Acoustical Treatments Master Thread - Page 363 - AVS | Home Theater Discussions And Reviews
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post #10861 of 10877 Old Yesterday, 04:34 PM
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Originally Posted by Airbornesfc View Post
Anyone put fake stone along the lower 1/3 of your side walls? Thinking of doing this but know it's not the best to use.
I have real stone on the bottom quarter of my room along with hard floors. Abrsorptive rugs and furniture are a must in that setting.
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post #10862 of 10877 Old Yesterday, 09:16 PM
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nb67,

Yes, generally absorbers at first reflection points are a good thing. Your absorbers may be acting like an EQ, however. If you've absorbed all your highs but not affected the reverb time of your mids and lows then I could totally see how that would sound dead. What kind of absorbers are you using, where did you place them, and how big are they? And how big is your room?
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post #10863 of 10877 Old Yesterday, 09:19 PM
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Airbornesfc,

As long as the fake stone is below ear level, I don't think you'll have a problem. It would behave like a mass loaded bare wall, I think. Maybe with a little diffusion at high frequencies too.
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post #10864 of 10877 Old Today, 07:43 AM
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Quote:
Originally Posted by Jonathan DA View Post
nb67,

Yes, generally absorbers at first reflection points are a good thing. Your absorbers may be acting like an EQ, however. If you've absorbed all your highs but not affected the reverb time of your mids and lows then I could totally see how that would sound dead. What kind of absorbers are you using, where did you place them, and how big are they? And how big is your room?
The room is 12'x18', so fairly small. I used http://www.acoustimac.com/acoustic-p...oustic-panels/. In the diagram the red are roof to floor bass traps (24x48x6), except the one off below screen. Orange are acoustic panels, 24x48x2. Yellow panels are on the roof slope and are 24x24x2.
Black are speakers (5.4 system), rear is 2 x subs stacked behind sofa and blue is sofa, green is screen.
System is using Audyssey xt32, and dspeaker dual core for eq, although for 2 channel audio I prefer to run without eq or subs.
I'd say about 70% of the time I'm watching movies but 30% enjoy kicking back with beer and enjoy some 2 channel audio. So trying to get the best out of HT and 2 channel audio. I know that there are fundamental differences but I'm trying to find the happy medium.
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post #10865 of 10877 Old Today, 08:20 AM
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Originally Posted by Jonathan DA View Post
Its Chris,

What is behind the large panels surrounding the screen? Empty air? I would think you could fill the space behind the screen along with removing those panels and fill those spaces too with a membrane trap covered by a porous absorber. That would eat into your decay times across the spectrum.

Also, if you're coming from the REW thread, do you have measurements of your current room?
Hi Jonathan,
In the unpainted image, the white column on the right is the chimney breast. I put in a false wall then to even that end of the room so I could place the screen on it. The wall is just MDF and nothing (empty) in behind the screen. If I was doing this again I would have my equipment at the back of the room. But it would be quite a lot of hassle to start moving all this round! It would cost me around €300 to fill behind the screen with the rolls of rockwool. I had figured if I made a few panels from RW3 and placed then in the opening of the wall behind the screen, and then put panels above and below the screen (obviously these wouldnt be the same thickness as the ones behind the screen). I could also pack the top shelves with some RW3 panels cut and leave one or two for equipment. But I know that the shelves and the ones with equipment will still cause issues.

REW : Link (Smoothed the sub tests by mistake - so need to be unsmoothed)
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post #10866 of 10877 Old Today, 08:33 AM
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nb67,

First, let me caveat this by saying I'm just amateur whose read a lot and done some experimenting. If one of the pros chimes in with differing advice - follow their recos over mine. That said, your room doesn't look too dead to me. A few thoughts:
  1. I assume you re-ran your Audyssey calibration routine after the treatments were installed. If not, that's step 1.
  2. I'm also guessing that during movies, the sound is good, but it's during two channel listening that you feel it's too dead, correct?
  3. There is a chance you're just used to a live room and prefer it. If that's the case, you just need to remove some treatments. Or give yourself time to adjust to the sound.
  4. If #3 isn't true, then you may have over deadened the room because of some unique property of it (vaulted ceilings, wall construction, etc.). Let's assume that's true for now.
  5. If you're handy with computers, I'd suggest getting REW and measuring your room. That will help pinpoint the problem areas, but there's also a steep learning curve.
  6. If you don't want to mess with REW, you might try experimenting with your back wall first. Try removing the rear absorbers all together. Then try putting them back and covering them in kraft paper. Then do the same thing with the side wall treatments. Floyd Toole (famous acoustics guy and speaker designer) actually suggests that side wall reflections can be a good thing.
  7. What speakers are you using? You may have some unusual off axis response that when combined with the less-than-full spectrum absorption on the side walls is causing some odd frequency response in the reflected sound that reaches your ears. In which case you might want some diffusion in combination with the absorbers at the first reflection points instead of pure absorption.
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post #10867 of 10877 Old Today, 08:43 AM
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Doing some testing here. If you play a 38.5hz tone, either side of the room seems loud, middle is fine. Front two corners seem to be higher but back corners not as much, maybe the slanted ceiling also has an effect?
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post #10868 of 10877 Old Today, 08:49 AM
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Its Chris,
How deep are those shelves in the corners? Are they deep enough that could spare 4-6" of depth at the back of them? If so, you could build VPR bass traps into them and then just put your equipment in front of them. Or buy them. Like the RPG Modex panel.

I think I'd also take down the MDF and use all that space plus the space behind the screen to build a compound trap. A porous layer with a plastic membrane behind it, then as much thickness of fiberglass as you can put behind the membrane.


Also, I'd check into which room dimension is causing that 178Hz peak in your measurements. If that's a width related mode, then you probably need something on the side walls to kill that.
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post #10869 of 10877 Old Today, 09:06 AM
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Quote:
Originally Posted by Jonathan DA View Post
Its Chris,
How deep are those shelves in the corners? Are they deep enough that could spare 4-6" of depth at the back of them? If so, you could build VPR bass traps into them and then just put your equipment in front of them. Or buy them. Like the RPG Modex panel.

I think I'd also take down the MDF and use all that space plus the space behind the screen to build a compound trap. A porous layer with a plastic membrane behind it, then as much thickness of fiberglass as you can put behind the membrane.


Also, I'd check into which room dimension is causing that 178Hz peak in your measurements. If that's a width related mode, then you probably need something on the side walls to kill that.
Yeah removing the MDF probably would be better, alot of work though! Then need to still sort it so that it blends, fills space left by MDF and the screen still hangs securely. Shelves are 45cm deep. I could fill all of them apart from two each side. This started out as a simple play around with REW after I was planning on buying new rear speakers to upgrade to 7.1. I've since bought the UMIK mic, and looking at hundreds to sort the sound.... Ignorance is bliss sometimes! (but always knew there were issues) How do you check which room dimension is the cause?
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post #10870 of 10877 Old Today, 09:18 AM
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Welcome to the club My room (when it's finally finished) will, by far, be the most expensive piece of equipment in my system.

To check the room dimensions, you can figure out how long a 180Hz wave is (you can find calculators via Google) and then see if a multiple of that wavelength matches a dimension of your room. You can also go into the room sim in REW and model your room. It will predict where the modes are for you. It will be off in your case, though, because you have a vaulted ceiling, but it might give you a good idea of where to start looking.

It's also possible (probable even) that the 180Hzish problem is SBIR.
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post #10871 of 10877 Old Today, 09:43 AM
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Quote:
Originally Posted by Jonathan DA View Post
Welcome to the club My room (when it's finally finished) will, by far, be the most expensive piece of equipment in my system.

To check the room dimensions, you can figure out how long a 180Hz wave is (you can find calculators via Google) and then see if a multiple of that wavelength matches a dimension of your room. You can also go into the room sim in REW and model your room. It will predict where the modes are for you. It will be off in your case, though, because you have a vaulted ceiling, but it might give you a good idea of where to start looking.

It's also possible (probable even) that the 180Hzish problem is SBIR.
Ha, I can see how that happens! Its a hard thing to justify spending money on to the other half!! Even though she gives out about the sound being too loud at times, then turns it down only to turn it up after actions sequences are finished I've attached an image of the front wall before the MDF panels went on. Have one of the excel sheets with the calculator here. Will check it out. Cheers.
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post #10872 of 10877 Old Today, 10:54 AM
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Quote:
Originally Posted by Jonathan DA View Post
To check the room dimensions, you can figure out how long a 180Hz wave is (you can find calculators via Google) and then see if a multiple of that wavelength matches a dimension of your room.
http://www.bobgolds.com/Mode/RoomModes.htm
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post #10873 of 10877 Old Today, 11:00 AM
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Even though she gives out about the sound being too loud at times, then turns it down only to turn it up after actions sequences are finished
That's why soundproofing is important. If the noise floor of the room is low enough, you can keep the volume down and constant throughout the movie. With a low noise floor, there's less masking noise making the talking portions inaudible, and when the action sequences start its not painfully loud.

I wonder if there's a receiver with a max volume (dB(C)) limiter. So that quiet scenes are still quiet, talking scenes are easily audible (near the set max volume), but you don't scare the neighbours at the action sequences because the limit lowers the volume knob temporarily (or when you walk to the kitchen during a commercial that gets horribly loud when you're too far from the remote to shut it down)

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post #10874 of 10877 Old Today, 11:08 AM
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I'm thinking about taking the jump and doing my first set if treatments. While I'm currently thinking about bass traps and points of first reflection, my question is how to deal with my side surrounds being bipoles? W would I want to leave the front and back wall untreated in that case?

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post #10875 of 10877 Unread Today, 12:33 PM
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Quote:
Originally Posted by Jonathan DA View Post
nb67,

First, let me caveat this by saying I'm just amateur whose read a lot and done some experimenting. If one of the pros chimes in with differing advice - follow their recos over mine. That said, your room doesn't look too dead to me. A few thoughts:
  1. I assume you re-ran your Audyssey calibration routine after the treatments were installed. If not, that's step 1.
  2. I'm also guessing that during movies, the sound is good, but it's during two channel listening that you feel it's too dead, correct?
  3. There is a chance you're just used to a live room and prefer it. If that's the case, you just need to remove some treatments. Or give yourself time to adjust to the sound.
  4. If #3 isn't true, then you may have over deadened the room because of some unique property of it (vaulted ceilings, wall construction, etc.). Let's assume that's true for now.
  5. If you're handy with computers, I'd suggest getting REW and measuring your room. That will help pinpoint the problem areas, but there's also a steep learning curve.
  6. If you don't want to mess with REW, you might try experimenting with your back wall first. Try removing the rear absorbers all together. Then try putting them back and covering them in kraft paper. Then do the same thing with the side wall treatments. Floyd Toole (famous acoustics guy and speaker designer) actually suggests that side wall reflections can be a good thing.
  7. What speakers are you using? You may have some unusual off axis response that when combined with the less-than-full spectrum absorption on the side walls is causing some odd frequency response in the reflected sound that reaches your ears. In which case you might want some diffusion in combination with the absorbers at the first reflection points instead of pure absorption.
You are correct on point number #2 . I do re-run eq after changes in the room but I do like your idea of removing some absorption at the rear of the room. I'm thinking about replacing some of them with diffusers. I have ominmic so will run more sweeps and look to where my issues might be. To be honest, I have focused on getting <100hz-10hz as flat as possible and now starting to focus on everything else. Maybe not the correct order but hey, I live and learn from the pro's.
Just a fyi, I have the Tekton Pens with the 1099 center.

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post #10876 of 10877 Unread Today, 02:07 PM
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Quote:
Originally Posted by BasementBob View Post
I wonder if there's a receiver with a max volume (dB(C)) limiter. So that quiet scenes are still quiet, talking scenes are easily audible (near the set max volume), but you don't scare the neighbours at the action sequences because the limit lowers the volume knob temporarily (or when you walk to the kitchen during a commercial that gets horribly loud when you're too far from the remote to shut it down)
That's basically the same effect as using dynamic range compression, or "night mode," yes? The difference being it's making the loud passages softer and the soft passages louder.
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post #10877 of 10877 Unread Today, 02:23 PM
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speaking of stone . . .
has anyone tried this flagstone gossamer from Stumps for panel covering? maybe over a black muslin?

http://www.stumpsparty.com/event/fla...mer/pgp/p0409e

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