Acoustical Treatments Master Thread - Page 206 - AVS Forum
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post #6151 of 10377 Old 04-10-2010, 09:58 AM
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Originally Posted by dooomi View Post

could I just use a thin foam batting covered in fabric... or could that be detrimental to my sound?

You could just glue the fabric directly to the sheet rock. Nothing else is needed. I'd avoid thin batting because that will absorb very high frequencies possibly skewing the balance in the room. The best type of absorption is broadband, working over as wide a range of frequencies as possible.

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post #6152 of 10377 Old 04-11-2010, 10:07 PM
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Hi Guys,

Sorry in advance for the large post. I finally got to spend some time futzing with REW.

Room - 26 x 16 x 8.
Gear Onkyo 805
Klipsch Icons
Klipsch Sub 10
Emotiva Side and Rear Surrounds.

Room has it's own sets of challenges. Mostly asymetry of the front wall between the Left and Right front stage. There is also pergo at the main stage. Carpeting covers the back half of the room and listening position. GIK 242 Panels along left and right side walls at reflection areas.

Let me know how these initial graphs look to you guys and if it looks remotely accurate or if I'm missing something completely. The stuff at 80hz is bothering me a bit. Look at that big azz null. Couple people have mentioned potential phasing issues. I just did the default sweep with all speakers connected. Sub turned on.

I need some fellow super geeks to tell me how to interpret this stuff better than I can.

First one is with no smoothing turned on



Second with smoothing


A waterfall I generated.
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post #6153 of 10377 Old 04-11-2010, 10:57 PM
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Update

Green Graph shows what happens when sub is turned OFF!

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post #6154 of 10377 Old 04-12-2010, 04:24 AM
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To determine if that is a modal null, move the microphone at least 3 feet in a diagonal direction and measure again. If you have your cross over set to 80 hz, that could be because your sub is 180 degrees out of phase from your mains at 80 Hz.

Dennis Erskine CFI, CFII, MEI
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post #6155 of 10377 Old 04-12-2010, 05:35 AM
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Are you not using a crossover to direct all low frequencies to your sub? If so, this is just asking for phase interaction problems. There are solutions, but they can be quite tricky.

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post #6156 of 10377 Old 04-13-2010, 07:47 AM
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hi everyone, i am looking for some bass traps and absorbers to help treat my movie room. i've looked at sites lite realtraps, gik, etc. though they have great stuff, i just simply can't afford them.

can you point me to some diy alternatives that can be done cheaply? thanks!
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post #6157 of 10377 Old 04-13-2010, 08:19 AM
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Quote:
Originally Posted by smokarz View Post

hi everyone, i am looking for some bass traps and absorbers to help treat my movie room. i've looked at sites lite realtraps, gik, etc. though they have great stuff, i just simply can't afford them.

can you point me to some diy alternatives that can be done cheaply? thanks!

Try here. Linked in my sig is the process I went through to add treatments ...

Jeff
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post #6158 of 10377 Old 04-13-2010, 10:25 AM
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thanks pepar.

the bass trap diy instruction is awesome.

question, is owens 703 still the preferred material for diy bass trap? is this something i can easily obtain at a local lowes or home depot? if there are better materials, please do tell. thanks!
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post #6159 of 10377 Old 04-13-2010, 11:28 AM
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Quote:
Originally Posted by smokarz View Post

thanks pepar.

the bass trap diy instruction is awesome.

question, is owens 703 still the preferred material for diy bass trap? is this something i can easily obtain at a local lowes or home depot? if there are better materials, please do tell. thanks!

Seven-O-three or something like it. I think it's a safe bet that home improvement stores do NOT have these materials. The pink-n-fluffy stuff is not the same. These acoustical treatment materials come from the "HVAC world" and to buy them - DIY - you need to get them from an HVAC insulation distributor such as this one.

Jeff
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post #6160 of 10377 Old 04-13-2010, 12:52 PM
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Pepar-

I commented on that link in another thread but maybe this is a better place for it.

I assumed that the OC703 and JM814 were superior to the Linacoustic RC since they are twice as dense (3 pcf vs 1.5 pcf). That's not the case though according to the data from your link. I added the Knauf numbers in the table below directly from their website.

No OC locally, but I was able to find the Knauf sheets locally for $68 for 20 sheets of 1" or 10 sheets of 2". Is this price reasonable?

Also, given the data below, wouldn't linacoustic be the product of choice since it shows as being equivelent in performance and I'm guessing a roll of linacoustic is a lot easier to work with than the OC703?

Product thickness density 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC
OC 703, plain 1" (25mm) 3pcf (48kg/m3) 0.11 0.28 0.68 0.9 0.93 0.96 0.7
JM Linacoustic RC 1" (25mm) 0.08 0.31 0.64 0.84 0.97 1.03 0.7
JM 814 1" (25mm) 3pcf (48kg/m3) 0.06 0.29 0.75 0.99 1.04 1.02 0.75
Knauf Insulation board 1" (25mm) 3pcf (48kg/m3) 0.08 0.23 0.62 0.88 0.96 0.99 0.65
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post #6161 of 10377 Old 04-13-2010, 01:34 PM
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Quote:
Originally Posted by NJ Jackals View Post

Pepar-

I commented on that link in another thread but maybe this is a better place for it.

I assumed that the OC703 and JM814 were superior to the Linacoustic RC since they are twice as dense (3 pcf vs 1.5 pcf). That's not the case though according to the data from your link. I added the Knauf numbers in the table below directly from their website.

No OC locally, but I was able to find the Knauf sheets locally for $68 for 20 sheets of 1" or 10 sheets of 2". Is this price reasonable?

FWIW, about two years ago I paid $125 for a bundle of 2" 703 consisting of twelve sheets x 24" x 48". I'm pretty sure that the 3pcf stuff is what is recommended by the experts.

Jeff
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post #6162 of 10377 Old 04-13-2010, 01:38 PM
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Quote:
Originally Posted by NJ Jackals View Post

Pepar-

I commented on that link in another thread but maybe this is a better place for it.

I assumed that the OC703 and JM814 were superior to the Linacoustic RC since they are twice as dense (3 pcf vs 1.5 pcf). That's not the case though according to the data from your link. I added the Knauf numbers in the table below directly from their website.

No OC locally, but I was able to find the Knauf sheets locally for $68 for 20 sheets of 1" or 10 sheets of 2". Is this price reasonable?

Also, given the data below, wouldn't linacoustic be the product of choice since it shows as being equivelent in performance and I'm guessing a roll of linacoustic is a lot easier to work with than the OC703?

Where I use the J-M Linacoustic product, I think installation was more easily accomplished with it than 703.

Jeff
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post #6163 of 10377 Old 04-13-2010, 02:00 PM
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Quote:
Originally Posted by pepar View Post

Where I use the J-M Linacoustic product, I think installation was more easily accomplished with it than 703.

Jeff

Did you fasten it in any fashion or just use spray adhesive. Am I interpreting the numbers correctly in that the Linacoustic is equivalent in performance to the rigid insulation boards?
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post #6164 of 10377 Old 04-13-2010, 04:54 PM
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Quote:
Originally Posted by NJ Jackals View Post

Did you fasten it in any fashion or just use spray adhesive. Am I interpreting the numbers correctly in that the Linacoustic is equivalent in performance to the rigid insulation boards?

I used drywall screws. It's behind a false wall and it is the 2" Linacoustic.

Rigid insulation board? Which product it that on the charts?
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post #6165 of 10377 Old 04-13-2010, 05:23 PM
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Quote:
Originally Posted by pepar View Post

Rigid insulation board? Which product it that on the charts?

I was referring to OC703, JM814, or the Knauf equivalent. (all the other guys on my chart besides the Linacoustic)
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post #6166 of 10377 Old 04-13-2010, 05:55 PM
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Quote:
Originally Posted by NJ Jackals View Post

I was referring to OC703, JM814, or the Knauf equivalent. (all the other guys on my chart besides the Linacoustic)

It is a wee bit more absorbent at 125Hz, but neither are very effective in that area making bass traps a necessity anyway. I think the 250Hz number is more important and that is where the 703 is about 33% more absorbent. And the 703 is 14% more absorptive at 500Hz. My room, anyway, needed 200Hz to 500Hz absorption and my guess is that so do a lot of others.

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post #6167 of 10377 Old 04-14-2010, 04:51 AM
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Should the ceiling and/or floor behind the screen wall be treated as well?
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post #6168 of 10377 Old 04-14-2010, 06:16 AM
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Quote:
Originally Posted by NJ Jackals View Post

Should the ceiling and/or floor behind the screen wall be treated as well?

My main concern when treating behind my false wall was comb-filtering. That is said to be less of an issue with the woven screen I have now over the micro-perforated one I had previously, but the front wall is also a first reflection point and I would have treated there anyway.

Sorry for the blather; I covered the ceiling but not the floor ... one of the two parallel surfaces. I am not an acoustician, though, so that is only my opinion.

Jeff
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post #6169 of 10377 Old 04-14-2010, 07:56 AM
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this is sad. can't get OC 703 anywhere locally. home depot requires a 60/80 piece minimum for special orders.

none of the OC distributors in my areas carry the 700 series. they too would have to special order. this stinks.

my only option is online order for 2-3x the price. ahhh....

btw, i assume that you can use OC 703 for both bass trap (corncers) as well as absorbers (sidewalls/ceilings)?
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post #6170 of 10377 Old 04-14-2010, 08:03 AM
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Quote:
Originally Posted by smokarz View Post

this is sad. can't get OC 703 anywhere locally. home depot requires a 60/80 piece minimum for special orders.

none of the OC distributors in my areas carry the 700 series. they too would have to special order. this stinks.

my only option is online order for 2-3x the price. ahhh....

btw, i assume that you can use OC 703 for both bass trap (corncers) as well as absorbers (sidewalls/ceilings)?

Shipping charges will kill you, too, by ordering online. Where are you located?
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post #6171 of 10377 Old 04-14-2010, 08:06 AM
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06110
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post #6172 of 10377 Old 04-14-2010, 08:23 AM
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LOL. This is a ripoff.

One of my local distributors quoted me $258+tax for a bundle (12 pieces) of 2x24x48 OC 703.
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post #6173 of 10377 Old 04-14-2010, 08:43 AM
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Quote:
Originally Posted by smokarz View Post

this is sad. can't get OC 703 anywhere locally. home depot requires a 60/80 piece minimum for special orders.

none of the OC distributors in my areas carry the 700 series. they too would have to special order. this stinks.

my only option is online order for 2-3x the price. ahhh....

btw, i assume that you can use OC 703 for both bass trap (corncers) as well as absorbers (sidewalls/ceilings)?

Yeah... I've been trying to find a source on and off for years. I'm in 95472.
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post #6174 of 10377 Old 04-14-2010, 08:49 AM
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Quote:
Originally Posted by smokarz View Post

06110

Closest in CT is Stratford. http://www.spi-co.com/directory.html

One in Chester, NY, too.

Call and get a quote.
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post #6175 of 10377 Old 04-14-2010, 08:50 AM
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Yeah... I've been trying to find a source on and off for years. I'm in 95472.

Benecia, CA down around the bay.

http://www.spi-co.com/directory.html
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post #6176 of 10377 Old 04-14-2010, 08:53 AM
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Benecia, CA down around the bay.

http://www.spi-co.com/directory.html

Totally cool! Thanks so much. I can drive my truck there and pick up a bunch.
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post #6177 of 10377 Old 04-14-2010, 10:06 AM
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Quote:
Originally Posted by pepar View Post

Closest in CT is Stratford. http://www.spi-co.com/directory.html

One in Chester, NY, too.

Call and get a quote.

thanks pepar. man that is going to be one long drive.
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post #6178 of 10377 Old 04-14-2010, 10:15 AM
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btw, i want the "PLAIN" type right?

they also have the ASJ (white) and FKS (silver). not sure what the differences are.

EDIT: i called and was quoted $54 for 6 piece (woot). the other two types were $80/85.
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post #6179 of 10377 Old 04-14-2010, 10:49 AM
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Quote:
Originally Posted by smokarz View Post

btw, i want the "PLAIN" type right?

they also have the ASJ (white) and FKS (silver). not sure what the differences are.

EDIT: i called and was quoted $54 for 6 piece (woot). the other two types were $80/85.

Yes, get the plain. ASJ and FRK are different kinds of facings. The plain is unfaced.
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post #6180 of 10377 Old 04-14-2010, 10:54 AM
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Quote:
Originally Posted by pepar View Post

FWIW, about two years ago I paid $125 for a bundle of 2" 703 consisting of twelve sheets x 24" x 48". I'm pretty sure that the 3pcf stuff is what is recommended by the experts.

Jeff

I just bought mine from the exact same place as Pepar and was charged $168.92 for 2 bundles of 2" 703, After reading this I'm getting worried that I ordered the right stuff! It should be in this week, but with surgery in the morning I doubt I'll pick it up till next week.
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