Sorry, that "2x thickness" wasn't right - 3" S&S seems to perform between 2" and 3" OC 703, and closer to 3" if anything:

Code:
Product 	 	density 125hz 	250hz 	500hz 	1000hz 	2000hz 	4000hz 	NRC
RXL 80 		1.5"  	8.0 pcf 0.21 	0.64 	0.92 	1.00 	0.95 	1.01 	0.90
Safe‘n’Sound 	3"  	2.5 pcf 0.52 	0.96 	1.18 	1.07 	1.05 	1.05 	1.05

703, plain 	1"  	3.0 pcf	0.11 	0.28 	0.68 	0.90 	0.93 	0.96 	0.70
705, plain 	1"  	6.0 pcf	0.02 	0.27 	0.63 	0.85 	0.93 	0.95 	0.65
703, plain 	2"  	3.0 pcf	0.17 	0.86 	1.14 	1.07 	1.02 	0.98 	1.00
703, plain 	3"  	3.0 pcf	0.53 	1.19 	1.21 	1.08 	1.01 	1.04 	1.10

source

I am actually using Comfortboard IS rather than RXL 80, but apparently the two have very similar behaviour.

One thing I don't understand is that the absorption coefficients don't go up that much at high frequencies as thickness increases, but I was also under the impression that adding layers would more or less result in adding the absorption coefficients. I guess the latter belief must be wrong ?


Edited by bridgman (02/11/17 12:43 PM)
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