there is no acoustic treatment present, and since you are still at the "build" stage, I'd recommend adding 4" thick absorption in some key locations:


Rear Wall
Side walls
Over your seating
Front left and right corners, and behind the screen


Focusing on these areas should result is better low frequency response and tighter, more predictable sound overall.
Finding the first reflection point is as easy as sitting in your listening position and having someone slide a mirror around on your side walls until you can see the speaker (or surrogate) in that mirror.
Where you see that speaker is the point at which you apply your broadband absorber(s).
Then, installation overhead as well as immediate left and right side walls, rear wall and vertical corners. If you can get 2, 48x24x4 inch bass traps in each corner, (vertically stacked), then your making the most of that installation location. If not, straddle a single broadband absorber across that corner, and try to touch the ceiling (or floor) plus your left and right side walls at the same time. In this manner, the absorber is touching 2-3 resonant surfaces and is helping to tame all of them at once.

does this sound accurate? and also i talked to a guy at home depot about gettin owens corning 705 and he told me to get roxul safe and sound instead anyone know if that will do the trick? any info is greatly appreciated, thanks guys!

Sure, that sounds accurate. You can always call them on the phone and get some clarification too.

Safe'n Sound will work fine in most places...705 is a good bit denser.

Frank

jay131011 - http://www.bobgolds.com/AbsorptionCoefficients.htm

jay131011 - http://www.bobgolds.com/AbsorptionCoefficients.htm

Wow! Awesome link, thanks Pepar!

Ray

wow thanks for the link it cleared alot up, I still have some questions though as im still pretty new to this, Ive about half of this thread and early on they say dont use 2" bc it might absorb to much, wouldnt 3" be even more absorbant? good or bad? and as first reflection points do i cover up to ear heigh or whole height of wall? also whats with everyone saying do ear height along side and rear walls, wouldnt you hit the first reflection points by doing that? I also plan to put diy base traps in the corners and some form of treatment on the tri corners where the walls meet the soffits does this sound correct? as you can tell im pretty confused haha. any info would be greatly appreciated!

wow thanks for the link it cleared alot up, I still have some questions though as im still pretty new to this, Ive about half of this thread and early on they say dont use 2" bc it might absorb to much, wouldnt 3" be even more absorbant?
What's "bc?"
And I've always wondered what "absorb too much" meant! :D

Regards,
Terry

wow thanks for the link it cleared alot up, I still have some questions though as im still pretty new to this, Ive about half of this thread and early on they say dont use 2" bc it might absorb to much, wouldnt 3" be even more absorbant? good or bad?

No...it doesn't work that way. Assuming it's the same density, it'll just extend the low end coverage of the panel. It'll absorb more down lower not more at the same frequencies.

and as first reflection points do i cover up to ear heigh or whole height of wall? also whats with everyone saying do ear height along side and rear walls, wouldnt you hit the first reflection points by doing that?

Ear height is fine in most cases. You're looking to control reflection along the plane of the seated listener's ear.

I also plan to put diy base traps in the corners and some form of treatment on the tri corners where the walls meet the soffits does this sound correct? as you can tell im pretty confused haha. any info would be greatly appreciated!

That sounds just fine.

Frank

What's "bc?"

It's the time period before the common era, but that's neither here nor there...;)

Frank

It's the time period before the common era, but that's neither here nor there...;)

Thank you, Weasel #9992!:D

i talked to a guy at home depot about gettin owens corning 705 and he told me to get roxul safe and sound instead

There are two issues - absorption and ease of use. One of the overwhelming advantages of 705 rigid fiberglass is that it's very rigid, and holds its shape well without sagging. It's also very easy to cut and make clean straight corners etc.

--Ethan

wow thanks for all the fast responses guys! youre all helping come along a lot faster, haha bc is short for because im 21 n text alot so i use short form.. thanks for the info again

There are two issues - absorption and ease of use. One of the overwhelming advantages of 705 rigid fiberglass is that it's very rigid, and holds its shape well without sagging. It's also very easy to cut and make clean straight corners etc.

Yep...the Safe'nSound will be less expensive though. Not that that matters necessarily.

Frank

Which, if any, of these would you recommend for use as absorption in corners / on walls? Watch the colour coding for the various thicknesses is not consistent.

138679
138676
138677
138678

Densities are between 35Kg (glass fiber) and 100Kg (mineral) per cubic meter. There is a perforated aluminum foil backing material on one side of the Cleantec Plus 6329 sheet.


I'd appreciate any advice on use of either of the above materials instead of OC703. Thanks!

I am trying to put acoustic treatments in my HT room and I have a general question. Is there any difference between the different companies panels? I have looked at Real traps, and I really like how extensive their offerings are as well as their customer service...I called with a question. But I have found cheaper alternatives, and I am wondering if certain companies use different materials? Or all they are just fiberglass? Thanks

I am trying to put acoustic treatments in my HT room and I have a general question. Is there any difference between the different companies panels? I have looked at Real traps, and I really like how extensive their offerings are as well as their customer service...I called with a question. But I have found cheaper alternatives, and I am wondering if certain companies use different materials? Or all they are just fiberglass? Thanks
My observation is that they all pretty much use the same materials. The differences will be in the product offerings, customer service/tech assistance and, of course, price. You need to find the balance that is most comfortable for you. Some go completely DIY, some hire a consultant for a turn-key solution and everyone else falls somewhere in between.

My observation is that they all pretty much use the same materials. The differences will be in the product offerings, customer service/tech assistance and, of course, price. You need to find the balance that is most comfortable for you. Some go completely DIY, some hire a consultant for a turn-key solution and everyone else falls somewhere in between.

Pepar pretty much nailed it on all counts. From a performance standpoint everbody's pretty similar, so it comes down to a number of other factors. There's also the option of DIY or a combination of the two.

Frank

Pepar pretty much nailed it on all counts. From a performance standpoint everbody's pretty similar, so it comes down to a number of other factors. There's also the option of DIY or a combination of the two.

Frank

Thanks. That was my suspicion.

I have a few questions, not sure if they have been answered before.

I'm moving and my new media room is a 10x10x8 sheet rock walled room. It has horrible flutter echo.

I have 2 questions. I don't have much to spend on acoustical treatment so is treating the first reflection point of each speaker enough to remove the flutter echo or do I need to do a completely 30-50% coverage on every wall?

I'm looking at getting the Auralex wedgies that are $5 for 1 foot squares. These look rather ugly by themselves so I was also wondering if anyone had any good ideas as far as how to make these look attractive in this small room? How to place them in a pattern or Can you paint them without removing their absorbing properties?

How many of these wedgies showed I be budgeting for?

Also there is a closet on the back wall. In that closet I have a couple shelves and I heard this can act as a poor man's diffuser and that the increased opening of the closet could help remove some reflections as is. Is this true, or am I mistaken? Would it be beneficial to just go ahead and remove those two doors? Also How should I position the wedges on the front and back wall?

Thanks for listening to these basic questions.

I have a few questions, not sure if they have been answered before.

I'm moving and my new media room is a 10x10x8 sheet rock walled room. It has horrible flutter echo.

I have 2 questions. I don't have much to spend on acoustical treatment so is treating the first reflection point of each speaker enough to remove the flutter echo or do I need to do a completely 30-50% coverage on every wall?

I'm looking at getting the Auralex wedgies that are $5 for 1 foot squares. These look rather ugly by themselves so I was also wondering if anyone had any good ideas as far as how to make these look attractive in this small room? How to place them in a pattern or Can you paint them without removing their absorbing properties?

How many of these wedgies showed I be budgeting for?

Also there is a closet on the back wall. In that closet I have a couple shelves and I heard this can act as a poor man's diffuser and that the increased opening of the closet could help remove some reflections as is. Is this true, or am I mistaken? Would it be beneficial to just go ahead and remove those two doors? Also How should I position the wedges on the front and back wall?

Thanks for listening to these basic questions.

Personally having avoided wedgies all my life, I have no idea how many you need. :D My media room is of similar size...10x12x8 with a closet in the rear and a door at 45 degrees. I did super chunk bass traps in all four corners (front left and right, and inside closet left and right). I also have two 2x4 cloud absorbers, one 2x4 panel on each side wall, one 2x4 panel angled at 45 degrees along the side walls/ceiling intersection. Finally, I have four 1x4 panels behind my tv/speakers. There's a large window right behind my TV, so I couldn't fully cover that wall.

After all of these treatments, acoustics are awesome. Whenever I have someone over, they comment even with no audio how different/silent the room feels. Before the treatments the slap echo was pretty bad.

I purchased a bunch of OC703 and covered with the black and tan GOM. Wasn't exactly cheap, but works great. I'd like to do more treatment, but I'm not sure how much more I can improve things. I haven't shelled out the $$ to get some professional readings to see what could use more work.

I have a few questions, not sure if they have been answered before.

I'm moving and my new media room is a 10x10x8 sheet rock walled room. It has horrible flutter echo.

I have 2 questions. I don't have much to spend on acoustical treatment so is treating the first reflection point of each speaker enough to remove the flutter echo or do I need to do a completely 30-50% coverage on every wall?

I'm looking at getting the Auralex wedgies that are $5 for 1 foot squares. These look rather ugly by themselves so I was also wondering if anyone had any good ideas as far as how to make these look attractive in this small room? How to place them in a pattern or Can you paint them without removing their absorbing properties?

How many of these wedgies showed I be budgeting for?

Also there is a closet on the back wall. In that closet I have a couple shelves and I heard this can act as a poor man's diffuser and that the increased opening of the closet could help remove some reflections as is. Is this true, or am I mistaken? Would it be beneficial to just go ahead and remove those two doors? Also How should I position the wedges on the front and back wall?

Thanks for listening to these basic questions.

Oh boy...10x10x8 is a rough set of dimensions. Flutter echo is going to be the least of your concerns. I know you said you don't have a big treatment budget, but you're really going to need to treat the crap out of this place. First, you've got a set of repeating dimensions, second the room is small...that adds up to big low end problems. I wouldn't put a panel under 4" thick in a room like this...you'll need thick bass trapping on the back walls, and straddling the corners floor to ceiling if possible.

Frank

Oh boy...10x10x8 is a rough set of dimensions. Flutter echo is going to be the least of your concerns. I know you said you don't have a big treatment budget, but you're really going to need to treat the crap out of this place. First, you've got a set of repeating dimensions, second the room is small...that adds up to big low end problems. I wouldn't put a panel under 4" thick in a room like this...you'll need thick bass trapping on the back walls, and straddling the corners floor to ceiling if possible.

I'm thinking "headphones" for this room. :D

hey guys quick question about treating the back wall and soffit housing the projector, the rears in my 5.1 setup are energy dipoles, how do i properly treat the back wall to take advantage of the sound stage they are supposed to create? thanks!

Alrighty,

First, I just want to thank you guys ahead of time (I am presuming upon your generosity) for your advice and help. Now to the gory details....

I have a thread going for my Home Theater construction (see link ink sig). My latest post addresses the issue of where to put bass traps. I have a large corner in the front left, but absolutely no corner on the right due to a door. However, I have built a false wall (part of the proscenium) that has corners containing the L/C/R speakers (but not the sub).

False Wall Corner (http://dl.getdropbox.com/u/332158/Home%20Theater/Bass%20Trap%20Help/DSCF1069.JPG)

Would it be beneficial to use these corners for bass traps? If I can't do any of the corners, what about just putting up a triangle/wedge trap made out of OC 703 behind the screen where the ceiling and soffit meet?

Ceiling & Soffit (http://dl.getdropbox.com/u/332158/Home%20Theater/Bass%20Trap%20Help/DSCF1065.JPG)

(I didn't know if pictures were allowed in this thread, so I just included the links)

Also, I am planning on using linacoustic all around the theater side walls (but only up to 3' due to design constraints). I will then have panels with OC 703 inside at the first reflection points. Of course, I am trying to do arched panels, so figuring out how to make a frame is going to be interesting....

Oh boy...10x10x8 is a rough set of dimensions. Flutter echo is going to be the least of your concerns. I know you said you don't have a big treatment budget, but you're really going to need to treat the crap out of this place. First, you've got a set of repeating dimensions, second the room is small...that adds up to big low end problems. I wouldn't put a panel under 4" thick in a room like this...you'll need thick bass trapping on the back walls, and straddling the corners floor to ceiling if possible.

Frank
Well the back left corner is actually a 1 foot wall at a 45 degree angel so it's not a PERFECT square :-P

I'm looking at getting acousticmac panels. They seem like aesthetically pleasing and fairly cheap treatment.

This room is primarily only going to be seating me myself and I so do I really need to worry about flattening out the bass response across the room if I can control it for the sweet spot?

Also, With bass trapping, is it an all or nothing deal or Can I get away with hitting one or two corners?

The front Left corner is where the door is so that'll make putting a bass trap difficult.

The back left corner is that 45 degree wall. Does it need a bass trap?

The front Right is where I'm thinking about putting a single bass trap because the sub is half way along the right wall pointed towards that corner (atleast for now).

The back right is a closet, But I'm leaning more and more to removing those two doors exposing the small closet behind.

I only have a modest system and I'd rather not spend more on treatment then my speakers.

Polk rti4s, csi3, velodyne vrp-1200, onkyo 506.

Any info is greatly appreciated.

Also, With bass trapping, is it an all or nothing deal or Can I get away with hitting one or two corners?

The front Left corner is where the door is so that'll make putting a bass trap difficult.

The back left corner is that 45 degree wall. Does it need a bass trap?

The front Right is where I'm thinking about putting a single bass trap because the sub is half way along the right wall pointed towards that corner (atleast for now).

The back right is a closet, But I'm leaning more and more to removing those two doors exposing the small closet behind.

I only have a modest system and I'd rather not spend more on treatment then my speakers.

It's best to treat symmetrically if you can, but if not, remember that there are more than four corners in a room. You can always hit the wall/ceiling corners as well. The front and back wall are still great candidates for bass trapping, as are the reflection points. Even in tough rooms there are almost always opportunities to absorb low end.

Frank

It's best to treat symmetrically if you can, but if not, remember that there are more than four corners in a room. You can always hit the wall/ceiling corners as well. The front and back wall are still great candidates for bass trapping, as are the reflection points. Even in tough rooms there are almost always opportunities to absorb low end.

Frank
By symmetrically do you mean front to back, or left and right?

hey guys im kinda stressed after my carpet was put in i sat down on my riser clapped my hands and there was a wierd "ttiiiiingg" noise i have all my acoustics up behind my screen wall but not on the side or rear walls yet, any idea what that could be and how i could possible get rid of it?

hey guys im kinda stressed after my carpet was put in i sat down on my riser clapped my hands and there was a wierd "ttiiiiingg" noise i have all my acoustics up behind my screen wall but not on the side or rear walls yet, any idea what that could be and how i could possible get rid of it?
That's your problem.

- Terry

By symmetrically do you mean front to back, or left and right?

Well, all around really. If you can't though, then you have to look at the room and decide where your treatment opportunities are and go from there.

Frank

hey guys im kinda stressed after my carpet was put in i sat down on my riser clapped my hands and there was a wierd "ttiiiiingg" noise i have all my acoustics up behind my screen wall but not on the side or rear walls yet, any idea what that could be and how i could possible get rid of it?

Yep...Terry already said it, but you've identified your own problem!

Frank

haha thanks guys i feel better now!

Are there any general principals for treating wall-mounted bipole surround speakers? Type of treatment? Location? Etc.? Thanks.

I am going to start painting my room this weekend. And after paint I am looking to start putting up treatments. But need an opinion regarding bass traps. I was planning to make super chunk style traps from OC703 for the front and rear corners and front wall/ceiling corner also. I was recently doing more research and read that it could be more beneficial to build traps, similar to the Real Traps Mondo traps, that are 2’x4’x4”, and using the extra material I would have left over to treat other corners of the room. Basically adding more square foot of coverage. Although I know my diy traps will not perform as well as the Mondo’s, I am on a budget so I am trying to make the best with what I have for now.

For more info on the room, size is 11.5'x15'x8', and I will have all the first reflection points treated in addition to the bass traps.

I am going to start painting my room this weekend. And after paint I am looking to start putting up treatments. But need an opinion regarding bass traps. I was planning to make super chunk style traps from OC703 for the front and rear corners and front wall/ceiling corner also. I was recently doing more research and read that it could be more beneficial to build traps, similar to the Real Traps Mondo traps, that are 2’x4’x4”, and using the extra material I would have left over to treat other corners of the room. Basically adding more square foot of coverage. Although I know my diy traps will not perform as well as the Mondo’s, I am on a budget so I am trying to make the best with what I have for now.

For more info on the room, size is 11.5'x15'x8', and I will have all the first reflection points treated in addition to the bass traps.
Test data here (http://forum.studiotips.com/viewtopic.php?f=8&t=536) indicates that a filled triangle outperforms one not filled. But sometimes compromises need to be made. :)

Don't sell DIY short. In most cases, there is no difference.

Test data here (http://forum.studiotips.com/viewtopic.php?f=8&t=536) indicates that a filled triangle outperforms one not filled. But sometimes compromises need to be made. :)

Don't sell DIY short. In most cases, there is no difference.

+1 to all of that. If you can fill the corner then you should...and I've seen some fantastic DIY jobs. If you're careful and methodical it'll turn out great.

Frank

NEW QUESTION: In a small-ish dedicated theatre room (12'w x 18' D x 7' H), that has a fabric-covered false screenwall that is 30" from the actual wall using a 7' wide 2:35 non-perf screen, should the ENTIRE CAVITY be covered with something? In other words, you have the following areas of bare drywall unless treated....

- wall behind the screen
- sidewalls behind the screen
- ceiling behind the screen

I think most would agree that the wall behind the screen needs treatment, but what about the other two areas?

Again, keep in mind I'm not asking about first reflection sidewall or ceiling treatment as those will be outside of the screenwall and are taken care of. I am talking about whether or not in a false wall set-up you should cover all surfaces behind the screen or not, and why???

Thanks!

NEW QUESTION: In a small-ish dedicated theatre room (12'w x 18' D x 7' H), that has a fabric-covered false screenwall that is 30" from the actual wall using a 7' wide 2:35 non-perf screen, should the ENTIRE CAVITY be covered with something? In other words, you have the following areas of bare drywall unless treated....

- wall behind the screen
- sidewalls behind the screen
- ceiling behind the screen

I think most would agree that the wall behind the screen needs treatment, but what about the other two areas?

Again, keep in mind I'm not asking about first reflection sidewall or ceiling treatment as those will be outside of the screenwall and are taken care of. I am talking about whether or not in a false wall set-up you should cover all surfaces behind the screen or not, and why???

Thanks!
The advice when I built mine 4-5 years ago for a micro-perfed Stewart screen was to line the entire cavity with 2" of 'glass. The reason as I understood it was to reduce/eliminate comb filtering from the sound bouncing around behind the screen. I imagine that the same thinking would apply today?

The advice when I built mine 4-5 years ago for a micro-perfed Stewart screen was to line the entire cavity with 2" of 'glass. The reason as I understood it was to reduce/eliminate comb filtering from the sound bouncing around behind the screen. I imagine that the same thinking would apply today?

That is what I would think, and how I often see them built. I was told that I only needed to worry about reflections that occurred around my ears and that meant I didn't need to worry about the sliver of sidewall and ceiling behind the screenwall that were untreated. Of course, unless you do something you can't be sure if it is going to be better.

Thanks for the advice.

Anyone else with experience in this area?

That is what I would think, and how I often see them built. I was told that I only needed to worry about reflections that occurred around my ears and that meant I didn't need to worry about the sliver of sidewall and ceiling behind the screenwall that were untreated. Of course, unless you do something you can't be sure if it is going to be better.
My concern is that any sound coming out of that area that is not direct can only blur the direct sound.

The advice when I built mine 4-5 years ago for a micro-perfed Stewart screen was to line the entire cavity with 2" of 'glass. The reason as I understood it was to reduce/eliminate comb filtering from the sound bouncing around behind the screen. I imagine that the same thinking would apply today?
When I did mine just a few months ago, Terry Montlick gave me the same advise. I had only one inch up and the second layer of 1" linacoustic made a big difference. I asked about going with 3 inches since I have plenty of extra but never got a reply. I took that to mean that two was enough.

My scr5een is not micro-perfed.

OK, I have an odd question here.

My fiancé and I are bouncing design (as in aesthetic design) ideas off each other on how we want to put some sound absorption on the ceiling at first reflection points. Patterns, shapes, wood frame exposed or hidden, all that sort of thing.

So I have this great idea that I believe will work both aesthetically as well as sonically, but it involves one of two options because 5 sides of the ridged insulation will be visible:

#1, either I buy a ton of cloth and completely wrap each piece before mounting (super expensive! and very labor intensive)

#2, a light spray of paint to turn the yellow insulation a reasonable shade of black on all sides.

Now, I know having the insulation exposed isn't a good thing, but it's going to be on the ceiling, it's not going to be moved or rustled, and I feel the spray paint will help contain the fibers.

Which brings me back to the original question...would spraying on a couple thin layers of a quality spray paint destroy the insulations acoustic properties? I've been day-dreaming about it for a couple hours, and I honestly think not.

Thoughts?

When I did mine just a few months ago, Terry Montlick gave me the same advise. I had only one inch up and the second layer of 1" linacoustic made a big difference. I asked about going with 3 inches since I have plenty of extra but never got a reply. I took that to mean that two was enough.

My scr5een is not micro-perfed.
I've seen some recommend thicker to "reach" lower, but bass traps are needed anyway and in my room it's all worked out nicely.

Thoughts?
Frames (http://www.peparsplace.com/Pg_16.htm)? Otherwise, how were you planning on fastening then in place?

I've seen some recommend thicker to "reach" lower, but bass traps are needed anyway and in my room it's all worked out nicely.
Right. In my case, I can actually get 4" on my front wall, but I don't have the room to put bass traps in the front of the room (I know I've mentioned this before, but alas). So I'm going to put 4" of 703 on my entire front wall, except the door. I'm going to hang 2" on my door with a 1" gap behind it, because that's all I can fit in that corner.

Then I'll do the normal early reflection points, a good portion of the back wall, and the rear wall-to-wall corners as bass traps. I don't have enough head room to do the wall-to-ceiling corners...

Hopefully, it'll be a significant improvement over what I Have now.


Actually, that leads to my next question. I bought a lap top - an HP pavillion running Vista home x64. I want to take measurements in my room so I have a better idea of what I'm working with and how my treatments will change the room.

I'm thinking that I can use this: http://www.hometheatershack.com/roomeq/

But, what should I get for a microphone? Any suggestions?

But, what should I get for a microphone? Any suggestions?
Behringer ECM8000 Measurement Microphone.
At $50, it is a winner in price vs. performance. You will need a phantom power preamp to go with it, but this is true of most microphones these days.

- Terry

Behringer ECM8000 Measurement Microphone.
At $50, it is a winner in price vs. performance. You will need a phantom power preamp to go with it, but this is true of most microphones these days.

- Terry
Phantom power preamp? I'm assuming I can just google these and find what I need.

A couple more questions regarding corner bass traps:

Is it better to completely fill the corner with material (in this case, OC703) or to leave a gap between the corner and the material?

Is there any rule of thumb to determine how deep the traps should be and/or how wide they should be? At the moment, I was thinking of simply cutting the OC703 sheets into 24" squares, then cutting them in half forming a triangle, then placing that triangle into the corner. That would make for a 24" wide face, and a trap that is roughly 17" deep. Is this going to be satisfactory? Is there a way to calculate what is really needed?

Thanks in advance.

A couple more questions regarding corner bass traps:

Is it better to completely fill the corner with material (in this case, OC703) or to leave a gap between the corner and the material?

Is there any rule of thumb to determine how deep the traps should be and/or how wide they should be? At the moment, I was thinking of simply cutting the OC703 sheets into 24" squares, then cutting them in half forming a triangle, then placing that triangle into the corner. That would make for a 24" wide face, and a trap that is roughly 17" deep. Is this going to be satisfactory? Is there a way to calculate what is really needed?

Thanks in advance.

The only thing I can think of that would be better than that barring any specialty setup would be to use OC705.

Not a pure acoustics question, but related:

The areas immediatly to the sides of my screen will be flanked with floor to ceiling drapes. The drywall directly behind these drapes will be covered with JM Linacoustic.

Does anyone feel it necessary to cover the linacoustic with GOM before hanging the drapes. The wall behind the drapes will never be seen, nor disturbed.

Just wondering if covering the Linacoustic is recommended to keep the insulation "dust or fibers" contained, or perhaps this is necessary for code concerns?

Thanks in Advance!

Alrighty,

NEW QUESTION:

I have a thread going for my Home Theater construction (see link ink sig). My latest post addresses the issue of where to put bass traps. I have a large corner in the front left, but absolutely no corner on the right due to a door. However, I have built a false wall (part of the proscenium) that has corners containing the L/C/R speakers (but not the sub).

False Wall Corner (http://dl.getdropbox.com/u/332158/Home%20Theater/Bass%20Trap%20Help/DSCF1069.JPG)

Would it be beneficial to use these corners for bass traps? If I can't do any of the corners, what about just putting up a triangle/wedge trap made out of OC 703 behind the screen where the ceiling and soffit meet?

Ceiling & Soffit (http://dl.getdropbox.com/u/332158/Home%20Theater/Bass%20Trap%20Help/DSCF1065.JPG)

(I didn't know if pictures were allowed in this thread, so I just included the links)

Also, I am planning on using linacoustic on the entire front wall and all around the theater side walls (but only up to 3' due to design constraints). I will then have panels with OC 703 inside at the first reflection points. Of course, I am trying to do arched panels, so figuring out how to make a frame is going to be interesting....

BUMP.........seems I got lost in the madness!

BUMP.........seems I got lost in the madness!
:eek: It can't hurt.

Are there any general principals for treating wall-mounted bipole surround speakers? Type of treatment? Location? Etc.? Thanks.

Anyone?

Anyone?
I would not place any acoustical treatments near a dipole or bipole surround speaker.

I would not place any acoustical treatments near a dipole or bipole surround speaker.

What's considered 'near' ? I have both.

Well, actually, that's a decent question:

How do you determine whether or not to use dipole or bipole on the sides and/or rear? Or maybe that question is outside the scope of this thread.

What's considered 'near' ?


Yeah, I would like to know this as well. There is a corner bass trap thats about 2 or 3 feet from one of my surrounds. Of course, maybe it's irrelevant sine I can't move either of them.

Dipole/Bipoles can benefit from diffusion from the speaker to about 2'.

Dipole/Bipoles can benefit from diffusion from the speaker to about 2'.
Yes, I thought about adding the word "absorption" to my post, but neglected to do so. :o

Bump;

Anyone have an opinion on NOT covering linacoustic...?

I am about to add more SSC bass traps to my room that are not behind the false wall and need to be covered. I have black GOM, but would like to cover them with a color that matches my walls. Are there any commercialy available fabrics that should NOT be used to cover this style bass traps?

I would not place any acoustical treatments near a dipole or bipole surround speaker.

Actually, these can benefit quite a bit from adding diffusion to areas in the line of sight of where the drivers are directed. That way, you're taking an already effective design in terms of using the room to good advantage even better by taking what otherwise would be a series of direct reflections and spreading those out even more evenly. Diffusion where the sound of the driver would otherwise hit a bare wall. A good question!

Actually, these can benefit quite a bit from adding diffusion to areas in the line of sight of where the drivers are directed. That way, you're taking an already effective design in terms of using the room to good advantage even better by taking what otherwise would be a series of direct reflections and spreading those out even more evenly. Diffusion where the sound of the driver would otherwise hit a bare wall. A good question!
I think the context was "around" these speakers.

To your point, though, I have a totally dead front end and have considered placing skylines so that the front lobe of the side surround dipoles doesn't die immediately like it does now.

Dipole/Bipoles can benefit from diffusion from the speaker to about 2'.

+2. We commonly recommend that for dipoles...depends on the rest of the room context though.

Frank

Not a pure acoustics question, but related:

The areas immediatly to the sides of my screen will be flanked with floor to ceiling drapes. The drywall directly behind these drapes will be covered with JM Linacoustic.

Does anyone feel it necessary to cover the linacoustic with GOM before hanging the drapes. The wall behind the drapes will never be seen, nor disturbed.

Just wondering if covering the Linacoustic is recommended to keep the insulation "dust or fibers" contained, or perhaps this is necessary for code concerns?

Thanks in Advance!

Does anyone feel strongly either way;

1) covering linacoustic in GOM
or
2) is covering with a curtain not advised

Thanks!

Covering linacoustic ...

Here is the generic answer to all fiberglass based board products:

Certain manufactured board products (including duct liner and Coated Insul-Shield Black) have been approved for installation in free air spaces. In other words, when installed according to the manufacturer's instructions, these fiberglass products will not "shed" fibers into the air and are allowed to be installed in rooms without additional protective coverings.

If the product is not so certified (review the MSDS for the product), then that product must be covered with another barrier (such as GOM).

Thanks Dennis - appreciate it !!

Gonna start my first GIK panel trial and error. I have a 11 wide by 17 long 7 foot high ceiling room. The speakers , sub, and 60 inch tv are on the 11wide wall space. Im sitting about 10 feet back from the front. Im using 100 percent HT klipsch speakers. What do you think I should use. Absorb as much as the wall behind the speakers as possible? Diffusors or absorbers along the side walls? I have bipoles and Ive been told not to put absorbers close to them. Since im 7 feet from the back wall do I need to put any treatments back there? It seems like a pretty basic setup and I read as much literature as I can but it seems to get blurred on opinion/fact. Thanks.

Gonna start my first GIK panel trial and error. I have a 11 wide by 17 long 7 foot high ceiling room. The speakers , sub, and 60 inch tv are on the 11wide wall space. Im sitting about 10 feet back from the front. Im using 100 percent HT klipsch speakers. What do you think I should use. Absorb as much as the wall behind the speakers as possible? Diffusors or absorbers along the side walls? I have bipoles and Ive been told not to put absorbers close to them. Since im 7 feet from the back wall do I need to put any treatments back there? It seems like a pretty basic setup and I read as much literature as I can but it seems to get blurred on opinion/fact. Thanks.

Bass trapping on the back wall...look into the possibility of diffusion for the front wall. The rear corners can be used for bass trapping as well...*possibly* the front corners depending on how far apart the speakers are.

Frank

Ok, I have the bass traps under control but have a question on the broadband (first reflection point) panels. I am going to use 2" OC703 spaced 2" from the wall. But I was actually going to build spacers that I will attach to the wall, and mount the OC703 to that, then cover that with poly batting. This way the panels are usable while I construct my frames and paint them, then I will mount them over the panels already secured to the wall. Only thing is poly batting seems to only come in white. And since I am making 18+ 2'x2' panels, it will probably take several months to actually complete all of them. Can I paint or dye the batting black? I would like to have the room usable while I am working on the cosmetic frames. And having all that white on the walls is not ideal.

Mark

Poly batting isn't really a finishing material. It doesn't look great exposed. Use acoustically transparent fabric instead.

- Terry

Hey Mark...I agree with Terry that it's not a good finishing material, but if you're just putting up temporarily while you finish the frames for the panels, then that's fine. It won't look great, but as long as you can live with it I don't see any harm.

Frank

put curtains up in the living room. What a difference!! (visually) :(

The wife came back with a much thinner fabric than I was expecting. Oh well, it's our hangout space, not our acoustic perfection space. :)
I'll get that area going when we buy a house.

What I meant was that I am building finish grames with black GOM in the center. This will cover the panels that I am attaching to the walls. I have seen several builds where people use batting between the OC703 and the GOM. I just did not want a bunch of white panels on the walls (for temporary) while I am making my finial frames with GOM inserts. I would not want to watch movies with all the unfinished panels on the walls if left white. Just wondered if painting the batting black would cause a problem with sound? Or is batting really needed? That would cut down on cost also if I eliminated the batting.

Mark

Or is batting really needed? That would cut down on cost also if I eliminated the batting.

It really isn't needed. Fabric right over the 703 is just fine.

Frank

Good People,

Excuse the nooby question, but is it better to treat the tri-corners (wall-wall-ceiling or wall-wall-floor) or the corners created by two walls with bass traps first?

I went through my room and measured the spl at the different corners in my room. I started with a reference of 75dB at my "sweet spot" and then started measuring with a Rat Shack meter the different corners. I found my wall-wall-ceiling readings to be consistent at about 80dB, my wall-wall corners to be 78-79dB, and my wall-wall-floor readings to be about 83dB. I have pictures available if that would help.

Thanks.

Good People,

Excuse the nooby question, but is it better to treat the tri-corners (wall-wall-ceiling or wall-wall-floor) or the corners created by two walls with bass traps first?

If you have an untreated room, it is better to get your room reverberation under control with wideband acoustic panels first. Then you can worry about bass traps.

There is more area to effectively treat if you deal with the four 2-corner wall intersections. Going floor to ceiling with a nice deep corner absorber can be very effective. Unfortunately, the sound level measurements you made in the corners don't yield any useful information. :(

Regards,
Terry

If you have an untreated room, it is better to get your room reverberation under control with wideband acoustic panels first. Then you can worry about bass traps.

There is more area to effectively treat if you deal with the four 2-corner wall intersections. Going floor to ceiling with a nice deep corner absorber can be very effective. Unfortunately, the sound level measurements you made in the corners don't yield any useful information. :(

Regards,
Terry

Thanks Terry.

I have a few diy panels that I have placed behind my mains, center, and on the back wall directly behind the listening position.

So could I assume from you comment, that it is better to treat surface area rather than where the spl peaks are? What else could I provide that would be more helpful? Pictures, layout, etc.?

What else could I provide that would be more helpful? Pictures, layout, etc.?

Both would be great!

Frank

Thanks Terry.

I have a few diy panels that I have placed behind my mains, center, and on the back wall directly behind the listening position.

So could I assume from you comment, that it is better to treat surface area rather than where the spl peaks are?
Yes. The spl peaks will be high in corners and at surfaces. That is where pressures must be high. But you can't really tell anything from the single numbers you read on a meter. Even pressure as a function of frequency is of little use in determining treatment spots.

What else could I provide that would be more helpful? Pictures, layout, etc.?
Yes. :)

Both would be great!

Frank

As requested by Terry and Frank:

http://img90.imageshack.us/img90/2522/layoutn.jpg (http://img90.imageshack.us/my.php?image=layoutn.jpg)

http://img90.imageshack.us/img90/9957/basstrapmeas01.jpg (http://img90.imageshack.us/my.php?image=basstrapmeas01.jpg)

http://img90.imageshack.us/img90/1363/basstrapmeas02.jpg (http://img90.imageshack.us/my.php?image=basstrapmeas02.jpg)

http://img162.imageshack.us/img162/5296/basstrapmeas03.jpg (http://img162.imageshack.us/my.php?image=basstrapmeas03.jpg)

With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways. :) Like the Energizer Bunny, it keeps on going! Especially low frequency sound. This means that subwoofer frequencies can easily escape into larger spaces, and may not be an issue. Higher frequencies, on the other hand, are more readily trapped between parallel walls, and may create problems.

- Terry

With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways. :) Like the Energizer Bunny, it keeps on going! Especially low frequency sound. This means that subwoofer frequencies can easily escape into larger spaces, and may not be an issue. Higher frequencies, on the other hand, are more readily trapped between parallel walls, and may create problems.

- Terry

So what are your recommendations? There are very few reflection points left. Ceiling, above the entertainment center, above the picture, etc.?

So what are your recommendations? There are very few reflection points left. Ceiling, above the entertainment center, above the picture, etc.?
Yes. I see lots of lovely open wall space (which your wife may not). Absorbers don't need to be restricted to first reflection points.

Is it better to use absorbers that are effective down below 80hz on the front wall or absorbers that are effective down to 250hz? GIK 242 vs GIK 244 for front wall deadening?

No one seems to visit this board anymore. I ordered gik tri traps and 3 242 panels for first reflection points and behind the center channel. The trip traps cover alot of the 3 feet of space I have from the side of the tv to the wall. Well see how it goes.

Is it better to use absorbers that are effective down below 80hz on the front wall or absorbers that are effective down to 250hz? GIK 242 vs GIK 244 for front wall deadening?

Either one would be fine, honestly...depends on the issues you're having. If it's a small room, then the 244 is probably the right choice because it's a broad band panel. Then again, you might not have the space in a smaller room for a 4" panel on the front wall and reflection points. It depends totally on the room.

Frank

I have a null at 70hz in the vertical plane and it just so happens to be at the same height my head is when sitting on my couch, what kinds of acoustical treatments would help me out?

I have a null at 70hz in the vertical plane and it just so happens to be at the same height my head is when sitting on my couch, what kinds of acoustical treatments would help me out?
34" face SSC Bass traps (http://forum.studiotips.com/viewtopic.php?f=8&t=535). Or something tuned to your null.

So you guys don't know what I can do with my situation? I posted twice, but apparently I smell or something....:(

I have a null at 70hz in the vertical plane and it just so happens to be at the same height my head is when sitting on my couch, what kinds of acoustical treatments would help me out?
Treatments for vertical modes this low in frequency are largely ineffective. Just raise your subwoofer on a large, heavy box so it is closer to ear level. Assuming it is such a vertical mode (you'd get one with an 8' ceiling), the null should disappear.

- Terry

Alrighty,

First, I just want to thank you guys ahead of time (I am presuming upon your generosity) for your advice and help. Now to the gory details....

I have a thread going for my Home Theater construction (see link ink sig). My latest post addresses the issue of where to put bass traps. I have a large corner in the front left, but absolutely no corner on the right due to a door. However, I have built a false wall (part of the proscenium) that has corners containing the L/C/R speakers (but not the sub).

False Wall Corner (http://dl.getdropbox.com/u/332158/Home%20Theater/Bass%20Trap%20Help/DSCF1069.JPG)

Would it be beneficial to use these corners for bass traps?

In general, yes.
If I can't do any of the corners, what about just putting up a triangle/wedge trap made out of OC 703 behind the screen where the ceiling and soffit meet?

Not nearly as good a solution. Room corners are superior.

- Terry

Treatments for vertical modes this low in frequency are largely ineffective.- Terry
Even a chunk-style trap installed at a wall/ceiling juncture?

Even a chunk-style trap installed at a wall/ceiling juncture?
You'd have to put these all the way around the perimeter of the room to have a significant effect.

In general, yes.

Not nearly as good a solution. Room corners are superior.

- Terry

Thank you for replying!

Would you recommend doing just one of the front room corners (which is where the subwoofer will be located) without being able to do the other? And then doing the false wall corners as well?

Thank you for replying!

Would you recommend doing just one of the front room corners (which is where the subwoofer will be located) without being able to do the other? And then doing the false wall corners as well?
Low frequency room mode treatment is equally effective in all corner(s). No advantage to having it in the same corner as the sub.

- Terry

You'd have to put these all the way around the perimeter of the room to have a significant effect.

Definitely the more square footage you cover, the better.

Frank

Im doing a makeover in my existing theater, room is approx 13 x 17 currently with mid/high frequency absorbers on the wall at first reflection points. I want to cover the wall with wallfabric which with the installation tracks that mount to the wall will put the fabric 1 inch off the wall so I figured I could get rid of my absorbers and just do like everyone seems to be doing that do fabric walls which is to put 1" lincoustic up to ear height around the room then cover with wallfabric in front of that. I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?. At this point I guess what I will do is still mount my walltraps on the wall but place the framing tracks for the GOM fabric around them so I can have the best of both worlds. The only thing I dont know is should I still place 1" lincoustic on the wall behind the wallfabric. If I dont get this right it could be a costly mistake. If anyone wants to see pics of my room there are some in my signature from the article that appeared in the electronic house magazine in print and online. Any suggestions would be helpful at this point.

I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?.

I'll second that engineer's recommendation. I see many doing it, and every room I've been in has faced similar issues. I'm still a fan of wider bandwidth devices (usually thicker) in select locations and leaving enough reflective area elsewhere to keep the room from sounding too dead or over damped above 1-2kHz.

Bear in mind that we, as humans live in a highly reflective world. So our hearing has adapted to a reflective environment. Because of this, in many cases a 'dead' room actually sounds less appealing to us because we are accustomed to hearing things in a live environment.

So the key is not to make the room totally dead, but to address the focal points of where you are hearing the sound source.

Better yet, get some free software and a calibrated mic and take some measurements. Alternatively, one can listen to different conflicting opinions and make a decision w/o any data on the space in question. :)

Yup. I still have to get a microphone. Trying to find a decent preamp for it.

Yup. I still have to get a microphone. Trying to find a decent preamp for it.

I'm a mix engineer by trade, and I'd tell you to just get an EMC8000 (Behringer) and an M-Audio DMP3. You'll spend about $150 on both, and they'll work great for measurement purposes.

Frank

I'm a mix engineer by trade, and I'd tell you to just get an EMC8000 (Behringer) and an M-Audio DMP3. You'll spend about $150 on both, and they'll work great for measurement purposes.

Frank

I can find the ECM8000 for pretty cheap ($50 +/-), but where can you find the M-Audio DMP3 for less than $150?

Thanks,
CJ

I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?

Nice theater. Cool slide show.

The simple answer to your question is: mostly. If you have covered the first reflection points, covering more of the walls at random (or "up to ear level all around") with high frequency absorption is likely to have a negative impact on the quality of the sound in the room.

In fact, looking at your room, I'd say you've got several first reflection points covered -- GOOD. Cover them all and you'll be half way there.

The other half? Bass trapping. Unless there is something hiding somewhere, it looks like you need bass trapping. Which means thick bulky stuff in the corners. Lots of good DIY examples around here, and many good commercial options, as well.

Measurements would be cool, and tell you even more, but there are few rooms that cannot benefit from more bass trapping, so that's a safe suggestion and probably your biggest bang-for-buck improvement option.

Nice theater. Cool slide show.

The simple answer to your question is: mostly. If you have covered the first reflection points, covering more of the walls at random (or "up to ear level all around") with high frequency absorption is likely to have a negative impact on the quality of the sound in the room.

In fact, looking at your room, I'd say you've got several first reflection points covered -- GOOD. Cover them all and you'll be half way there.

The other half? Bass trapping. Unless there is something hiding somewhere, it looks like you need bass trapping. Which means thick bulky stuff in the corners. Lots of good DIY examples around here, and many good commercial options, as well.

Measurements would be cool, and tell you even more, but there are few rooms that cannot benefit from more bass trapping, so that's a safe suggestion and probably your biggest bang-for-buck improvement option.

Thanks Nathan, it doesn't look quite so cool now since its in a state of renovation, well it seems like based on my calculations from various seats regarding my reflection points I will end up with a 48" trap on either side of the wall and will forgo any lincoustic material and add about 4" or more of trapping on the front wall below the screen and in back of the front speakers. Thanks for everyone who added a little something to the mix and also thanks to Mark Seaton who picked up the phone and gave me some good advice. I invested in him early on (catalysts,submersives..etc) and its paying off :D

I can find the ECM8000 for pretty cheap ($50 +/-), but where can you find the M-Audio DMP3 for less than $150?

Thanks,
CJ

I've seen it on Ebay and on the net for $99.99 from time to time.

Frank

There are five or six on ebay Buy It Now at $159, but with the Best Offer option. And there is a regular auction at $61 and four days to go. And one at $12 with five days to go.

Sweetwater has the M-Audio DMP3 for 159.99 with free shipping.

http://www.sweetwater.com/store/detail/DMP3

Here is another option: Tascam US-144 which is 149.99 with free shipping (I'm using this unit and it works very well).

http://www.sweetwater.com/store/detail/US144/

I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?

Mark Seaton gave you the right answer too. As I explained on the phone, there are three problems with what you propose:

1) Rigid fiberglass only one inch thick does not absorb to a low enough frequency. I suggest two inches thick as a minimum. Otherwise all you'll absorb is treble and a little midrange. If your fabric track is only one inch deep, attach it to firring strips to bring it our farther and make a deeper cavity to accommodate two-inch fiberglass (or two layers of one inch).

2) Absorbing the lower half of a wall up to ear level kinda misses the mark. It covers the very bottom of the wall where absorption is not needed, and leaves the part just above your ears reflective. Sound leaves loudspeakers in an arc, spreading upward, downward, and outward the farther it goes. So absorption should extend to at least a foot above ear level on the side walls.

3) Covering a 4-foot high swath around the room centered at ear level is fine, but covering all of the walls from floor to ceiling is definitely too much absorption. Even a band going all around the room is probably too much since what really matters are the reflection points.

--Ethan

Sweetwater has the M-Audio DMP3 for 159.99 with free shipping.

http://www.sweetwater.com/store/detail/DMP3

Here is another option: Tascam US-144 which is 149.99 with free shipping (I'm using this unit and it works very well).

http://www.sweetwater.com/store/detail/US144/
I would follow the two auctions and bid in the last five seconds if the price hasn't gotten bid too high before coughing up $160 . . .

I would follow the two auctions and bid in the last five seconds if the price hasn't gotten bid too high before coughing up $160 . . .

That would be my preference too. However, I have a while before I need one and I think that Will should have first dibs.

CJ

I would follow the two auctions and bid in the last five seconds if the price hasn't gotten bid too high before coughing up $160 . . .

Agreed! I'd do the same.

Mark Seaton gave you the right answer too. As I explained on the phone, there are three problems with what you propose:

1) Rigid fiberglass only one inch thick does not absorb to a low enough frequency. I suggest two inches thick as a minimum. Otherwise all you'll absorb is treble and a little midrange. If your fabric track is only one inch deep, attach it to firring strips to bring it our farther and make a deeper cavity to accommodate two-inch fiberglass (or two layers of one inch).

2) Absorbing the lower half of a wall up to ear level kinda misses the mark. It covers the very bottom of the wall where absorption is not needed, and leaves the part just above your ears reflective. Sound leaves loudspeakers in an arc, spreading upward, downward, and outward the farther it goes. So absorption should extend to at least a foot above ear level on the side walls.

3) Covering a 4-foot high swath around the room centered at ear level is fine, but covering all of the walls from floor to ceiling is definitely too much absorption. Even a band going all around the room is probably too much since what really matters are the reflection points.

--Ethan


Ethan thanks for the reply, heres my game plan as per speaking with you and Mark on the phone last night. I plan on mounting 1" furring strips(top and bottom) horizontally across the wall then add my 1" track around the perimiter of the wall to attach the wall fabric, the fabric is going over the furring strips. I then I will reattach my wall 2" panels to the furring strips on the wall which when attached will have a 1" gap between the wall and the back the panel. In looking at reflection points from ALL my seats is seems that I am in need of two panels measuring 4x4 which is to say 2 2x4 panels right next to each other,same on the other wall, and a panel right on the door which will be a reflection point next to my right speaker. Mark then suggested that with the room I have underneath the screen (about 22"_ high x 8" deep) between the back of the speakers and the front wall that I put 4" or possibly more of fiberglass or rockwool on that wall so thats what I plan on doing. As far as bass traps, all total there will be a total of 7 and thats squeezing in one more trap on the ceiling above the seating area where the ceiling meets a soffited area, currently there is one there and I will add another 4 inch panel. The room will be chock full of panels. Thanks for the help now its time to get to work.

To All,

Thanks for discussing this topic; "too-much-sidewall" treatments - you have all just helped me make a decision NOT to cover my entire sidewall areas with Linacoustic. For sidewalls I will treat only the sidewall reflection points.

I will now concentrate on the screen-wall and seeing if I can go beyond 3 corner traps.
My corner traps are all up front; 2 vertical corners, and one across the top (wall to ceiling interface). I now need to find a way to get more bass trapping into the rear of my room.

FWIW: Mark/Wayne >> met you both at Zamboniman's first meet, was traveling when the 2nd one occured. Hope all is well for you guys!!

To All,

Thanks for discussing this topic; "too-much-sidewall" treatments - you have all just helped me make a decision NOT to cover my entire sidewall areas with Linacoustic. For sidewalls I will treat only the sidewall reflection points.

I will now concentrate on the screen-wall and seeing if I can go beyond 3 corner traps.
My corner traps are all up front; 2 vertical corners, and one across the top (wall to ceiling interface). I now need to find a way to get more bass trapping into the rear of my room.
That is exactly where I am right now. My "three corner" front traps are behind my false wall, so I did not have to be concerned that much with appearance. The ones I add in the rear of the room will be visible and will need to be covered to avoid being a sore thumb.

That is exactly where I am right now. My "three corner" front traps are behind my false wall, so I did not have to be concerned that much with appearance. The ones I add in the rear of the room will be visible and will need to be covered to avoid being a sore thumb.

Yup. I know what I'm going to do, but I have to get my molding and trim up before I can do it.

It took me a couple of weeks but I think I've made it through this whole thread. Now I may have missed it but what other solutions besides REW are available to take acoustic measurements; and of those, which do the pros use?

I see the DEQ has RTA built in measurement but it looks limited to the tiny LCD.

I'm a pro and I use REW. Hey, it's fabulous and it's free. Why even look further?

--Ethan

Mark Seaton gave you the right answer too. As I explained on the phone, there are three problems with what you propose:

1) Rigid fiberglass only one inch thick does not absorb to a low enough frequency. I suggest two inches thick as a minimum. Otherwise all you'll absorb is treble and a little midrange. If your fabric track is only one inch deep, attach it to firring strips to bring it our farther and make a deeper cavity to accommodate two-inch fiberglass (or two layers of one inch).

2) Absorbing the lower half of a wall up to ear level kinda misses the mark. It covers the very bottom of the wall where absorption is not needed, and leaves the part just above your ears reflective. Sound leaves loudspeakers in an arc, spreading upward, downward, and outward the farther it goes. So absorption should extend to at least a foot above ear level on the side walls.

3) Covering a 4-foot high swath around the room centered at ear level is fine, but covering all of the walls from floor to ceiling is definitely too much absorption. Even a band going all around the room is probably too much since what really matters are the reflection points.

--Ethan

Hi Ethan I tooked advantage of your comments above, I have a small room and I have some rigid fiberglass 24x48x2 horizontally below ear levels in my sidewalls and I remove them and scattered them 1 foot above ear levels or just about and I am glad I did because I am happy with the results. I removed every rigid fiberglass I have below ear levels except at the front wall.

And thank you for always sharing...:)

I'm a pro and I use REW. Hey, it's fabulous and it's free. Why even look further?

--Ethan

I'm very well aware of the unintended consequences that come with application level systems. As little as a java update could skew things or prevent it from working completely. I prefer appliance level reliability and longevity of service.

Of course there's always the line of thinking that you simply don't perform any software upgrades but what happens when you have a drive failure and some facet of your application isn't available anylonger?


Its probably not an issue but old habits die hard.

I'm a pro and I use REW. Hey, it's fabulous and it's free. Why even look further?

Me too. I've never had a problem.

Frank

REW is not just any old Java program. John Mulcahy, its author, is one seriously smart guy with a lot of experience in signal processing.

- Terry

Hope I am not breaking any forum rules with the following. I meant to note this experience last week:

A big call-out to GIK for outstanding service (and in this day and age - even average service is hard to find)

Two weeks ago;
- late on a Tuesday afternoon; I ordered some GOM
- To my surprise I had the GOM on my Illinois doorstep on Thursday

Just wanted to share an Excellent experience with GIK (and A Thanks to Frank as well)!

I'm very well aware of the unintended consequences that come with application level systems. As little as a java update could skew things or prevent it from working completely. I prefer appliance level reliability and longevity of service.

Of course there's always the line of thinking that you simply don't perform any software upgrades but what happens when you have a drive failure and some facet of your application isn't available anylonger?

Its probably not an issue but old habits die hard.


And on the other extreme of things are companies who see legit products but are either unable to continuously support legacy systems or purposely do not forcing you to pay to upgrade. This particular freeware does seem to work really awesome, at least what playing I've done (I don't have a microphone yet).

REW is not just any old Java program. John Mulcahy, its author, is one seriously smart guy with a lot of experience in signal processing.

- Terry

I have absolutely no doubt about the app being fantastic. Like I said earlier, old habits die hard. I just get a nagging feeling I'm doing it the wrong way. I probably shouldnt worry too much since I have a dedicated REW laptop. Perhaps I'll satiate myself by getting a better microphone. I see the ECM8000s are about $50. Whats a good mic preamp to go with it?


And just for curiosities sake, what would you guys be using if REW were not available?

And just for curiosities sake, what would you guys be using if REW were not available?
Other similar products, in no particular order:

ETF
Arta
WinMLS
Easera
DIRAC
TEF20 Analyzer with Sound Lab MLS

- Terry

what would you guys be using if REW were not available?

I started with ETF which works well, but it's not quite as full-featured as the latest version of REW:

Using ETF (http://www.realtraps.com/art_etf.htm)

there's always the line of thinking that you simply don't perform any software upgrades but what happens when you have a drive failure and some facet of your application isn't available anylonger?

I have a separate drive partition where I save all downloaded programs, and of course that's backed up on multiple drives in different locations. Likewise, I keep only Windows and programs on my C: drive, and I use Ghost to make image backups. So no matter what happens to C: I can be back and running in 15 minutes. The value of keeping all data separate from the OS and programs is the OS drive rarely changes and can be backed up less often. And if you do have to restore, none of your data is "restored" to older versions too.

--Ethan

There is also backup/sync freeware such as SyncBack (http://www.2brightsparks.com/downloads.html#freeware) that is powerful and easy to use. Upgrading to a registered version in inexpensive, but I have found that the freeware version does everything I need. There is also a PowerToy called SyncToy (http://www.microsoft.com/prophoto/downloads/synctoybeta.aspx) that is free from Microsoft. With apps like these and the low low cost of storage, internal, external and solid state, there is no reason that any data is ever lost.

Hey, I use SyncBack too! I liked it so much I sent them the money for the Pro version a few years ago. But I prefer the freeware version so I still use that. I was glad to give them the money anyway though. It's a great program. I have more than a dozen profiles for all the data types and multiple round-robin destinations I back up to.

--Ethan

Hey, I use SyncBack too! I liked it so much I sent them the money for the Pro version a few years ago. But I prefer the freeware version so I still use that. I was glad to give them the money anyway though. It's a great program. I have more than a dozen profiles for all the data types and multiple round-robin destinations I back up to.

--Ethan
Agreed, Ethan. I do that for quite a few little utilities I find useful.

A few observations with my first acoustic journey. I bought a pair of GIK tri traps and a pair of ATS 4" 24x48 panels and a single 24x24. I put the GIKs in the front wall corners and the 24x48's at the first reflection points of the speakers on the wall. The 24x24 behind the center channel. There is only 18 inches of bare wall between the speakers and the giks next to my 60 inch plasma and the speakers are facing the corners toed in. The ATS stuff seems much better built than the Tri Traps which seem like I would have been able to make with stuff around the house. The tri traps almost have no weight to them. Maybe they forgot to put the acoustic filling in? few questions

1) If I breath in hard with my nose I still get flutter echo in my room. So its still very live. I need more panels in my 11x16 room? Im sitting 8 feet away from the front wall and the back wall is a open closet full of clothes.
2) Where should I put these panels? Ceiling? The first reflection points of the front l/r are covered.
3) The tri traps may have tightened the bass up slightly but are the effective in deadening the wall space behind my speaker?
4) everyone talked about how acoustic treatments would make the biggest difference but the soundstage is still smeared and busy. Do I just need MORE treatment?
Thanks

First reflection points include ALL first reflection points. So yes ceiling I would say is a must.

Does it hurt your nose to do that because I physically can't make a noise loud enough with my nose to cause an echo I just can't seem to do it.

3/ - yes they deaden

4. ~ Hit all the first reflection points first then work on other suggestions.

notoriousmatty (http://www.avsforum.com/avs-vb/member.php?u=7770549),

Got a photo or three of the room and panel placement? Seems unlikely a single panel on the side wall could get all three first reflection points for the front speakers, but seeing a photo might explain how that is working.

A few observations with my first acoustic journey. I bought a pair of GIK tri traps and a pair of ATS 4" 24x48 panels and a single 24x24. I put the GIKs in the front wall corners and the 24x48's at the first reflection points of the speakers on the wall. The 24x24 behind the center channel. There is only 18 inches of bare wall between the speakers and the giks next to my 60 inch plasma and the speakers are facing the corners toed in. The ATS stuff seems much better built than the Tri Traps which seem like I would have been able to make with stuff around the house. The tri traps almost have no weight to them. Maybe they forgot to put the acoustic filling in? few questions

1) If I breath in hard with my nose I still get flutter echo in my room. So its still very live. I need more panels in my 11x16 room? Im sitting 8 feet away from the front wall and the back wall is a open closet full of clothes.
2) Where should I put these panels? Ceiling? The first reflection points of the front l/r are covered.
3) The tri traps may have tightened the bass up slightly but are the effective in deadening the wall space behind my speaker?
4) everyone talked about how acoustic treatments would make the biggest difference but the soundstage is still smeared and busy. Do I just need MORE treatment?
Thanks
Look into "diffusion."

I understand that the "thinking" on acoustical treatments is evolving with LEDE being completely out the window now for multichannel listening. Herein lies my dilemma. When I originally build my room, it was recommended that I completely line the cavity behind my false wall with 2" Linacoustic, line the frame around the AT screen with the same material and to install a 2" fiberglass mask over the center channel's baffle - cutout sufficiently for the drivers of course. My screen at the time was a micro-perfed Firehawk and comb filtering was a problem with the aforementioned treatment mitigating it. (Nonetheless, I could never get the center channel EQ'd correctly.)

Now I have moved to a woven AT screen and the material I am reading is making me rethink my treatments behind the wall. (OK, the material - Toole and Holman specifically - actually has me considering swapping my front left and right absorbers for diffusors, but that should probably be the subject of another post.)

Keeping, of course, the SSC bass traps there and the 'glass directly behind each front speaker for first reflection point reasons, should I remove the Linacoustic and leave the wall untreated? Remove and replace the Linacoustic with diffusors?

Is comb filtering from sound reflections in the screen/false wall cavity not an issue with woven screens?

I will probably cross-post this question one or two other places - the SMX thread being one.

TIA!

Now I have moved to a woven AT screen and the material I am reading is making me rethink my treatments behind the wall. (OK, the material - Toole and Holman specifically - actually has me considering swapping my front left and right absorbers for diffusors, but that should probably be the subject of another post.)

Keeping, of course, the SSC bass traps there and the 'glass directly behind each front speaker for first reflection point reasons, should I remove the Linacoustic and leave the wall untreated? Remove and replace the Linacoustic with diffusors?

This change would affect the reverberation times of the room. If the latter are already at good levels and uniform over frequency, I wouldn't mess with it.

As for first reflection point from the front wall, this depends on the distance of the speakers to the front wall. This reflection will not cause image shifting or other distortion of the front sound stage, as will side wall reflections. It has other potential consequences.

Even though your speakers are facing forward, they will typically be very omnidirectional up through at least 250 Hz. A 1/4 wave reflection at 250 Hz and lower corresponds to a speaker to wall distance of about 1 foot or more. If your speaker distance is roughly 1.5 feet or less, then 2+ inches of fiberglass may be effective at treating this potential wave cancellation problem. This is easy to test by temporarily covering the area behind the speaker with something hard, like plywood, and seeing if a dip appears at the expected 1/4 wave frequency.


Is comb filtering from sound reflections in the screen/false wall cavity not an issue with woven screens?

It is less of an issue, but can still manifest itself as ripple at the highest frequencies.

- Terry

This has got me thinking. I have skimmed the thread but have not found an answer for my situation.

I am going to be building a screen wall for my theater, about 18 - 24" deep with a woven screen. I am not going to place the mains behind the screen they will be to the side of the screen in recesses in the screen wall. The center will be on a shelf the same height as the bottom of the screen, directly behind it. I will probably place the sub on the floor with GOM material in front of it.

Should I be treating anything behind the screen wall? Right now the main wall is just unfinished drywall, and I was going to also construct the screen wall of drywall also. I see some people are using fibreglass along the main wall. Is this simply insulation, or is there a special product for it?

I don't imagine I'll get a whole lot of resonance with the sub 2" behind GOM and the center 2" behind the screen, so maybe I don't really need anything back there?

Should I be treating anything behind the screen wall? Right now the main wall is just unfinished drywall, and I was going to also construct the screen wall of drywall also.
Generally, behind the screen wall is an excellent place to stash acoustic treatment, without having to worry about the way it looks. Corner bass traps constructed of semi-rigid fiberglass often fit well here.

- Terry

Generally, behind the screen wall is an excellent place to stash acoustic treatment, without having to worry about the way it looks. Corner bass traps constructed of semi-rigid fiberglass often fit well here.

- Terry

Is there a product for this, or is it as simple as cramming some insulation down there? :rolleyes:

This change would affect the reverberation times of the room. If the latter are already at good levels and uniform over frequency, I wouldn't mess with it.

As for first reflection point from the front wall, this depends on the distance of the speakers to the front wall. This reflection will not cause image shifting or other distortion of the front sound stage, as will side wall reflections. It has other potential consequences.

Even though your speakers are facing forward, they will typically be very omnidirectional up through at least 250 Hz. A 1/4 wave reflection at 250 Hz and lower corresponds to a speaker to wall distance of about 1 foot or more. If your speaker distance is roughly 1.5 feet or less, then 2+ inches of fiberglass may be effective at treating this potential wave cancellation problem. This is easy to test by temporarily covering the area behind the speaker with something hard, like plywood, and seeing if a dip appears at the expected 1/4 wave frequency.


It is less of an issue, but can still manifest itself as ripple at the highest frequencies.

- Terry
Ummm, yes, thank you, Terry. Seems I should take my own advice and do some measurements before doing anything. FWIW, my front speakers are Omnimount'ed onto the front wall with mere inches between the wall and the cabinet.

I am going to be building a screen wall for my theater, about 18 - 24" deep with a woven screen. I am not going to place the mains behind the screen they will be to the side of the screen in recesses in the screen wall. The center will be on a shelf the same height as the bottom of the screen, directly behind it.
Just curious, slider33, why acoustical transparent screen if you are not going to place LCR behind it? As far as syncing the picture and the sounds, that is the bee's knees.

Is there a product for this, or is it as simple as cramming some insulation down there? :rolleyes:
703 is popular. 2" or 4". This page will enable you to shop and possibly find a lesser expensive alternative. 3.0 pcf is the spec to look for.

http://www.bobgolds.com/AbsorptionCoefficients.htm

Is there a product for this, or is it as simple as cramming some insulation down there? :rolleyes:
What pepar said.

- Terry

Just curious, slider33, why acoustical transparent screen if you are not going to place LCR behind it? As far as syncing the picture and the sounds, that is the bee's knees.

I have thought about that, and it is a viable option as well. I mainly wanted the mains on the sides for a "business" look, and didn't want to place the center under a regular screen as it would be quite low. Is it really much better to run all the LRC behind it? In this case I would just make the whole screen wall GOM around the screen. I really don't even know if I can fit the mains on the sides anyway as I only have about a foot of space to play with (screen and speakers are about 11' wide combined, room is 12'). Maybe if I do this I can go up a screen size also :D.

703 is popular. 2" or 4". This page will enable you to shop and possibly find a lesser expensive alternative. 3.0 pcf is the spec to look for.

http://www.bobgolds.com/AbsorptionCoefficients.htm

Thanks again

I have thought about that, and it is a viable option as well. I mainly wanted the mains on the sides for a "business" look, and didn't want to place the center under a regular screen as it would be quite low. Is it really much better to run all the LRC behind it? In this case I would just make the whole screen wall GOM around the screen. I really don't even know if I can fit the mains on the sides anyway as I only have about a foot of space to play with (screen and speakers are about 11' wide combined, room is 12'). Maybe if I do this I can go up a screen size also :D.
Oh yeah!

And for timbre/equalization purposes, locating all three front speakers behind the screen is a plus. Having an AVR or pre/pro with an "automatic" equalization system - such as Audyssey - removes the hassle of tweaking. As you mention, this would also get your L&R away from the wall, too. Check the my home theater website (linked in my sig).

Once you've had LCR behind the picture, you'll have trouble enjoying the home theaters of your mates who do not. :)

Is the rigid fiberglass in the link you posted earlier readily available at most home stores? I have been looking for the 703 on Home Depot's site and I cannot find it on there.

They do have sound absorbent insulation though (several brands). Is this the same idea, just that it can't be easily drilled/stuck to the wall?

Is the rigid fiberglass in the link you posted earlier readily available at most home stores? I have been looking for the 703 on Home Depot's site and I cannot find it on there.

They do have sound absorbent insulation though (several brands). Is this the same idea, just that it can't be easily drilled/stuck to the wall?
The pink fluffy stuff sold by home improvement stores would do the job. What you need is sold through HVAC insulation channels. This company (http://www.spi-co.com/index.html) is popular. Seattle and Tuckwila have locations.

The pink fluffy stuff sold by home improvement stores would do the job. What you need is sold through HVAC insulation channels. This company (http://www.spi-co.com/index.html) is popular. Seattle and Tuckwila have locations.

Excellent, thank you for your time.

Hey folks, I need some quick opinions here. As mentioned earlier in this thread, I'm doing a home theater reno in a living room.

One issue with this room is that it's a living room right below our bedroom.
Sometimes my wife will go to bed earlier and I want to limit the sound traveling through the floor upstairs into the bedroom. For various reasons we can't do any major acoustic isolation treatment, but what I want to do is at least PRESERVE the isolation I had before this home theater reno. There wasn't too much sound transfer before the reno and my wife never had any problems with the sound at night. (I don't play it loud anyway).

So my fear has been introducing any more pathways for sound to intrude through the ceiling. Which is one reason we dropped the ceiling to add pot lights, rather than risk poking holes into the existing ceiling to add the pot lights.

BUT...of course with all the running of wire and construction, contractors have had to poke many holes in the walls and ceiling. So I have a question on two issues:

1. What should we do to acoustically seal the various holes? Many of them will be re-dry-walled, but some, like in one of the pictures I'm posting, have wires coming out of them.

2. The Screen Wall. As you can see the screen wall has had the drywall taken off. Originally we planned to simply dry-wall it up again (it was being straightened for the screen). But instead, now we plan to fill it with absorptive material, so behind and around the screen will act as an acoustic absorption. (A "dead wall"). So no drywall. But I'm concerned that this could be a route for sound to travel up the cavity into the bedroom above.

Should I be worried about this, given the cavity will be filled with absorption?
Or do I need to somehow have a seal made at the top of the open wall. It's been suggested perhaps to seal it by using spray-in foam. Or perhaps create a dry-wall seal? Any advice?

Thanks. (Please see pictures).

http://img15.imageshack.us/img15/4798/screenwallopenedup.jpg

Looking up into screen wall top opening. Above this is our bedroom. Do I need to create a seal up there, or will stuffing the whole wall with absorption be stopping the sound enough as it is?:

http://img155.imageshack.us/img155/5126/lookingintoscreenwall.jpg

A hole in the ceiling where some wires come out. How to acoustically seal this?

http://img242.imageshack.us/img242/5761/holeinceiling.jpg

Anyone?

Hang in there Rich,

Experts here are really generous maybe they are just outhere researching for you...too bad I am no expert.

Peter

Anyone?
Almost nothing you can do will prevent the sound - the bass - from being transmitted though the building elements to the adjacent spaces. :)

2. The Screen Wall. As you can see the screen wall has had the drywall taken off. Originally we planned to simply dry-wall it up again (it was being straightened for the screen). But instead, now we plan to fill it with absorptive material, so behind and around the screen will act as an acoustic absorption. (A "dead wall"). So no drywall. But I'm concerned that this could be a route for sound to travel up the cavity into the bedroom above.

Should I be worried about this, given the cavity will be filled with absorption?

Yes, be very worried. In fact, don't do it! Even with a lot of absorption, much sound will travel right up to the second floor. The porous absorption material will not contain the sound.

Instead, put up at least one layer of drywall (2 is better) to make a proper 2-leaf wall with fiberglass-filled airspace. Put the screen acoustical absorption in front of this inner drywall.

- Terry

Yes, be very worried. In fact, don't do it! Even with a lot of absorption, much sound will travel right up to the second floor. The porous absorption material will not contain the sound.

Instead, put up at least one layer of drywall (2 is better) to make a proper 2-leaf wall with fiberglass-filled airspace. Put the screen acoustical absorption in front of this inner drywall.

- Terry

Thank you VERY much for the response Terry. The idea of not drywalling and instead filling the cavity with acoustic absorption material was actually suggested to me by the company doing my room acoustic treatments. But I was obviously still worried about sound transfer to the upstairs and your post adds to that concern.

If you don't mind:

1. So, in reference to the second last picture in my post, looking up into the wall cavity toward the ceiling, would it not be possible to create some sort of inner seal at the point were the drywall starts in that picture? Just to stop the sound travelling upward?

2. If I go the drwall route you suggest, I'm not sure where the drywall layer would go. If we just drywalled it like normal, the drywall would be placed over the wall studs. However, for various reasons, I don't have room to push the screen out any more into the room, so I won't have room to thicken the wall with acoustic material overtop a normal drywall application.
Which is why we were thinking of leaving off the drywall, giving us room to place acoustic material between the studs.

In your drywall suggestion, where would the drywall be placed? Some sort of layer sort of set back into the studs somewhat, with a layer of acoustic material overtop that behind the screen?

We are right at the stage of doing the screen wall so advice like yours is very
pertinent. It will help me decide if I bother putting acoustic material into the screen wall or (possibly make my life easier and) just have the screen wall drywalled and hang the screen.

BTW, we have a 24" wide by 6" deep drop down bulkhead built down from the room ceiling, so we can put acoustic absorption above the screen wall, and some over the general seating area as well. I was just thinking that making the screen wall "dead" would help too.

Many thanks!!!!!!

Thank you VERY much for the response Terry. The idea of not drywalling and instead filling the cavity with acoustic absorption material was actually suggested to me by the company doing my room acoustic treatments. But I was obviously still worried about sound transfer to the upstairs and your post adds to that concern.

If you don't mind:

1. So, in reference to the second last picture in my post, looking up into the wall cavity toward the ceiling, would it not be possible to create some sort of inner seal at the point were the drywall starts in that picture? Just to stop the sound travelling upward?

Maybe, but not having a standard interior wall covering such as gypsum board over studs is not what I'd consider a "best practice" for either home theater or general residential construction. I wouldn't offer any advice along those lines. Depending on where you live, it may not even be permitted by local building code.


2. If I go the drwall route you suggest, I'm not sure where the drywall layer would go. If we just drywalled it like normal, the drywall would be placed over the wall studs. However, for various reasons, I don't have room to push the screen out any more into the room, so I won't have room to thicken the wall with acoustic material overtop a normal drywall application.

You don't have a couple of inches? There are numerous compromises required in building a home theater. I'm afraid this is one of them. :(

- Terry

Ok Terry, thank you. That's helpful.

Any comments about creating seals for the other holes in my ceiling from running wires? You can see one of these holes in my last photo.

Ok Terry, thank you. That's helpful.

Any comments about creating seals for the other holes in my ceiling from running wires? You can see one of these holes in my last photo.

If air can get through, high frequency sounds can get through.

If physical elements are touching (like studs and drywall) then big thumping bass wil transfer throughout the house.

It is VERY worth it to loose as many as six inches on all sides to effectively build space between the theater room and the rooms surrounding it.

If air can get through, high frequency sounds can get through.

If physical elements are touching (like studs and drywall) then big thumping bass wil transfer throughout the house.

It is VERY worth it to loose as many as six inches on all sides to effectively build space between the theater room and the rooms surrounding it.

Thank you. But full isolation is simply impossible in my situation (aside from financially). It's a living room and it has a grand, open doorway (no doors) with columns from the 1920s. There is no sealing off this room.

But it's been ok for many years in terms of not too much sound escaping to the upstairs bedroom, so as I said I'm just concerned about changes to the room (new holes/openings) creating additional sound leakage, which might push what has been acceptable to unacceptable noise leakage.

Like I said, almost nothing you can do will prevent the sound - the bass - from being transmitted though the building elements to the adjacent spaces.

Hi All,

Sorry, I searched this LONG thread first, but I can't seem to find a good explanation for my present concerns.

I am almost finished covering my light colored walls and ceiling with dark drapes/fabric for the purpose of creating a bat cave like environment for my theater. I'm going with fabric as a temporary solution because it's easily reversable and I may totally overhaul the theater in the not to distant future. Anyway, while trying so hard to improve my viewing environment, I think I may have just compromised my listening environment.:eek: The drapes and fabrics of choice are made of cotton, polyester and acrylic. My current room is only about 12' x 11' with a 7-7.5' tiled drop ceiling. And, I also have some corner bass trapping and acoustic panels in place.

Did I just create a "dead" listening space??? I apologize in advance if this sounds a bit novice.:o

Thanks...

Did I just create a "dead" listening space??? I apologize in advance if this sounds a bit novice.:o

No. The fabric, per se, has very little sound absorption unless it is HEAVY. For example, a very heavy velour fabric (40 ounces/square yard!) has significant absorption starting above 1 kHz. It reaches its peak at around 10 kHz.

Typical thin cotton and synthetic should have little acoustical effect, and are relatively transparent. Which means that you can always hide additional porous absorption behind it if you need to do so.

- Terry

No. The fabric, per se, has very little sound absorption unless it is HEAVY. For example, a very heavy velour fabric (40 ounces/square yard!) has significant absorption starting above 1 kHz. It reaches its peak at around 10 kHz.

Typical thin cotton and synthetic should have little acoustical effect, and are relatively transparent. Which means that you can always hide additional porous absorption behind it if you need to do so.

- Terry

Great insight Terry--thanks for chiming in as you and other professionals do! Much appreciated... :)

No. The fabric, per se, has very little sound absorption unless it is HEAVY. For example, a very heavy velour fabric (40 ounces/square yard!) has significant absorption starting above 1 kHz. It reaches its peak at around 10 kHz.

Typical thin cotton and synthetic should have little acoustical effect, and are relatively transparent. Which means that you can always hide additional porous absorption behind it if you need to do so.

- Terry

Great! Thanks for that very helpful info...

Btw, I was most concerned with the black suede drapes I'm using on the side walls, because they are actually "moderately" thick blackout drapes with a 100% polyester surface and a 100% acrylic backing.

Any thoughts? Thanks...

Did I just create a "dead" listening space???

Terry already gave you good answers. I'll add that a home theater in a small room should be mostly on the dead side. That removes the "small room sound" which in turn makes movie sound tracks sound larger. But you need more than thin curtains to achieve this.

--Ethan

Terry already gave you good answers. I'll add that a home theater in a small room should be mostly on the dead side. That removes the "small room sound" which in turn makes movie sound tracks sound larger. But you need more than thin curtains to achieve this.

--Ethan

Exactly the answers I was hoping for.

Thanks Ethan and Terry...

I've been having the same anxiety about ending up with too dead a room. Mine's a living room/home theater. The company who will be applying a fabric covering over a 12 x 12' portion of the ceiling, wants to put a 1" (or is it 1/2"?) layer of foam core on to the ceiling, then put the fabric over it. With the big thick rug, many curtains and huge sofa in a relatively small room (15 x 13') I'm worried this will make the sound too dead. I know it should help with some first ceiling reflections, but at the same time I don't want the room to "sound" odd, like entering a recording studio.

Foam core!? What specific product. This smells bad already.

Well, I had some interesting results today. I made a 5.5" thick 2'x4' bass trap today and tried it in a few different spots. It seemed to only help very little in the 70-90Hz. range. There was also no real visable benefit in the waterfall graphs either.

Graph response from on top of the desk:

http://img30.imageshack.us/img30/2710/thicktrapondesk.jpg (http://img30.imageshack.us/my.php?image=thicktrapondesk.jpg)

Graph from opposite front corner:

http://img194.imageshack.us/img194/6852/thicktrapkitchencorner.jpg (http://img194.imageshack.us/my.php?image=thicktrapkitchencorner.jpg)

Final graph next to couch:

http://img194.imageshack.us/img194/1122/thicktrapleftsideofcouc.jpg (http://img194.imageshack.us/my.php?image=thicktrapleftsideofcouc.jpg)

Here is a link to one of my posts with pictures and layout so you can understand the trial placements:

http://www.avsforum.com/avs-vb/showthread.php?p=16359511#post16359511

Any thoughts on the results?

:confused:

Well, I had some interesting results today. I made a 5.5" thick 2'x4' bass trap today and tried it in a few different spots. It seemed to only help very little in the 70-90Hz. range.
...
Any thoughts on the results?

:confused:
I think your expectations may be too high for these frequencies and a single 2'x4' corner bass trap. You need a lot more coverage to have a significant effect as low as 70 Hz.

But I would start by calibrating your sub with respect to your mains. It is pretty high.

- Terry

Foam core!? What specific product. This smells bad already.

Maybe I got that wrong. I'm pretty sure he mentioned some kind of "core"...and I think he mentioned "Rocksil" (sp?)

But I would start by calibrating your sub with respect to your mains. It is pretty high.

It is high due to house curve and to get 30Hz. to "sound" the same volume as 100Hz. What is interesting is, when I play the receiver's test tones, the subs are 1 dB lower than each main (74dB versus 75dB.).

I think your expectations may be too high for these frequencies and a single 2'x4' corner bass trap. You need a lot more coverage to have a significant effect as low as 70 Hz.

I figured by testing the two different corners, I would get an average of the two if I had two traps to place. Also, I would have been fine with no change in the frequency response, but have a noticeable change some where in the waterfall. Besides, those were the only two corners that I could possible put anything substantial for a bass trap. The last corner available has a large clock and chair in it. There is no room for anything bigger than 1' wide.

From the testing results, I will probably get "more bang for my buck" focusing on broadband traps some more. I have not done anything on the ceiling yet! :) Basically like you said previously:

With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways. :) Like the Energizer Bunny, it keeps on going! Especially low frequency sound. This means that subwoofer frequencies can easily escape into larger spaces, and may not be an issue. Higher frequencies, on the other hand, are more readily trapped between parallel walls, and may create problems.

Another question for you. What might happen if I place a broadband trap between the two M&K tripoles on the rear wall? Is that a bad idea based on their design?

Thanks for your help and comments!

I figured by testing the two different corners, I would get an average of the two if I had two traps to place.
Which corners did you try? Can you show us on the diagram you posted in the other thread?

- Terry

Which corners did you try? Can you show us on the diagram you posted in the other thread?

- Terry

Here is the layout again:

http://img90.imageshack.us/img90/2522/layoutn.jpg (http://img90.imageshack.us/my.php?image=layoutn.jpg)

I tried the corner in the far upper left in the dinning area and the corner in the far upper right where the desk is. I placed the trap about mid way up the wall and had it straddling the wall-wall corner. As close to a 45 degree angle as I could. The area that showed the good result was on the left side of the couch/table straddling the wall-floor corner at a 45 degree angle. I already have a 3.5"x2'x3' bass trap on the right side of the couch/table between them and the clock on the floor.

Do you guys recommend treating first reflection points then running audyssey if I don't have the budget for bass traps yet? Or just leave audyssey off? Also the same question goes for when I do get the bass traps, should I run audyssey afterwards or just try to get as close to optimal as possible with absorption? I tried audyssey before I treated the reflection points and to be honest it sounded like my speakers were turned into a bullhorn, it sounded really weird.

Onkyo 605 and polk rti speakers with a bic h100 sub.

Do you guys recommend treating first reflection points then running audyssey if I don't have the budget for bass traps yet? Or just leave audyssey off? Also the same question goes for when I do get the bass traps, should I run audyssey afterwards or just try to get as close to optimal as possible with absorption? I tried audyssey before I treated the reflection points and to be honest it sounded like my speakers were turned into a bullhorn, it sounded really weird.

Onkyo 605 and polk rti speakers with a bic h100 sub.

Treatments (as many as you can afford) -- then run audyssey, after every change of traps or speaker or furniture position.

Follow the tips in the Audyssey thread to get the best results.

I tried the corner in the far upper left in the dinning area and the corner in the far upper right where the desk is.
Hmm, I suspected this. Remember when I said,

With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways.

Well, this is particulary true of the lowest bass frequencies. Subwoofer frequencies don't "see" the dining area as much by way of a room. It is too open for them to generate the strongest room modes at the wimpy dining room corner-shapes which you consider the room boundaries. Big bass waves will not be confined by these (at least horizontally), but blast through into the adjacent spaces. If there were doors enclosing the dining area, things would be very different. But without doors, these wave more likely consider all all the space open to it the "room." This has a larger and more complex shape than than the dining area rectangle.

So the important acoustical low frequency corners of the actual room are probably not the little ones in the dining area, but the two at the right-most part of the playroom, and those somewhere in the kitchen and the foyer, which you haven't completely shown, and maybe corners in whatever is beyond the bottom left door out of the dining area.

- Terry

Treatments (as many as you can afford) -- then run audyssey, after every change of traps or speaker or furniture position.

Follow the tips in the Audyssey thread to get the best results.

OK I'll check that thread out thanks.

OK I'll check that thread out thanks.

Follow the link in my signature to see the Audyssey Setup Guide mentioned.

Mark

Follow the link in my signature to see the Audyssey Setup Guide mentioned.

Mark

Wow. Very nice, exactly the type of thing I was looking for. Very much appreciated.

Well, this is particulary true of the lowest bass frequencies. Subwoofer frequencies don't "see" the dining area as much by way of a room. It is too open for them to generate the strongest room modes at the wimpy dining room corner-shapes which you consider the room boundaries. Big bass waves will not be confined by these (at least horizontally), but blast through into the adjacent spaces. If there were doors enclosing the dining area, things would be very different. But without doors, these wave more likely consider all all the space open to it the "room." This has a larger and more complex shape than than the dining area rectangle.

So the important acoustical low frequency corners of the actual room are probably not the little ones in the dining area, but the two at the right-most part of the playroom, and those somewhere in the kitchen and the foyer, which you haven't completely shown, and maybe corners in whatever is beyond the bottom left door out of the dining area.

Terry,

First off, thanks for sticking with me and explaining things so us non-experts can understand. Your comments make total sense. The only interesting thing I will add is that when I walk around while playing filtered pink noise of 30-300Hz., the bass sounds heavy/boomy in those small dining area corners. More so than the kitchen and foyer. Also in the playroom, the far upper right corner is composed of all windows. Basically the entire playroom outer walls are windows. If I remember correctly, this means all the low Hz. are going to just pass through them. That in combo with the very open plan is probably why I cannot get my set-up to play lower than 15Hz. Would placing a trap in a corner constructed of windows really do anything? What about placing it in a door way? In a sense, to create a door and try to seal the other smaller spaces off.

Another question for you. What might happen if I place a broadband trap between the two M&K tripoles (a pair of K4's) on the rear wall? Is that a bad idea based on their design?

Thanks again for all your help.

Here is the layout again

The biggest problem I see is you have a reflecting wall right behind your head.

--Ethan

The biggest problem I see is you have a reflecting wall right behind your head.

--Ethan

I have started addressing that with this panel (listening ear level is about in-line with the top of the couch cushions):

http://img90.imageshack.us/img90/1363/basstrapmeas02.jpg (http://img90.imageshack.us/my.php?image=basstrapmeas02.jpg)

But I am also wondering, what might happen if I place a broadband trap between the two M&K tripoles (a pair of K4's) on the rear wall? Is that a bad idea based on their design?

For what it's worth, if this were my space, I'd pull the couch out from the wall enough and place the rear surrounds *behind* the couch firing UP. Our bedroom system is set up that way and it is the only way to get the proper surround effect.

For what it's worth, if this were my space, I'd pull the couch out from the wall enough and place the rear surrounds *behind* the couch firing UP. Our bedroom system is set up that way and it is the only way to get the proper surround effect.

Ideally if space and WAF allowed, the couch would be pulled away. Unfortunately, there is not much space and the WAF factor is more in charge than I. :o I am lucky I am getting to do some panels at all. She said they had to blend in as much as possible. It has not been easy trying to duplicate a custom wall treatment on fabric! :eek:

Ideally if space and WAF allowed, the couch would be pulled away. Unfortunately, there is not much space and the WAF factor is more in charge than I. :o I am lucky I am getting to do some panels at all. She said they had to blend in as much as possible. It has not been easy trying to duplicate a custom wall treatment on fabric! :eek:
:)

To jump backward a bit....

Doing one corner then another is still giving you way too little coverage to get any kind of real idea of what you're going to get. As Terry said, you simply need some thickness and size to deal with the bottom end to have a significant impact for either frequency response and/or decay time.

Bryan

Hi,
This is my first post and i am new to acoustical treatments. I have a media room 13'x10'x8'. The below image shows my media room setup. I will be purchasing six 2'x4' 2" panels(Owens Corning 703). Can anyone please help me with the placements of these panels in the room? Also is my speaker setup correct?

http://lh3.ggpht.com/_w1SsV6B4FtA/ShMH4N1j-II/AAAAAAAAFSM/PsqiI8k_24o/s800/Image3.jpg

thanks for the help

Hi,
This is my first post and i am new to acoustical treatments. I have a media room 13'x10'x8'. The below image shows my media room setup. I will be purchasing six 2'x4' 2" panels(Owens Corning 703). Can anyone please help me with the placements of these panels in the room? Also is my speaker setup correct?

http://lh3.ggpht.com/_w1SsV6B4FtA/ShMH4N1j-II/AAAAAAAAFSM/PsqiI8k_24o/s800/Image3.jpg

thanks for the help

Try to find your first reflection points, this is where you will install you panels. once in your seating area have someone with a full lenght mirror (cheap mirror usually found at wallmart or target) along the wall and when you can see the a speaker in the mirror that is a reflection point and this where you would mount a panel. Mark the midpoint of the panel and mount that to the height of the tweeter in the speaker. Find a reflection point for every seat, you may may surprised at how many panels you end up with. As for your speaker placement, looks good except try and move the sub to the front or side walls if you can otherwise you will get too much localization since its so close. Im sure others will chime in with their recommendations, good luck

Try to find your first reflection points, this is where you will install you panels. once in your seating area have someone with a full lenght mirror (cheap mirror usually found at wallmart or target) along the wall and when you can see the a speaker in the mirror that is a reflection point and this where you would mount a panel. Mark the midpoint of the panel and mount that to the height of the tweeter in the speaker. Find a reflection point for every seat, you may may surprised at how many panels you end up with. As for your speaker placement, looks good except try and move the sub to the front or side walls if you can otherwise you will get too much localization since its so close. Im sure others will chime in with their recommendations, good luck
If you have billiard skills, sit in each seat and visualize the line into the wall that produces a strike on the speaker. It's weird, but it worked for me. The mirror think is a PITA.

For your room, the wall just behind the couch will be the biggest challenge to achieving good sound. IMO. I would try to put 4" of 703 there bust behind the heads of listeners.

Hi,
This is my first post and i am new to acoustical treatments. I have a media room 13'x10'x8'. The below image shows my media room setup. I will be purchasing six 2'x4' 2" panels(Owens Corning 703). Can anyone please help me with the placements of these panels in the room? Also is my speaker setup correct?

The other guys have already nailed the placement advice, so I'll just add this: that's a pretty small room, and you're seated right up against the back wall. You're going to need some pretty significant bass trapping in there. Typical placement would be in the corners, on the back wall and on the front wall behind the speakers. The 2" panels will go along way toward dealing with short reflections, but they're not going to do a thing to help with the low end room modes, which will be the biggest problem by far in a room that size and shape.

Frank

Thanks a lot guys, I guess i will mount two on each side walls after finding the reflection points and may be two on the back walls. Or the best bet would be is to mount one near each corner and two on the side walls?

pepar: for the back wall maybe i will convert the two 2" into a 4" and mount it behind the sofa.
Weasel9992: I know the room is small, i wish i had a bigger room :(

Thanks a lot guys, I guess i will mount two on each side walls after finding the reflection points and may be two on the back walls. Or the best bet would be is to mount one near each corner and two on the side walls?

pepar: for the back wall maybe i will convert the two 2" into a 4" and mount it behind the sofa.
Weasel9992: I know the room is small, i wish i had a bigger room :(

If you put two up on the back wall you'll probably end up moving them in the near future. Then again, the back wall will be the closest boundary layer to your ears, so it makes some sense for now. 2" panels won't do anything much below 500Hz, so there's no need to bother with corner placement I would think.

Rooms that size work well all the time. You just have to think all the way through treating them is all...get the right stuff in the right places. :)

Frank

Here's an odd one. I hope someone has some advice.

In my home theater reno room we recently built down a ceiling bulkhead (just framed at this point). We had move the existing AC pipe a little. My contractor used some form of extension pipe material from, I think, Home Depot. Added about 2 1/2 feet of extension with this pipe and now the output is mounted in the bulkhead.

But just tonight, when our air-conditioning turned on (probably for the first time) I noticed that the sound coming from that newly mounted AC vent sounded odd. It seems to have picked up a rubber-pipe-like resonance, so instead of an atonal rush of air like all the rest of our vents, it's making more of a solid, musical note tone. I find it quite distracting.

Any suggestions? I was thinking maybe I was hearing this tone because, unlike the rest of the AC vents in our house the piping is currently exposed and the bulkhead has not been completed. Except that when I listen up close it's like I can hear the resonant tone coming right out of the vent, not from around the tube.

Any advice? Can I change the resonance of this tube? I know it's some cheap stuff; are there any alternatives likely to make this issue go away?

Many thanks.

Rich H,

I am no expert at AC installation but you might try replacing the new extension with a length of flex.

Remove the vent. Music still there?

Ideally if space and WAF allowed, the couch would be pulled away. Unfortunately, there is not much space and the WAF factor is more in charge than I. :o I am lucky I am getting to do some panels at all. She said they had to blend in as much as possible. It has not been easy trying to duplicate a custom wall treatment on fabric! :eek:

Pull the couch out, set a table behind for her favorite nick-knacks.

You could pile up some bass traps under it, invisibly, and perhaps just get thin high frequncy stuff on the wall behind your ears.

Here is a random internet photo of the idea, but not against a wall.



http://www.rickswoodworking.ca/images/table_couch_0993.jpg

Remove the vent. Music still there?

I wish I could do that easily to experiment but I can't. One end is now built into a valance over the screen area :( So I'm hoping for a likely solution, warranting taking the thing out.

But just tonight, when our air-conditioning turned on (probably for the first time) I noticed that the sound coming from that newly mounted AC vent sounded odd. It seems to have picked up a rubber-pipe-like resonance, so instead of an atonal rush of air like all the rest of our vents, it's making more of a solid, musical note tone. I find it quite distracting.
Like blowing over the top of a bottle? If so, then in effect that is what is happening somewhere in what you've added or across the opening to what you added. Somehow you need to interrupt the airflow across the "bottletop" or otherwise disturb the resonance. Picture in your mind what was added and "look" for where the bottletop might be.

Is there any fiberglass lining the ductwork?

It seems I misunderstood. I thought he said the new ductwork is making the noise. If it's the register then it should be a simple and easy fix. I put new registers (decorative) on mine that have no directional/shut-off 'baffles'. Nothing in them to generate noise at all.

It seems I misunderstood. I thought he said the new ductwork is making the noise. If it's the register then it should be a simple and easy fix. I put new registers (decorative) on mine that have no directional/shut-off 'baffles'. Nothing in them to generate noise at all.
I believe the new ductwork is making the noise. but the noise Rich described suggests that it is a resonance, not air turbulance from a grill.

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

I would not agree totally with the statement that "sound reflecting off a surface suffers timbre shift." It depends on the relative level, spectrum, delay and direction of the reflection. There is a fair amount of research (nicely summarized in Floyd Toole's book) that suggests reflections in typical furnished domestic rooms generally do little harm and, in fact, generally do some good (increases spaciouness, image widening, and intelligibility). Of course, some absorption is required and diffusion is good too. We advocate wide-band absorption and diffusion - which eliminates the use of 1 inch of foam or fiberglass: 3-4 inches is preferred. There is also evidence that we adapt to the room acoustics and the reflections in the multichannel recording (coming from the side/rear speakers) will dominate the spatial/timbre impressions you hear.

I just posted an article (http://seanolive.blogspot.com/2009/05/harman-international-reference.html) on my blog about Harman International Reference Listening Rooms used for listener training, critical listening and product testing. We made the acoustical treatment removable so we can test many of these controversial questions about the perceptual effects of room treatment on sound quality. Stay tuned.

I was in LA last week. I would have enjoyed seeing your rooms.

I agree "too dead" is a bane; but, diffusion and reflection strategies would need to have some basis in the quality of the off axis response of the speakers, yes?

We do adapt well to, or listening through, some acoustic issues. Is there any recent research (at Harmon) with respect to any resultant listener fatigue as a result?

Like blowing over the top of a bottle? If so, then in effect that is what is happening somewhere in what you've added or across the opening to what you added. Somehow you need to interrupt the airflow across the "bottletop" or otherwise disturb the resonance. Picture in your mind what was added and "look" for where the bottletop might be.

Is there any fiberglass lining the ductwork?

Thanks.

The noise only came about once the 2 1/2 foot extension tube was added, to extend the end/grill to a new location in the new ceiling bulkhead. I've bent the tube around while air is flowing through it wondering if it would affect the tone but it doesn't. It's just standard tubing (plastic, I think). No fiberglass.

I believe the new ductwork is making the noise. but the noise Rich described suggests that it is a resonance, not air turbulance from a grill.I read it the same as you did then. Sorry for the confusion.

Thanks.

The noise only came about once the 2 1/2 foot extension tube was added, to extend the end/grill to a new location in the new ceiling bulkhead. I've bent the tube around while air is flowing through it wondering if it would affect the tone but it doesn't. It's just standard tubing (plastic, I think). No fiberglass.
Perhaps, then, the tube's "mouth" is the bottletop and the air from the existing duct strikes it at such an angle so as to excite the column of air in the tube. Proof of that would be to shorten or lengthen (compress or stretch) the tube. If the tone changes pitch, then that's what it is.

I was in LA last week. I would have enjoyed seeing your rooms.

I agree "too dead" is a bane; but, diffusion and reflection strategies would need to have some basis in the quality of the off axis response of the speakers, yes?

We do adapt well to, or listening through, some acoustic issues. Is there any recent research (at Harmon) with respect to any resultant listener fatigue as a result?

Hi Dennis,
Next time you are in LA, let me know and I can arrange a visit to Harman. Yes, the off axis response should be factored into decisions on treatment but any good home theatre consultant worth his or her commission should be able to recommend loudspeakers that have good off-axis response.

I've done some recent work on room acoustic adaptation. It appears we adapt very quickly (a few seconds), but only up to a point. In the case where the room has a lot of high level late reflections (30-80 msec) listeners will not adapt to the room acoustics, and complain about it's excessive liveliness, loss in clarity,etc. I didn't measure fatigue but if listeners have to work harder to understand dialog/lyrics,etc it wouldn't surprise me if fatigue were not an issue.

at what point does superchunk bass traps become too small? I have several that are 17x17x24 that I use in the corners. I was thinking about making some for where the walls and ceiling meet that are 12x12x17. Is this becoming too small to make a significant difference? Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.

at what point does superchunk bass traps become too small? I have several that are 17x17x24 that I use in the corners. I was thinking about making some for where the walls and ceiling meet that are 12x12x17. Is this becoming too small to make a significant difference? Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.
No doubt about it, the shallower traps do not reach as low. But I haven't seen any comparisons between the different sizes. I think the conmventional wisdom is to make them as deep as possible . . and install as much as possible. Not sure about felt. GOM definitely works, and burlap is usually very open and will work as well.

Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.
I have measured light velour felt (7.5 oz.) from Jo-Ann, and it has no significant attenuation at low frequencies. Jo-Ann burlap is better only at frequencies much higher than the bass region. The latter is transparent enough to be used as speaker grill cloth.

- Terry

I have measured light velour felt (7.5 oz.) from Jo-Ann, and it has no significant attenuation at low frequencies. Jo-Ann burlap is better only at frequencies much higher than the bass region. The latter is transparent enough to be used as speaker grill cloth.

- Terry

Excuse me for not understanding but you are saying felt is ok for bass traps correct?

Excuse me for not understanding but you are saying felt is ok for bass traps correct?
Yes, certainly the light-weight felt which you are likely to encounter at a fabric store such as Jo-Ann. Heavy theatrical curtain felt is a different story.

- Terry

at what point does superchunk bass traps become too small? I have several that are 17x17x24 that I use in the corners. I was thinking about making some for where the walls and ceiling meet that are 12x12x17. Is this becoming too small to make a significant difference? Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.

12x12x17 is too small I'd say. 17x17x24 is the way we build them. That said, it's probably a lot better than nothing at all in the corners.

Frank

12x12x17 is too small I'd say. 17x17x24 is the way we build them. That said, it's probably a lot better than nothing at all in the corners.
Frank, have you worked with 24x24x34 and if so, what performance differences have you noticed/measured?

If there is enough space, would it be better to make the superchunks square instead of triangular? A 12" square column would have approx. the same volume as a 17 x 17 x 24 triangle trap.

If there is enough space, would it be better to make the superchunks square instead of triangular? A 12" square column would have approx. the same volume as a 17 x 17 x 24 triangle trap.
It would be better to make it triangular at 17x17x24.

It would be better to make it triangular at 17x17x24.

Why?

12x12x17 is too small I'd say. 17x17x24 is the way we build them. That said, it's probably a lot better than nothing at all in the corners.

Frank

the small ones were to go all the way around the ceiling, just trying to find out if it would even be worth it, i dunno, alot of trouble if no gains. i also wondered whether making my sides 24x24x34 would help considerably or just leave them at 17x17x24

I also thought about getting some of your 6" panel traps from gik and just hanging them from the ceiling but I only read about corners being important. I still cant figure out your coffee table and pillar traps, where do you put them to smooth bass response?

Why?
Don't know the scientific reason, but the design is a proven performer. Do some research - http://forum.studiotips.com/viewforum.php?f=8&sid=12eafe1193b31ec826f4cb76f7c6b9e4

I also thought about getting some of your 6" panel traps from gik and just hanging them from the ceiling but I only read about corners being important. I still cant figure out your coffee table and pillar traps, where do you put them to smooth bass response?

Ceilings are important too...it depends on the specific room and specific situation, but floor/ceiling standing waves can be just as big an issue as length related or width related ones.

Those traps (an others like them) can be deployed in a bunch of different places, but commonly they're put along the walls of a room, in the corners or on the front wall...anywhere you need trapping but don't want something that looks quite so much like an acoustic panel.

Frank

the small ones were to go all the way around the ceiling, just trying to find out if it would even be worth it, i dunno, alot of trouble if no gains. i also wondered whether making my sides 24x24x34 would help considerably or just leave them at 17x17x24
24x24x34 will absorb lower.

24x24x34 will absorb lower.

Yep. The point is, where corners are concerned the more square footage you can cover at greater depth, the better. Of course, that only works to a certain extent because you also have to be able to use the room...

Frank

Yep. The point is, where corners are concerned the more square footage you can cover at greater depth, the better. Of course, that only works to a certain extent because you also have to be able to use the room...

Frank

This would seem to suggest that a 24 x 24 square would absorb lower than a 24 x 24 x 34 triangle?

Yep. The point is, where corners are concerned the more square footage you can cover at greater depth, the better. Of course, that only works to a certain extent because you also have to be able to use the room...

Frank
:)

The OP mentioned them, so it seemed like an option. Space, or the lack thereof, is a big factor in the layout in a lot our our home theaters. And 24x24x34 corner traps are humongous.