Acoustical Treatments Master Thread - Page 365 - AVS Forum | Home Theater Discussions And Reviews
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post #10921 of 10946 Old 07-02-2015, 05:24 PM
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As far as controlling sound, rattles, and vibration, has anyone encountered their screen rattling at times? I find myself constantly making adjustments and shoving foam between the screen and the metal track trying to find a way to resolve it. Doesn't happen often, but when I hear it rattle, it's very annoying. I appreciate any suggestions from folks who may have had a similar problem.

I have a 110" Fixed DragonFly Screen
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post #10922 of 10946 Old 07-13-2015, 07:57 AM
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New theater

Hi all, first post in this fantastic and loong thread.
I am Marco, I am from Italy, and I have a sickness for audio video etc etc.
Most of my friends knows it and always came and ask.
Last one want to build a theater in his bunker, yes a concrete bunker.
I've been trying to learn as much as possible.
I wanted to build a theater 5m by 7m, height is variable, 2,1m in the first part, then 2,9m. Planning to make 9.2.6, is it possible?
6 would be 2 ceiling mounted and 4 reflecting, what would you use as a material where you expect the reflection of the atmos module?
Then I have tousand more of question but I think it is enough as a start.
Marco.
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post #10923 of 10946 Old 07-13-2015, 10:23 PM
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I'm back. Been busy selling my old speakers and getting the M&K 150's set up. I'm leaning heavily on placing a thick insulation like an R30 and place around the perimeter of the room on top of the ceiling tiles, though again, I hate getting into the tiles. Still would be less work than lining the entire ceiling with it. Is R30 thick enough? It appears like it would be. I've taken care of my high frequency problem with Acoustic blankets, so I don't really want more high frequency absorbsion. I believe having the ceiling tiles as a barrier would prevent highs from becoming further attenuated.

I put a drawn out image of my room about a page back. It's 10 x21x8 to drop ceiling. I'm thinking I'd get similar response to soffit mounting by placing the thick fiberglass on top of the perimeter tiles, plus the traps would be out of the way of the floor. It seems like a good first start. As I mentioned before, I have real trouble doing floor to ceiling traps in corners due to my layout.

It's not that I'm noticing bad sound, it's just a warmer sound because the highs no longer have room gain and echoes. My two subs help regulate peaks and nulls and are not on the boomy side, though the Boston Acoustics 12" is not in the same caliber as my SVS sub I use up front. My main goal I guess is to shorten time durations after signals leave the subwoofer so that they become more distinct and don't bleed over other sounds.

Is my solution sound? (no pun intended.) I figure I can supplement with some limp membrane traps if needed as they can go up against the wall.
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post #10924 of 10946 Old 07-16-2015, 07:40 PM
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Nice
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post #10925 of 10946 Old 07-17-2015, 08:45 AM
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So, I'm off to buy the fiberglass for perimeter placement above my ceiling tiles. I have a choice of R38 16 inches wide or R30 24" wide. Which would be better?
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post #10926 of 10946 Old 07-18-2015, 01:08 AM
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Can I just clarify something?

Is it correct that ordinary fibreglass rolls are better for Superchunk traps than rigid Rockwool slabs?

It's a lot cheaper if so. I thought denser Rockwool would be better?

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post #10927 of 10946 Old 07-18-2015, 07:43 AM
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The story is that when thicker than 6", lower gas flow resistivity material is more effective at low frequencies. So, yes: loose fiberglass batts will be more effective bass traps than something like 6pcf fiberboard will be.
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post #10928 of 10946 Old 07-19-2015, 11:31 PM
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Originally Posted by HopefulFred View Post
The story is that when thicker than 6", lower gas flow resistivity material is more effective at low frequencies. So, yes: loose fiberglass batts will be more effective bass traps than something like 6pcf fiberboard will be.
That's a pleasant surprise. I have some Rockwool left over, but I'll get another use for it.

I'll buy two rolls of fibreglass today.

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post #10929 of 10946 Old 07-21-2015, 09:21 AM
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I understand the need for absorption, diffusion as well as bass traps but since I have crossed over to atmos my thinking is somewhat fussy now. With this new format the front three speakers don't seem to be much more driven than the balance, well not quite as much as they were before. I'm planning on adding some panels but now I'm somewhat waiting to see what the experts think about placement. Should I set absorption panels at the front three speaker 1st reflections points as previously recommended? Can someone weigh in on this topic, please?
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post #10930 of 10946 Old 07-21-2015, 10:53 AM
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I'm ::so:: not an expert, but I would think ideally you would want to to absorb first reflections from all channels. With Atmos that can be anywhere from 9 to 13 channels. That's one reason I decided to treat my entire room above ear level.

If you can't do this, then I believe the frontstage is still the most important to treat. Remember that first reflections hit the ceiling and floor as well as the side walls, and there can be some scatter if your room is narrow (like mine is.)

Why not start with treating the first reflections from your frontstage and see how you like the results. If you like them, then you can add more treatment later.
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post #10931 of 10946 Old 07-21-2015, 09:04 PM
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Can someone tell me if a riser made as a bass trap would negate having to install corner traps as well? Sealed room.

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post #10932 of 10946 Old 07-21-2015, 09:10 PM
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Well there's not really any information you've posted on your room so it's hard to say...
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post #10933 of 10946 Old 07-22-2015, 04:31 AM
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Quote:
Originally Posted by asoofi1 View Post
Can someone tell me if a riser made as a bass trap would negate having to install corner traps as well? Sealed room.
Depends on the riser you build and the room problems you want to fix
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post #10934 of 10946 Unread 07-28-2015, 04:58 PM
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I'm too lazy to look up rules on posting prices and sites so i will stay vague.

If anyone is looking for 2" Auralex wedge 2'x4' panels, there is a sale at massdrop ending soon that saves almost $300 from the current amazon price.

i have been looking for a discount on treatment panels for a long time, and this seems to be a rare one. just thought i'd share. hopefully it doesnt get me in trouble with the mods.

Beauty, thy name is KURO.
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post #10935 of 10946 Unread 07-28-2015, 05:41 PM
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Originally Posted by bflip1080 View Post
I'm too lazy to look up rules on posting prices and sites so i will stay vague.

If anyone is looking for 2" Auralex wedge 2'x4' panels, there is a sale at massdrop ending soon that saves almost $300 from the current amazon price.

i have been looking for a discount on treatment panels for a long time, and this seems to be a rare one. just thought i'd share. hopefully it doesnt get me in trouble with the mods.
Stupid question, but what's the best way to use these? I'm planning on 2" insulation triangles stacked in the corners for bass traps. And 2' x 4' x 2" covered insulation at the first reflection points. Where would I use these panels?

Last edited by yngdiego; 07-28-2015 at 05:56 PM.
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post #10936 of 10946 Unread 07-28-2015, 06:58 PM
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Stupid question, but what's the best way to use these? I'm planning on 2" insulation triangles stacked in the corners for bass traps. And 2' x 4' x 2" covered insulation at the first reflection points. Where would I use these panels?

good info here in this vid.

you could use these instead of the covered insulation at thefirst(or mirror) reflection points or behind the speakers for early reflections.

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post #10937 of 10946 Unread 07-29-2015, 08:53 AM
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So, I'm pretty far from theater completion, but is it a good idea to buy into that drop?

It seems like most people just use some sort of insulation covered with fabric for absorption. Then besides that, they use diffusion of some kind to treat in other ways.

My theater will be something like 14'x22'8', so I'm trying to determine if it's good to just get a set.

I haven't gotten far enough in my build to really research the sound treatment aspect yet, so I'm really out of my depth here.
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post #10938 of 10946 Unread 07-29-2015, 01:13 PM
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Quote:
Originally Posted by sigma722 View Post
So, I'm pretty far from theater completion, but is it a good idea to buy into that drop?

It seems like most people just use some sort of insulation covered with fabric for absorption. Then besides that, they use diffusion of some kind to treat in other ways.

My theater will be something like 14'x22'8', so I'm trying to determine if it's good to just get a set.

I haven't gotten far enough in my build to really research the sound treatment aspect yet, so I'm really out of my depth here.
I've tried acoustic foam and although it has it's uses (I'll be putting foam corner bass absorber back into the horizontal corners of my freshly updated theater) I prefer insulation filled panels.

Why insulation filled panels:
  1. It's easier to fill a couple small holes with Spackle and repaint than it is to clean off glue then repaint. Glue is not that easy to clean off.
  2. Panels are more efficient, yes they're more expensive but if you consider NRC figures between the two the cost ends up being about the same for the NRC values.
  3. I've found hanging panels more fool proof and easier than gluing foam. I've had glue failures but have not had panel mount failures. Hanging panels is as easy as hanging a picture frame. My glue failures were due to the unevenness of the walls in my 50YO house, if your walls are more even than mine you would have better luck with glue than I did.
  4. NRC shaping. Different materials have different NRC graph shapes. Use the material that works best for the frequencies that need tamed.
Why Acoustic Foam:
  1. Cost effective if you can put up with the glue and don't need additional absorption power.
  2. NRC shaping. Different materials have different NRC graph shapes. Use the material that works best for the frequencies that need tamed. I'm using the foam bass absorbers because of their even response down through the low frequencies, fiber glass and rock wool bass panels tend to have peaks and I needed something more even. But I'm not gluing them again. After using fiberglass filled bass panels in vertical corners and the back wall I had a pretty even room response so the foam fit the spec.
Auralux ships uncompressed, probably because it's made, warehoused and then shipped. It makes it expensive to ship because of it's bulk.


I got my foam bass absorbers from The Foam Factory,http://www.thefoamfactory.com/acoust...usticfoam.html


It takes a week or two for them to ship because they're made to order but they ship vacuum compressed so shipping is ultra inexpensive and a lot safer, they shipped my order of 10 24" x 12" bass absorbers wrapped in 3 layers of cardboard, it was shaped like a 19" around football when it arrived, the first layer of cardboard was cut through in places due to abusive handling but the product was completely safe. The foam must be un-packaged and allowed to expand as soon as possible, it can take 12 to 48 hours for it to expand. It can not be stored in it's compressed shape!! Make sure you have time for the order to come and space for the foam to decompress and be careful not to cut the foam when you unwrap the stuff.



Cheers,
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post #10939 of 10946 Unread 07-29-2015, 03:14 PM
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OK, this seems straightforward from searching AVS and studying theater wall treatment...<br><br>
FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling.<br>
CEILING: No acoustical treatment - none, nada.<br>
FLOOR: Thick, plush carpet is fine.<br><br>
But here's where it gets confusing, and I need help...<br><br>
SIDEWALLS<br>
A) Acoustical treatment (1" Insul-Shield) from floor to ear-height (44"), with 16oz polyester batting above.<br>
--or--<br>
B) Acoustical treatment (1" Insul-Shield) from floor-to-ceiling on all 1st reflective surfaces.<br><br>
These 2 theories seem to contradict each other. So which is it?<br><br><br>
BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:<br><br>
Owens Corning Select Sound Black Acoustic Board<br>
Owens Corning Fiberglas 703 Series duct insulation.<br>
Johns Manville Insul-Shield<br>
Johns Manville Linacoustic Permacoate rolls.<br>
Certainteed Certpro Acoustaboard Black<br>
Knauf Duct board EI-475<br>
Knauf Duct liner EM<br><br>
...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.
make!come to here again thks!
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post #10940 of 10946 Unread Today, 09:42 AM
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I need some advise from those who have experience with poor rooms and treatments. I have probably the worst room as far as acoustics are concerned, but I want to improve it as much as possible. Here is the room as it currently sits. The dimensions are 20' wide x 30' deep. Walls go up 40" and then slant toward the ceiling. The flat part of the ceiling in the middle where the fans are is 8' wide. The slanted ceiling is 8 feet 7" from half wall to ceiling. A 120"AT screen will be in front of the center channel and subs. All of the white i.e. baseboards and vents will be painted brown prior to the projector and the fans will be replaced with black units with the front two not having light assemblies.



On the side walls, I have these Marvel murals that I want to keep. I am a big Marvel fan and these are staying (I know I am a nerd and have accepted it). Murals are 118"x30".



I have purchased 703 2'x4' panels and am ready to to start building the frames and mounting them. I have a couple of ideas and wanted to see which of the two (in any) are a good idea.

First, is to keep the murals as they are and put panels treating the top ceiling/wall angle and then placing panels under the murals in a vertical position. A full 4' 703 panel will fit below the mural posters.



The other idea is to put build panels that will go under the posters and then move the posters to be centered on the angled wall. I think this may work better since the posters may keep the room lively by providing some reflection of the high frequencies.


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post #10941 of 10946 Unread Today, 09:51 AM
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For your posters, you could have them reprinted on fabric and then be acoustical panels...

DIY Custom-Printed Movie Poster Acoustic Panels - cheap!

The early users of this printing service have fairly washed out images, the print and color quality is excellent now.
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post #10942 of 10946 Unread Today, 10:19 AM
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Originally Posted by nickbuol View Post
For your posters, you could have them reprinted on fabric and then be acoustical panels...

DIY Custom-Printed Movie Poster Acoustic Panels - cheap!

The early users of this printing service have fairly washed out images, the print and color quality is excellent now.
I just emailed them to see if they can scan something that large. The posters are 118"x30"

Thanks for the suggestion.
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post #10943 of 10946 Unread Today, 03:06 PM
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I need some advise from those who have experience with poor rooms and treatments.
Generally it's best to treat first and second reflection points and vertical corners with bass traps first. That being said...

First.
Your horns are a great help as far as first and second reflection points. How is your stereo imaging? Have you heard a good stereo setup with good imaging? If you're happy with your stereo imaging I'd skip first and second reflection treatment (you might not have any with those horns, except for your center channel). The first go around I'd just treat corners with bass traps.*(If not see below) Build 4 inch thick panels and treat your vertical and diagonal corners as best you can. Then I'd test to see what offending frequencies are present. My guess would be that you still have bass issues but you need to find out what frequencies they're at, if they're around 80Hz to 125Hz or so I'd move the 4 inch panels to horizontal corners where they intersect diagonal corners and put in some 6" vertical bass absorbers. Measure again. Still have bass issues? Build some more bass absorbers to treat the proper frequencies and put them on the back wall. For your proposed horizontal corner absorbers I'd make 4 inch, I think it's more important to treat vertical corners and corner intersections first though.

Second.
Does your center channel have "imaging" or first reflection issues? Check with a mirror. Get a cheep full height, made of flexible metal mirror and check your center channel reflection points at your MLP. It could very well be behind the MLP and not an issue.

Third.
If your stereo pair doesn't have first or second reflection point issues because of the horns then...break of modes. Your testing should have shown frequency issues in the higher ranges. You don't need symmetrical or full coverage to treat modes you just need to break them up. You can alternate left/right coverage with gaps. I really like the printed fabric poster idea!!! You can use 1 inch or 2 inch depending on the frequencies you need to treat, 1 inch are good to about 600Hz, 2 inch is good to about 350Hz.

*
First and second reflection points. If you do have issues in this regard try angling your speakers to eliminate them. If they persist then use an unbreakable mirror to find first and second reflection points and treat them, including the ceiling and diagonal walls.

Cheers,
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Quote:
Originally Posted by dnoonie View Post
Generally it's best to treat first and second reflection points and vertical corners first. That being said...

First.
Your horns are a great help as far as first and second reflection points. How is your stereo imaging? Have you heard a good stereo setup with good imaging? If you're happy with your stereo imaging I'd skip first and second reflection treatment (you might not have any with those horns, except for your center channel) the first go around and just treat corners with bass traps.*(If not see below) Build 4 inch thick panels and treat your vertical and diagonal corners as best you can. Then I'd test to see what offending frequencies are present. My guess would be that you still have bass issues but you need to find out what frequencies they're at, if they're around 80Hz to 125Hz or so I'd move the 4 inch panels to horizontal corners where they intersect diagonal corners and put in some 6" vertical bass absorbers. Measure again. Still have bass issues? Build some more bass absorbers to treat the proper frequencies and put them on the back wall. For your proposed horizontal corner absorbers I'd make 4 inch, I think it's more important to treat vertical corners and corner intersections first though.

Second.
Does your center channel have "imaging" or first reflection issues? Check with a mirror. Get a cheep full height, made of flexible metal mirror and check your center channel reflection points at your MLP. It could very well be behind the MLP and not an issue.

Third.
If your stereo pair doesn't have first or second reflection point issues because of the horns then...break of modes. Your testing should have shown frequency issues in the higher ranges. You don't need symmetrical or full coverage to treat modes you just need to break them up. You can alternate left/right coverage with gaps. I really like the printed fabric poster idea!!! You can use 1 inch or 2 inch depending on the frequencies you need to treat, 1 inch are good to about 600Hz, 2 inch is good to about 350Hz.

*
First and second reflection points. If you do have issues in this regard try angling your speakers to eliminate them. If they persist then use an unbreakable mirror to find first and second reflection points and treat them, including the ceiling and diagonal walls.

Cheers,
Thanks for the detailed response. Previously, I only had two JBL4722's upfront with a TV in the middle. The imaging was fine, and I was running without any EQ. My receiver has Audyssey but I felt it really nurtured the JBLs, so I didnt use it. I have since sold the TV and decided to go projector and have bought the center 4722. My rear speakers are the same as the front three so I have horns all the way around in a 5.2 setup. I also bought Dirac Live (miniDSP DDRC-88a) for EQ and a dual core anti-mode for the subs. I am sure between the two it will clean things up nicely but I would like to treat the room first and then use the digital effects to smooth out the bumps in the road. The horns do focus the sound nicely and even without EQ or treatments the room didnt sound bad, but I also have never really heard a properly treated room so it may sound like crap and I am just ignorant to what proper sound is like. I will have to see if I can find some youtube vids on using a mirror to find reflection points.

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post #10945 of 10946 Unread Today, 03:57 PM
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Originally Posted by Molon_Labe View Post
Thanks for the detailed response. Previously, I only had two JBL4722's upfront with a TV in the middle. The imaging was fine, and I was running without any EQ. My receiver has Audyssey but I felt it really nurtured the JBLs, so I didnt use it. I have since sold the TV and decided to go projector and have bought the center 4722. My rear speakers are the same as the front three so I have horns all the way around in a 5.2 setup. I also bought Dirac Live (miniDSP DDRC-88a) for EQ and a dual core anti-mode for the subs. I am sure between the two it will clean things up nicely but I would like to treat the room first and then use the digital effects to smooth out the bumps in the road. The horn do focus the sound nicely and even without EQ or treatments the room didnt sound bad, but I know it can be better. Pardon my ignorance, but how do I use a full size mirror to find the reelection points?
Nice that the horns are effective!!

For using a mirror to find reflection points check this video about 2:10 in,
. Watch the whole video if you'd like, it's pretty good.
Keep in mind that this technique does not consider the use of your horn arrangement. That horn is 90 degree, so if it's angled 45 degrees or a bit more from the wall then there shouldn't be an issue. If you think you might have an issue, experiment with speaker angle, speaker placement and or listening position to see if the sound can be improved. You might find a more ideal position but it might not work for other reasons, like screen placement, but at least you know the sound can be improved and treatment will likely help. If you think you can improve the sound with some absorbers then try some treatment there, you can always move treatment to a location where you can use it to break up modes if it doesn't make a difference, assuming you haven't built too many panels.

Cheers,
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wse
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Originally Posted by dnoonie View Post
Nice that the horns are effective!!

For using a mirror to find reflection points check this video about 2:10 in, https://www.youtube.com/watch?v=B9u7k2V4YPw. Watch the whole video if you'd like, it's pretty good.
Keep in mind that this technique does not consider the use of your horn arrangement. That horn is 90 degree, so if it's angled 45 degrees or a bit more from the wall then there shouldn't be an issue. If you think you might have an issue, experiment with speaker angle, speaker placement and or listening position to see if the sound can be improved. You might find a more ideal position but it might not work for other reasons, like screen placement, but at least you know the sound can be improved and treatment will likely help. If you think you can improve the sound with some absorbers then try some treatment there, you can always move treatment to a location where you can use it to break up modes if it doesn't make a difference, assuming you haven't built too many panels.

Cheers,
Many always forget the ceiling!
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