Why do you love OC 703 so much?

[tlindaas]

I'm a little confused about the bass absorption numbers for OC 703 and 705. Seems to me that for the typical 4 inch trap Roxul/Rockwool measures a bit better. Here are the coefficients for 125, 250 and 500hz, for both Owens Corning and Roxul:

OC 703, plain: 0.84, 1.24 and 1.24
OC 705, plain: 0.75, 1.19 and 1.17

OC 703, FRK: 0.88, 0.90 and 0.84
OC 705, FRK: 0.65, 0.52 and 0.42

Roxul Curtain Rock, Rock Board, Safe: 1.03, 1.07 and 1.12
Roxul FabRock LT, RW 40: 1.07, 1.01 and 1.07


The Roxul coefficients seem to imply a flatter room. And better absorption at 125hz. The plain OC products on the other hand have better absorption in the low mids. Thoughts?



References:

OC numbers from here: http://www.bobgolds.com/AbsorptionCoefficients.htm

Roxul numbers from here:
Curtain Rock
http://www.roxul.com/building+envelo...+curtainrock®
http://www.roxul.com/files/RX-NA-EN/...ck-3-10-09.pdf

Rock Board 40
http://www.roxul.com/building+envelo...ul+rockboard®
http://www.roxul.com/files/RX-NA-EN/...40-3-10-09.pdf

Roxul Safe
http://www.roxul.com/building+envelo...s/roxul+safe®
http://www.roxul.com/files/RX-NA-EN/pdf/RoxulSafe.pdf

Roxul FabRock LT
http://www.roxul.com/industrial/prod...rock™+lt,+ht
http://www.roxul.com/files/RX-NA-EN/...LT-3-31-10.pdf

Roxul RW 40
http://www.roxul.com/industrial/prod...w®+40,+60,+80
http://www.roxul.com/files/RX-NA-EN/...40-3-10-09.pdf

[amishsixstringe]

Different institutions tested each product. The same place has to do the test in order to have only one variable (the material).

Roxul is awesome stuff. I have a bunch in my Control room...along with 703 and spun fiberglass.

Neil

[tlindaas]

Both the Owens Corning stuff and the Roxul stuff were tested according to the ASTM C423 measurement standard.

[darkbuddha]

I don't know enough about the measurements or standards of measurement to give and informed opinion other than I think the wisdom on using 703 comes from folks that have done situational, non-theoretical, application based testing and provided those results (and their benefits and/or problems), though I don't think I'm aware of any direct A/B testing of 703 vs. Roxul products. Such testing from reputable sources tends to have more credibility than untested theoretical data among those that can't/don't/won't understand the complexity of acoustic measurements, standards, and theory.

Also, while again, I'm not clear on the measurements or standards, I have read a few places where folks raise concerns about the subjective translatability of the measurements for musical (as opposed to non-musical) applications.

BTW, did I mention I don't know much about the measurements or standards? 'cause I don't.

[Ethan Winer]

Originally Posted by tlindaas

Both the Owens Corning stuff and the Roxul stuff were tested according to the ASTM C423 measurement standard.

Sure, but labs vary all over the map. It's a sort of dirty little secret of the industry. Most labs are consistent at speech frequencies, but at 125 Hz they can vary as much as 50 percent. Much more here if you care:

Test Methods for Acoustic Treatment Products

--Ethan

The Acoustic Treatment Experts

[amishsixstringe]

Yeah, Ethan has pretty much summed up what I was talking about.

Low frequencies tested in THE SAME LAB can vary 20% or more under 100Hz.

Neil