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Which Knauf?
Old 18th September 2011
Here for the gear

Which Knauf?

I'm about to put a bunch of money into 2" thick Knauf boards. I'm planning on making 4" thick broadband absorbers with 3 pcf and 1'x1' triangle superchunk basstraps with 6pcf. First off, I'd like to confirm with you guys that I am on the right track.

Second, I'm not sure which product to purchase. There is the regular insulation boards with ecose -
Knauf Insulation Board with ECOSE® Technology

and then the acoustical board smooth with ecose -
Knauf Acoustical Board Smooth with ECOSE® Technology

According to absorption coefficient charts, the 3pcf regular insulation boards are very similar to the 3pcf acoustic smooth in the higher frequencies, but the acoustic smooth begins to perform better starting around 500hz and below. And the 6 pcf densities of both versions are identical. Can anyone recommend one over the other? And does anyone know where I can find a more comprehensive absorption coefficient measurements for these products?

Thanks for your help!
Old 18th September 2011
Gear Guru

The 6 pcf one has better absorption figures. Also stiffer, less likely to sag.
The ASJ versions have quite high LF figures, interesting. A 1x1 SSC is very small, have you options space wise. Have you seen GIK Soffits?
Old 18th September 2011
Here for the gear

Yes I have room to work with. The space is 16x10x8' with minimal hardware. The reason I was thinking 1'x1's is so that I can maximize the amount of corners covered with the money I have. I read somewhere on here that coverage is better than thickness, but is that not the case here? I forget where I read that.

I had not seen the soffit traps before. In my mind I was set on triangular traps in the corners, I guess for aesthetic reasons, but now I am reconsidering. The soffit style would be more effective and easier to build and they look clean as hell! I would have to increase my budget considerably though. Not sure I can afford that.

I've read on gs that the Knauf 3 pcf is similar to 703, making it better for broadband absorbers and that the 6pcf is similar 705, making it more desirable for bass traps. But now looking at these charts, they seem to be fairly simiar. Anyway are you suggesting I just get all 6 pcf? Rigidity is not an issue because I will be building frames

Thanks for your response Dan!
Old 18th September 2011
Gear Guru

I thought you meant just one SSC one foot wide!
Area and depth are both desireable. More depth would reach further down in frequency though.
For deep traps, e.g. SSC's or square versions the lighter 3pcf would be better. For standalone panels 4 inches thick I would use 6pcf, but if your frames prevent sagging, particulary in the cloud version, and if the numbers are similar at 4 inches, then by all means use the cheaper 3pcf.
Old 18th September 2011
Here for the gear

So would the only reason for using 3pcf be cost? Is there no actual acoustic benefit to using 3 pcf instead of 6 pcf?
Old 18th September 2011
Gear Guru

Depth and density (more accurately Gas Flow Resistivity) and absorption are all interlinked.
At 4 inches the 6pcf is best, read the charts! At 12 inches the best may be as low as 1 to 2 pcf.

Old 19th September 2011
Here for the gear

What am I missing here? I don't see 4" 6pcf on the charts.
Old 20th September 2011
Gear Guru

Thats strange doob, I see it.
Which Knauf?-screen-shot-2011-09-20-02.09.26.png

Old 28th September 2011
Gear Nut
Insulation Man's Avatar

I'm pretty sure the Acoustic Smooth is the same product as the regular Fiberglass Board, just different names by the manufacturer. These manufacturers do this alot with products with multiple purposes, so they can sell the same product to two different types of distributors. Buy whichever one is priced less.
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