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post #5671 of 10422 Old 01-13-2010, 12:47 PM
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Quote:
Originally Posted by Ethan Winer View Post

Wall-floor and wall-ceiling corners are good, and flat on the wall behind the screen can help too if you have at least 3 or 4 inches or more space.



Why are those corners walled off? Can you remove that?

--Ethan

no- it has to do with the overall design of the space - there is a full bathroom to the right of the h/t, and we needed space to enter the shower:ergo. angled wall.
the opposite wall holds a small closet, and was built as an "aesthetic".(balanced the room visually.)
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post #5672 of 10422 Old 01-13-2010, 12:52 PM
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ethan, the screen is mounted directly on the wall. i'd need to make standoffs to move it out. are there sound reasons to do so?
then the next question is 4" of what, and wall to wall, i presume.
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post #5673 of 10422 Old 01-14-2010, 07:57 AM
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I searched everywhere but can find the answer - is Owens Corning 703 a fire retardant material? I am planning to build panels for my room using these panels covered with GOM FR701 but want to make sure the panels themselves will not be a fire hazard.
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post #5674 of 10422 Old 01-14-2010, 08:40 AM
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Originally Posted by LotToLearn View Post

I searched everywhere but can find the answer - is Owens Corning 703 a fire retardant material? I am planning to build panels for my room using these panels covered with GOM FR701 but want to make sure the panels themselves will not be a fire hazard.

No, it is not. Panels are made with 703, flame tested and certified all the time.

Frank

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post #5675 of 10422 Old 01-14-2010, 11:34 AM
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Quote:
Originally Posted by yacht422 View Post

are there sound reasons to do so?

Yes, all rooms need plenty of bass trapping.

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then the next question is 4" of what, and wall to wall, i presume.

4 inches of rigid fiberglass. Even more at the bottom if possible, straddling the wall-floor corner fully from left to right.

--Ethan

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post #5676 of 10422 Old 01-14-2010, 07:05 PM
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ethan: many thanks!
walt
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post #5677 of 10422 Old 01-15-2010, 11:43 AM
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Some food for thought....

I've been reading Sound Reproduction by Floyd Toole and it says that bass traps using resistive absorption (ie: rigid fiberglass) placed at wall boundaries/corners are ineffective because those are high pressure regions. For fiberglass to be effective, it needs to be placed in high VELOCITY regions which work out to be away from wall boundaries. And placing fiberglass away from wall boundaries is not very practical.

So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window. He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.
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post #5678 of 10422 Old 01-16-2010, 06:48 AM
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Quote:
Originally Posted by pocoloco View Post

Some food for thought....

I've been reading Sound Reproduction by Floyd Toole and it says that bass traps using resistive absorption (ie: rigid fiberglass) placed at wall boundaries/corners are ineffective because those are high pressure regions. For fiberglass to be effective, it needs to be placed in high VELOCITY regions which work out to be away from wall boundaries. And placing fiberglass away from wall boundaries is not very practical.

So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window. He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.

well, those who are packing their corners are not just sticking a little there. many use the 17" face chunk design, and some have the luxury (of space) to use the 24" face. my understanding of why to trap the corner is that ALL modes are present there.

wishful thinking? yeah, maybe that's what cleaned up the overhang in my room that used to be present in the waterfalls.
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post #5679 of 10422 Old 01-16-2010, 07:19 AM
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Quote:
Originally Posted by pocoloco View Post

Some food for thought....

I've been reading Sound Reproduction by Floyd Toole and it says that bass traps using resistive absorption (ie: rigid fiberglass) placed at wall boundaries/corners are ineffective because those are high pressure regions. For fiberglass to be effective, it needs to be placed in high VELOCITY regions which work out to be away from wall boundaries. And placing fiberglass away from wall boundaries is not very practical.

So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window. He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.

He may be talking about removing the room modes rather than just decreasing decay time.
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post #5680 of 10422 Old 01-16-2010, 09:40 AM
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Quote:
Originally Posted by pocoloco View Post

So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window.

Not in this universe. My company's video Hearing is Believing shows a huge before/after change with a lot of bass traps, and in this case the traps aren't even straddling corners. Floyd is correct in theory, but in practice you don't have to put panels several feet out from the wall to make a huge improvement. The video above shows a very large improvement in the response and ringing to 40 Hz and below.

Quote:


He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.

Again, he is wrong - and easily proven wrong - in the above video as well as in many other articles, videos, and graphs all over my company's web site.

--Ethan

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Ethan's Audio Expert book

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post #5681 of 10422 Old 01-16-2010, 09:41 AM
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Quote:
Originally Posted by pepar View Post

many use the 17" face chunk design, and some have the luxury (of space) to use the 24' face.

34 inches rules!

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post #5682 of 10422 Old 01-16-2010, 12:11 PM
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Quote:
Originally Posted by Ethan Winer View Post

34 inches rules!

is this 34" deep, or, 34" across the front of the corner(i.e. the hypotenuse)
i currently am 17" deep X 34" front X eight feet, floot to ceiling, GOM faced.
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post #5683 of 10422 Old 01-16-2010, 02:14 PM
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Quote:
Originally Posted by Ethan Winer View Post

Yes, all rooms need plenty of bass trapping.



4 inches of rigid fiberglass. Even more at the bottom if possible, straddling the wall-floor corner fully from left to right.

--Ethan

when you say 'more', how much? and, related, is this a product your company mfgs?
you may pm me if you choose not to respond in this thread.
thx
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post #5684 of 10422 Old 01-16-2010, 02:16 PM
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new question.
we all cover the f/g with GOM. is there any knowledge/statistics about covering the rigid f/g with plastic screening? (as in 'screen door' screening.)
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post #5685 of 10422 Old 01-16-2010, 10:21 PM
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Quote:
Originally Posted by Ethan Winer View Post

Not in this universe. My company's video Hearing is Believing shows a huge before/after change with a lot of bass traps, and in this case the traps aren't even straddling corners. Floyd is correct in theory, but in practice you don't have to put panels several feet out from the wall to make a huge improvement. The video above shows a very large improvement in the response and ringing to 40 Hz and below.



Again, he is wrong - and easily proven wrong - in the above video as well as in many other articles, videos, and graphs all over my company's web site.

--Ethan


And to second what you're saying, Ethan, all anyone has to do to actually "see" the difference that can be obtained with corner mounted bass traps is to download REW and measure the in-room response before and after. This is important for people to do anyway, since everyone's room is different and very few match the models exactly. If you put your absorption in the right place (and in the right amounts), the difference, both measured and audible, is *not* subtle.
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post #5686 of 10422 Old 01-17-2010, 09:58 AM
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In this scenario, do I need corner bass traps beside the screen wall in the main room AND behind the screen, where I currently show the 2" of 703? The cross-hatched patterns indicate the bass traps and the 2" of 703 up against the wall.

I'm hoping to put the sub, mains and ctr behind an AT screen. One concern I have is with imaging. If the mains go behind the screen, they will only be 6' apart at the most. Front row viewing will be from 9 1/2'. Will the mains be too close together? Moving them to the sides gets problematic because they would need to sit in front of the duct, but I don't want to move the screen any further into the room. I'm hoping behind the screen is ok.
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post #5687 of 10422 Old 01-17-2010, 10:30 AM
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Quote:
Originally Posted by yacht422 View Post

is this 34" deep, or, 34" across the front of the corner(i.e. the hypotenuse)

That was half meant as a joke, because my company recently started offering a filled corner trap that's 34 inches wide across the front face.

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post #5688 of 10422 Old 01-17-2010, 10:31 AM
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Quote:
Originally Posted by gremmy View Post

all anyone has to do to actually "see" the difference that can be obtained with corner mounted bass traps is to download REW and measure the in-room response before and after. This is important for people to do anyway

Yes and Yes.

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post #5689 of 10422 Old 01-17-2010, 10:33 AM
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Quote:
Originally Posted by Spaceman View Post

In this scenario, do I need corner bass traps beside the screen wall in the main room AND behind the screen wall in the recessed cavity?

IMO, in every scenario you want as much bass trapping as possible.

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post #5690 of 10422 Old 01-17-2010, 02:00 PM
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so, my present arrangement is ok, i presume.
( i also have two 2'X4'X4" 701 panels on the rear wall, each on either side of a double wide window that i have "faced" with a 4" X 4' X 6' panel.)
you had mentioned bass trapping at the front wall, floor to wall, 4" min. thick.
Do you offer this , and is 6" better than 4"?(or, is this another diy project that will yield acceptable results)
(i am running two subs, and a pair of full range spkrs, front firing, ported 360 deg. at the bottom. (REVEL Ultima Salons)
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post #5691 of 10422 Old 01-17-2010, 02:09 PM
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Quote:
Originally Posted by Spaceman View Post



In this scenario, do I need corner bass traps beside the screen wall in the main room AND behind the screen, where I currently show the 2" of 703? The cross-hatched patterns indicate the bass traps and the 2" of 703 up against the wall.

Quote:


I'm hoping to put the sub, mains and ctr behind an AT screen. One concern I have is with imaging. If the mains go behind the screen, they will only be 6' apart at the most. Front row viewing will be from 9 1/2'. Will the mains be too close together? Moving them to the sides gets problematic because they would need to sit in front of the duct, but I don't want to move the screen any further into the room. I'm hoping behind the screen is ok

.

toole et al. recommend mains be as far apart as is the distance to the listener.(8 feet apart =8 feet to the listener.) a narrower mains measurement will reduce the sound stage, but, then, speakers behind the screen will cost sonic value as well. your choice.
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post #5692 of 10422 Old 01-18-2010, 09:18 AM
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My head is spinning and my theater is a-waiting....
http://www.avsforum.com/avs-vb/images/smilies/eek.gif
I was all set to completely cover my front wall (18' x 9') with 2" DIY Rockwool panels. I changed course based on some threads saying that 2" was too much absorption, so instead, in each corner, I hung 2' x 8' 4" thick panels and bought enough 1" 703 to do the center 14'. The 703 will be framed on 1/4" 4x8 luan sheets.

Now I read (at about post 175) that 3"-4" is the cats meow for the front wall. Too late! Panels built. So I'm wondering if my luan backed 1" panels were hung on furring strips giving me 2" gap from the wall, would the 703 faced luan act as a diaphamic basstrap, if so, how much, or would it even be worth bothering with?

Any feedback?
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post #5693 of 10422 Old 01-18-2010, 03:06 PM
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Now I read (at about post 175) that 3"-4" is the cats meow for the front wall. Too late! Panels built. So I'm wondering if my luan backed 1" panels were hung on furring strips giving me 2" gap from the wall, would the 703 faced luan act as a diaphamic basstrap, if so, how much, or would it even be worth bothering with?

Any feedback?

Well...at some frequency it probably does. There's no way to know unless you test it. 1" 703 is fine for the front wall though...3"-4" is great if the room is small and you need more low frequency absorption, but I think you'll be alright the way you are. How does it sound? Have you had a chance to give the room a test run?

Frank

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post #5694 of 10422 Old 01-19-2010, 12:44 PM
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the equal lateral triangle is always best for stereo imaging. Optimum timbre and imaging is obtained when you point (toe-in) the speakers towards the listening position. Also pulling them away from the wall will open up the sound, increase spaciousness and improve imaging. I have mine 4' off the screen wall with a 15 degree toe-in angle. Just open them up the best you can.
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post #5695 of 10422 Old 01-19-2010, 04:26 PM
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I am thinking about putting some of the panels with art prints in my room. They would go behind my listening position. The listening seats are pretty close to the rear wall, about 2-3 feet. The ASC panels claim to have diffusion strips, which they say are ideal for this sort of location. Something about the sound being too "dead" if you are too close to a panel that is straight absorbing. Would this really be advantageous as compared to other panels?
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post #5696 of 10422 Old 01-20-2010, 03:24 PM
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Quote:
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I am thinking about putting some of the panels with art prints in my room. They would go behind my listening position. The listening seats are pretty close to the rear wall, about 2-3 feet. The ASC panels claim to have diffusion strips, which they say are ideal for this sort of location. Something about the sound being too "dead" if you are too close to a panel that is straight absorbing. Would this really be advantageous as compared to other panels?

No, it's not. The closer you are to the back wall, the more absorption becomes necessary to deal with the strong reflections.

Frank

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post #5697 of 10422 Old 01-20-2010, 06:27 PM
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OK, since good advice is being dished out here I thought I would jump in. I am new to the home theater world. We are in the construction phase of our addition that will be a home theater. The room is basically 18' x 14' with a 9' ceiling. In the room there is also a 2' x 6' insert for the computer area. So the room is not perfectly rectangular. It would have been 18' x 16' but it is behind our living room fireplace so it goes into this room which is an addition. We are going with spray foam insulation for energy efficiency. The walls and ceiling will be sheetrock and the flooring will be engineered hardwood. My audio will be KEF HTS5005.2 with a set of Proficeint Audio in ceiling speakers for the rear channels. I am told I need to add some acoustical panels into the room. I am kind of confused about the placement. I was going to build columns to house them because I want the room to have a clean look and not have panels hanging on the walls everywhere. Do these things need to be directly across from the speakers? Any advise would be greatly appreciated. Tomorrow I will scan in the floor plan and post it here.

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post #5698 of 10422 Old 01-21-2010, 12:21 AM
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I'm planning to install some diffusors on the rear side walls of the room, just wondering if the layout of the diffusors needs to be symmetrical on both side walls?

Can I install say 3 pieces of 2' x 2' diffusors on the left side wall and 1 piece on the right side wall? This is due to an existing cabinet obstructing some parts of the rear right side wall.
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post #5699 of 10422 Old 01-21-2010, 12:10 PM
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^^^ Yes, symmetry is important. But the side walls toward the back of the room are not the first place I'd put diffusors. The rear wall makes more sense.

--Ethan

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post #5700 of 10422 Old 01-21-2010, 12:55 PM
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Ethan:
so then the conclusion is that the rear wall is a good place for diffusion, but diffusors lose efficacy if your listening position is too close to the rear wall?
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