John Sayers' Recording Studio Design Forum Archive

Found this link while investigating for 703.

They claim an NRC of 1.05, which could mean anything, and certainly gives no information about LF absorption, and it seems to be a 2" 2x4, 6 pcf board.

It's listed on Bob Gold's absorption coefficient site with out and NRC's listed.


Clincher is its 4.80 for 8 sheets of 2"


Thats a steal. If this is usefual, i'm gonna buy a ****load. And go into business, jeez.

Not really, but.... maybe somebody has some experience with it?

http://www.acoustic-material.com/HTML/thru-walls.html



link would help ;]

Gotta watch the wording - "2' x 4' x 2" sheets - $4.80 each 8-sheet bundle" may really mean, 2' x 4' x 2" sheets - $4.80 each, 8-sheets PER bundle - this would be more in line with typical pricing. The stuff sounds/looks like rockwool, which typically goes for about that price for ONE 2x4 foot piece.

Also, even tho the materials may be OK, don't listen to any of their "sound proofing" advice; the diagram with the limp mass is a 3-leaf wall with WORSE TL at low frequency than if the center stuff were left out... Steve

got you..... i thought that for a moment, and then thought that if this stuff is decent at LF absorption, 4.80 each is still pretty decent for what I've found. Got to call a few other places tomorrow when they are all open however.

I'm thinking of not risking the stuff thats not rated anywhere for LF and just spending a couple hours on the phone finding some straight 703.

Tell me if i'm remembering my RSD forum classtime however:

The difference between 3 pcf stuff and 6 pcf stuff is that the 6 pcf density is a bit more effective at bass frequency's, but it's increased density starts to reflect some highs, is that right?

I mean, i'm going to be building free standing gobo type absorbers, and installing absorption into the ceiling...... I understand the importance of bass trapping, but I'd like to tame the HF's and reverb time as well, that's why I'm wondering if I should get the straight up 3 pcf OC 703 rather than any 6 pcf stuff.

Isolation is not a concern of mine. I'm only interested in how it sounds inside the room, and outside noise isn't a problem. (And when it is, I won't be recording....... but I certainly am not bothering the Auto Glass shop or the Cuyahoga River.)


No neighbors to speak of, so i've really lucked out.

well, anyway, thanks for the reply steve

I'm thinking of not risking the stuff thats not rated anywhere for LF and just spending a couple hours on the phone finding some straight 703.

Why 703? Ypu know about Bob Golds' absorption data. Off the top of head, Fibrex and Roxul have factories close to you. Not to mention Knauf, JM etc.

Andre

well, I called that place, and as it turns out, they have just as good prices on 703 (or equivalent) as the other places around here (.80/sq ft.)

they do however, have 100 24" x 21" pieces of that S.A.B., which I found data for at IIG's website,

http://www.iig-llc.com/Contenet/Downloadsxl.htm

and a pallet of 100 of those <2 ft^2 is only 50$..... could build 50 21" by 48" panels out of that....[/url]

It's the minwool 1200 sound attenuation fire batts

Anyway, I think I'm just going to go for that. Beats .80 per sq ft

For what you're doing, you're correct on the 3 vs 6 pcf thing; one additional way to get "best of both" would be if you build absorbers with the 6 pcf stuff inside, then 2-4" of the "fluffy stuff" as an outer sheath; this will absorb mids/highs better at off angles than the higher density stuff, and the high density "core" will take care of the bottom.

Just a thought... Steve

and a great thought at that.....

I'm trying to arrange a pickup truck at the moment, freight on 1 pallet is 90, 2 pallets is 140.....

I should also ask..... would have trouble (contruction/craft-wise) making a single 21x 48 panel out of two 21 x 24 pieces of this stuff?

Actually, on the same note, is there any reason why I shouldn't simply make smaller 21x 24 panels? Or, for that matter, 42 x 48, etc. I mean, is the size of the things really just determined by where the panels will fit into the room, or is there some optimum size for an absorber?

I was also thinking of making a couple 4 x 6 stand mount panels, and maybe 3 or 4 2' by 4' standing panels. To help with separation and RT control that is..... would it be worth my while?

Thanks for the responses guys, by the way, I appreciate them quite a lot. Really trying to get this place making a buck, and I just can't in good conscience promote this room as a "studio" with the way it sounds. (muddy in the low end and confused in the high)

anyway
thanks

The muddy lows will tighten up with corner absorbers, try for at least 3 feet wide diagonally across the corners. I'd use 3PCF or at least the fluffy covers if using 6 pcf here. The highs will clean up with a fair sized cloud over the mix area, especially if your present ceiling is reflective.

I would definitely build a few free-standing absorbers while you're at it; you will probably find you like mixing with most of the wall behind you hidden by absorbers placed a couple of feet away from the wall.

Little point in making panels much smaller than 2x4 feet IMO... Steve

thanks steve, much appreciated.

I think, however, i'm just going to have to do with the 6 pcf stuff.

http://www.iig-llc.com/Downloads2004/II ... 004-04.pdf

thats the stuff, 1260, not too bad

absorption coefficients for 125 is .25, and .85 at 500, the rest are "over" 1.00

Just gonna do most of it this week and weekend and monday, see how low I can get the rt60 and how even i can get that lowend response.

Thanks for all the advice

You're welcome; remember though, when using high density absorbents that their absorption values are measured at 90 degree incidence; a room is RARELY under those conditions, and the higher density will tend to make "grazing incidence" performance worse than with the 3 pcf stuff. That's the reason I suggested placing "fluffy stuff" in FRONT of the 6 pcf.

Bottom line is your ears though; you'll know if you need the fluffy's after you have the other stuff in place. For that reason, I'd hold off on any covering until you're sure... Steve