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Dedicated Theater Design & Construction

myfipie's Avatar myfipie
08:24 AM Liked: 44
post #10351 of 10572
06-18-2014 | Posts: 966
Joined: Aug 2005
Quote:
It will be 12" X 16" filled with insulation batting.
Would be nice if they where a bit bigger, but it still should work well. Be sure to post some pictures once you are done.
byancey's Avatar byancey
09:29 AM Liked: 10
post #10352 of 10572
06-24-2014 | Posts: 262
Joined: Jun 2001
Looking for some help on the best approach for corner bass traps using Johns Manville MinWool Sound Attenuation Fire Batts. Found this for a great price at my local Lowes. It comes in packs of 10 16"x48"x3" Batts. It appears to be comparable to OC703 at similiar thickness (slightly less effective at the very low end), but for the price I paid, I can double stack these and it would still be far more cost effective than a sheet of OC703. These are batts rather than rigid boards, but they do appear to be very solid and easy to work with (more stable and less smelly than Roxul SafeNSound). Here's the sound coefficients from JMs spec sheet for the batts.



I have a false screen wall two feet from my actual wall which I recently added to my Theater specifically for the purpose of hiding sound treatments. Still thinking about how much treatment to put in there along the back wall, but I do know I want corner bass traps. It seems that super chuck traps are more common with softer materials as opposed to corner spans with more rigid materials such as OC703. However, at only 16" wide, I'll end up with super chunks that are 16" on the sides and about 22" on the diagonal (stacked floor to ceiling). Is this a large enough trap to be effective given my material?

The other approach I've considered is cutting the sheets in half and doubling them up to create a 16"x24"x6" block and then tapering the 16" edge and stacking these diagonal across the corner on the 24" edge..effectively spanning the full corner 6" deep with an air gap behind.

The superchunk approach would use about 11 batts to completely fill a corner. The fill would be solid, but less surface area on the diagonal.

The spanning approach would only use 6 batts to fill the same corner. This yields more surface area on the diagonal, but with an air gap behind rather than solid fill.

Given that I have the space to work with, doubling up the batts and spanning the corner seems like the obvious approach to me. Would love to hear input from others in this forum? Is my logic sound here, or will I get more benefit from the smaller superchunk approach?
Attached: JM MinWool Coefficients.jpg (53.5 KB) 
sigma722's Avatar sigma722
02:03 PM Liked: 10
post #10353 of 10572
06-24-2014 | Posts: 8
Joined: Nov 2007
Do any of you have any extraordinary posts/threads saved that help explain acoustic treatments with the what why where how?

This thread seems like an awesome discussion, but I was kinda hoping to have a nice OP similar to the sound isolation thread to help point me in the right directions.

Thanks!
ellisr63's Avatar ellisr63
04:12 PM Liked: 253
post #10354 of 10572
06-24-2014 | Posts: 2,172
Joined: Jul 2002
Our front stage is just a short bit that extends to behind our AT screen... I was thinking og using a hole saw to make some holes in the curved front and then stuff the whole stage with insulation... Will that work as a bass trap? Here is a picture of our front stage...

Under the center channel is a Danley DTS-10 which comes up to the front of the stage,,, We will be sealing the mouth of the sub to the stage. The left and right speakers will be installed at the same level as the center by making a 2x4 framework... Under the left and right there will also be fiberglass insulation. I am also debating on using some rubber matt I have to hang from the ceiling behind the speakers and then fill the cavity behind the rubber with insulation (floor to ceiling)... Does this sound like a good idea? Any suggestions?

tia,
Ron
myfipie's Avatar myfipie
04:35 AM Liked: 44
post #10355 of 10572
06-25-2014 | Posts: 966
Joined: Aug 2005
[QUOTE=sigma722;25229322]Do any of you have any extraordinary posts/threads saved that help explain acoustic treatments with the what why where how?

This thread seems like an awesome discussion, but I was kinda hoping to have a nice OP similar to the sound isolation thread to help point me in the right directions.

Thanks![/QUOT

See some of the following videos and articles to see if this gives you a hand.

http://www.gikacoustics.com/educational-videos/
http://www.gikacoustics.com/articles/
BamaDave's Avatar BamaDave
04:12 PM Liked: 26
post #10356 of 10572
06-28-2014 | Posts: 201
Joined: Feb 2007
Does anyone know the basis for positioning the overhead ceilingdiffusors? In Anthony Grimani home theater design heuses the overheads just behind the listener and I trying to get a betterunderstanding on how to determine the best spot to add them. Any expert opinions?
Here is a link toan example of what I'm talking about. Funny enough, my wife actually likes the look!
http://www.soundandvision.com/content/acoustics-101
PrimeTime's Avatar PrimeTime
07:21 PM Liked: 48
post #10357 of 10572
06-28-2014 | Posts: 1,813
Joined: Mar 2003
Quote:
Originally Posted by baloo_btru View Post
I am trying to get the double use of blacking out a short side wall to minimize light and sound reflections. The wall is approximately 6'x9' and I want to cover the whole thing in something as thin as possible (definitely not 2"+; max 1" but thinner would be great) that will provide better sound response than drywall and won't reflect as much as even matte paint.
Consider black olefin indoor/outdoor carpet. Definitely less reflective than paint (quite useful behind Acoustically Transparent projection screens). Widely available at carpet warehouses; Depot has it too (possibly as a Special Order).
baloo_btru's Avatar baloo_btru
10:18 AM Liked: 108
post #10358 of 10572
06-29-2014 | Posts: 716
Joined: May 2007
Quote:
Originally Posted by PrimeTime View Post
Consider black olefin indoor/outdoor carpet. Definitely less reflective than paint (quite useful behind Acoustically Transparent projection screens). Widely available at carpet warehouses; Depot has it too (possibly as a Special Order).
Thanks. Does that do much with the sound?
PrimeTime's Avatar PrimeTime
07:37 PM Liked: 48
post #10359 of 10572
06-29-2014 | Posts: 1,813
Joined: Mar 2003
Carpet on the walls absorbs almost everything above 4 kHz, a lot above 1 kHz, some above 250 Hz and not much below that. Some might consider that a little too "dead," but a little EQ and tweaking of the modern surround processing (assuming you have "side" surround radiators) can dial in whatever "live" acoustical property your heart desires, free of the reflections and effects of the (previiously) live wall.

The thing about carpet on drywall, you might not want to just "go for it" and glue it to the drywall as that is sorta permanent (as in, replace drywall when dissatisfied). One way around that is to cut the wall carpet to size and glue it to an intermediate membrane (such as rigid foam or, in my case, plastic trellis). Once this assembly is dry, mark the carpet where the wall studs will be (with masking tape) and attach it to the wall with an 18-gauge finish nailer, The nap of the carpet will hide the fasteners, and you can take it down quickly if you change your mind (or move), and will only have a little spackling and repainting for the drywall to be good as new.
Maklar's Avatar Maklar
10:03 PM Liked: 18
post #10360 of 10572
06-29-2014 | Posts: 159
Joined: Jul 2004
A quick question, I see a lot of information on diy absorbers but can anyone point to some diy diffusers and slat scatterers?
myfipie's Avatar myfipie
06:18 AM Liked: 44
post #10361 of 10572
06-30-2014 | Posts: 966
Joined: Aug 2005
Quote:
Originally Posted by Maklar View Post
A quick question, I see a lot of information on diy absorbers but can anyone point to some diy diffusers and slat scatterers?
Does not show you how to make them but does do the calculations for you.
http://www.mh-audio.nl/ACalculators.asp#showcalc
BamaDave's Avatar BamaDave
10:50 AM Liked: 26
post #10362 of 10572
06-30-2014 | Posts: 201
Joined: Feb 2007
????????????????


Quote:
Originally Posted by BamaDave View Post
Does anyone know the basis for positioning the overhead ceilingdiffusors? In Anthony Grimani home theater design heuses the overheads just behind the listener and I trying to get a betterunderstanding on how to determine the best spot to add them. Any expert opinions?
Here is a link toan example of what I'm talking about. Funny enough, my wife actually likes the look!
http://www.soundandvision.com/content/acoustics-101

Nightlord's Avatar Nightlord
12:29 PM Liked: 165
post #10363 of 10572
06-30-2014 | Posts: 1,994
Joined: Feb 2009
You may want to diffuse, or partially diffuse the first reflection location(s). You may also want to dampen the area above and partially towards the first reflection.

Myself, I'll just use interleaved wood (3"x2" with 2" spacing) panels going lengthwise in the room for diffusion, that's what my acoustician ordered for my room, but I have dampened above the speakers on my own accord... His comment was "at worst it won't worsen anything"
Maklar's Avatar Maklar
09:39 PM Liked: 18
post #10364 of 10572
06-30-2014 | Posts: 159
Joined: Jul 2004
Quote:
Originally Posted by myfipie View Post
Does not show you how to make them but does do the calculations for you.
http://www.mh-audio.nl/ACalculators.asp#showcalc
Thanks, I also found a thread in the diy speakers, I limited my initial search to just the dedicated theater area.

DIY Sound Diffusers
ellisr63's Avatar ellisr63
10:05 PM Liked: 253
post #10365 of 10572
06-30-2014 | Posts: 2,172
Joined: Jul 2002
Quote:
Originally Posted by ellisr63 View Post
Our front stage is just a short bit that extends to behind our AT screen... I was thinking og using a hole saw to make some holes in the curved front and then stuff the whole stage with insulation... Will that work as a bass trap? Here is a picture of our front stage...

Under the center channel is a Danley DTS-10 which comes up to the front of the stage,,, We will be sealing the mouth of the sub to the stage. The left and right speakers will be installed at the same level as the center by making a 2x4 framework... Under the left and right there will also be fiberglass insulation. I am also debating on using some rubber matt I have to hang from the ceiling behind the speakers and then fill the cavity behind the rubber with insulation (floor to ceiling)... Does this sound like a good idea? Any suggestions?

tia,
Ron

Is this a good idea... Or should I leave it empty under the stage and open in the rear, and just cover the rear walls with insulation?
Nightlord's Avatar Nightlord
12:46 AM Liked: 165
post #10366 of 10572
07-01-2014 | Posts: 1,994
Joined: Feb 2009
You can never have too much bass trapping, don't waste the opportunity!
ellisr63's Avatar ellisr63
08:43 AM Liked: 253
post #10367 of 10572
07-01-2014 | Posts: 2,172
Joined: Jul 2002
Quote:
Originally Posted by Nightlord View Post
You can never have too much bass trapping, don't waste the opportunity!
Would a 3" hole saw be big enough for cutting the holes in the front of the stage? Do I need to use acoustic fabric on the front or can it be carpet?
PrimeTime's Avatar PrimeTime
09:32 AM Liked: 48
post #10368 of 10572
07-01-2014 | Posts: 1,813
Joined: Mar 2003
Carpet is pretty transparent at low frequencies. More rugged and, over time, more uniform than fabric.
ellisr63's Avatar ellisr63
12:21 PM Liked: 253
post #10369 of 10572
07-01-2014 | Posts: 2,172
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When making the wall acoustic materials... Do I need to leave a gap to the wall or do they go flush to the wall?
Nightlord's Avatar Nightlord
01:34 PM Liked: 165
post #10370 of 10572
07-01-2014 | Posts: 1,994
Joined: Feb 2009
Quote:
Originally Posted by ellisr63 View Post
When making the wall acoustic materials... Do I need to leave a gap to the wall or do they go flush to the wall?
Depends om if the materials are acoustically (semi-)transparent or not. If they are, then leaving a gap is often a bonus. If they aren't- then up against the wall with them to preserve room size.
myfipie's Avatar myfipie
09:01 AM Liked: 44
post #10371 of 10572
07-02-2014 | Posts: 966
Joined: Aug 2005
Quote:
Originally Posted by ellisr63 View Post
When making the wall acoustic materials... Do I need to leave a gap to the wall or do they go flush to the wall?
I highly recommend a gap if you can afford giving up the extra space. Even a 1" to 2" or so will help.
BB1111's Avatar BB1111
11:53 AM Liked: 14
post #10372 of 10572
07-02-2014 | Posts: 178
Joined: Sep 2010
Wonder if I can get some help for my room treatments. Would like a once-and-for-all setup answer since I've been experimenting with treatments for what seems like ages now.

I have trouble getting a solid answer because all my speakers are electrostatics and nobody seems to have that much experience treating them and handling the back-wave.

I've attached a few pictures of the room and measurements from REW, ignore the A,B,C, etc red boxes in the room picture, the brown boxes are where the speakers are and I've also added wide channels at 60 degrees from the MLP.

What would you guys recommend? I can post more graphs later tonight, subs are placed at the B and C positions.

Thank you

http://imgur.com/a/l8Dmu

Dual Subs with Audyssey on:

http://i.imgur.com/KPflKGA.png
PrimeTime's Avatar PrimeTime
06:15 PM Liked: 48
post #10373 of 10572
07-03-2014 | Posts: 1,813
Joined: Mar 2003
Electrostatics, or dipole radiators of any kind (Magneplanars, etc) are a whole different ballgame.

Some people prefer dipoles because of the ethereal presence that the backwave creates. (Some people like the old Bose 901 schtick too). Other people perceive this added presence as "muddying" the sound. It is a matter of taste, and does indeed complicate the problem of how to "treat" the acoustical space.

The nice thing about dipoles is that their radiation pattern usually nulls out some of the off-axis sound that would otherwise tend to produce the dreaded "early reflections."
myfipie's Avatar myfipie
05:42 AM Liked: 44
post #10374 of 10572
07-04-2014 | Posts: 966
Joined: Aug 2005
Quote:
Originally Posted by BB1111 View Post
Wonder if I can get some help for my room treatments. Would like a once-and-for-all setup answer since I've been experimenting with treatments for what seems like ages now.

I have trouble getting a solid answer because all my speakers are electrostatics and nobody seems to have that much experience treating them and handling the back-wave.

I've attached a few pictures of the room and measurements from REW, ignore the A,B,C, etc red boxes in the room picture, the brown boxes are where the speakers are and I've also added wide channels at 60 degrees from the MLP.

What would you guys recommend? I can post more graphs later tonight, subs are placed at the B and C positions.

Thank you

http://imgur.com/a/l8Dmu

Dual Subs with Audyssey on:

http://i.imgur.com/KPflKGA.png
First thing I would do is flip the room to face the lower wall. That is going to give you much better symmetry which will result in better imaging. From there I would bass trap all the corners in your room, use diffusion for behind the speakers and early reflection points, and do a combination of diffusion/absorption on the back wall.
Nightlord's Avatar Nightlord
02:01 PM Liked: 165
post #10375 of 10572
07-04-2014 | Posts: 1,994
Joined: Feb 2009
Quote:
Originally Posted by PrimeTime View Post
The nice thing about dipoles is that their radiation pattern usually nulls out some of the off-axis sound that would otherwise tend to produce the dreaded "early reflections."
Which also makes them ideal for placing close/against side walls if you have lack of space.

*still want to hear what IB-mounted Magnepans can do...i think it would be astounding...*

(FYI: have owned MG1.4:s somewhere back in time...)
ellisr63's Avatar ellisr63
08:10 PM Liked: 253
post #10376 of 10572
07-04-2014 | Posts: 2,172
Joined: Jul 2002
Quote:
Originally Posted by Nightlord View Post
Which also makes them ideal for placing close/against side walls if you have lack of space.

*still want to hear what IB-mounted Magnepans can do...i think it would be astounding...*

(FYI: have owned MG1.4:s somewhere back in time...)
I remember years ago seeing an article where someone made a false wall and mounted some MLs in them.... They had a port in the wall for the backwave on each side of the MLs.
BB1111's Avatar BB1111
07:38 PM Liked: 14
post #10377 of 10572
07-06-2014 | Posts: 178
Joined: Sep 2010
Quote:
Originally Posted by myfipie View Post
First thing I would do is flip the room to face the lower wall. That is going to give you much better symmetry which will result in better imaging. From there I would bass trap all the corners in your room, use diffusion for behind the speakers and early reflection points, and do a combination of diffusion/absorption on the back wall.
Thank you for the response.

I currently do have 4x BAD RPG panels that I DIY'd a while ago, they are pretty nice made out of maple and I would like to incorporate them into the room if possible. Currently they are on the left and right wall at the first reflection points. Are these enough diffusion or should I move them to the back of the room and add true diffusers to the front of the room as you suggest? ( I would probably DIY the fractal diffuser from Arqen)

Also what benefit will the diffusers in front give me? What will it do to the sound field, imaging, characterstics of the speaker.. etc
badger985's Avatar badger985
11:23 AM Liked: 10
post #10378 of 10572
07-11-2014 | Posts: 23
Joined: Jun 2014
I was looking to make corner bass traps, and was going to buy Owens Corning 703 and cut them into the correct dimensions, however when doing research I found the following

Owens Corning "Select Sound" Black Acoustical Board 2" inch thick has an NRC of 1.00 the same as 703, but it also states that this reduces sound reverb, which 703 does not. Would this be a better product to create Bass Traps out of?

Please advise, I have tried doing research but I have found very little on these boards about this. Thank you.


Badger
myfipie's Avatar myfipie
01:26 PM Liked: 44
post #10379 of 10572
07-11-2014 | Posts: 966
Joined: Aug 2005
Quote:
but it also states that this reduces sound reverb, which 703 does not.
Both are going to reduce "reverb" in a room. Not sure what the density is of the other, but 4" 703 straddling the corner will work very well. If you plan on filling the corner then you want to use the less dense of the two.

NCR of 1 really does not tell you want it is doing on the low end, just what it is doing over all. Not a bad thing to look at but when looking at numbers you want to look at the low end test results vs the upper frequencies. Hope that makes sense.
coolgeek's Avatar coolgeek
09:41 PM Liked: 148
post #10380 of 10572
07-11-2014 | Posts: 1,887
Joined: Sep 2011
I am looking to build a gentle diffusion.. and was thinking of using those 'vinyl tiles' that people use for flooring would work?

Do the vinyl absorb the sound or reflects them? If they absorb, then it won't work.

I was thinking of getting those and then bend them to semi-round... it's easy to build.. just put a bunch of them in right angles, bent into half round shapes...

Basically something like below (contour type diffusers) but built out of vinyl floor tiles rather than wood:




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