Johns-Manville rigid fiberglass.

[pdlstl]

I hope it's okay to post this this here. I originally posted this earlier today at homerecording.com.

Don't know if this has been posted before or not but it sure enlightened me.

http://www.jm.com/insulation/faqs/69.htm

Scroll down for the Sound FAQ's.

Like everyone, I've been searching for a supplier who carries OC 703 (or 705) in the Fort Worth, TX area. However, I came across a supplier who carries the Johns-Manville 800 Series Spin-Glas. This is supposed to be the JM equivalent of the OC 700 Series.

The specs of the JM vs. OC follows:

JM 814 plain 2"

125-0.24
250-1.00
500-1.11
1000-1.08
2000-1.06
4000-1.05
NRC-1.05

OC 703 plain 2"

125-0.17
250-0.86
500-1.14
1000-1.07
2000-1.02
4000-0.98
NRC-1.00

My room is 14'x16'x9' (ceiling). The walls are painted sheetrock, the ceiling is sheetrock with a popcorn surface (blown-on) and the floors are terra cotta tile. The room has frequencies bouncing all over it.

The focus is on acoustic music, primarily bluegrass. No drums/amps.

I want to make panels to hang on the walls/ceiling for some absorption/reflection control.

Will the JM product be just as good as the OC absorption across the spectrum?

Thanks,

Earl

[AVare]

The products are the same acoustically.

Enjoy!

[Herwert]

Speaking about comparing and acoustic equivalency; what about this product:

The Sonepanel seems a good option for OC 703 in Holland but my only concern is: are they acoustically the same?
Because OC 703 is a rigid fibreglass but Sonepanel is not a fibreglass product. It's a glaswool product with a glasfilm (thin glas skin) on one side.

with these coefficients of the 703 ( 3.0 pcf (48 kg/m3) )
2" (51mm) 0.17 0.86 1.14 1.07 1.02 0.98 1.00
3" (76mm) 0.53 1.19 1.21 1.08 1.01 1.04 1.10
4" (102mm) 0.84 1.24 1.24 1.08 1.00 0.97 1.15

The comparison Sonepanel has these coefficients:
40 mm 0.34 0.53 0.86 0.85 0.81 0.89 0.75
50 mm 0.24 0.57 0.88 1.01 0.94 0.90 0.85
90 mm 0.74 1.08 1.09 0.97 0.91 0.94 1.00

Note that for the lower frequencies the 40mm does a better absorption than the 50mm... so for low frequencies the 40mm would be better than the 50mm?

How well can I use this product instead of the 703?
Does it matter that is is not a fibreglass but a glasswool product?
What about the weight? Does this matter? 703 has a 48 kg/m3 and I cannot find any ratings on the Sonepanel.

Regards Herwert.

[AVare]

There are diferences in measurong absoprtion between Europe and Norht America. It is hard for me to compare those reults directly.

MAterial type is not htat important. Density is, find out what it is.

USe Bob's absorption pagehttp://www.bobgolds.com/AbsorptionCoefficients.htm

Good luck!
Andre

[Herwert]

Hello,

And what about this product: Ductliner 602

http://www.isover.nl/toepassingen/produ ... r_602.html

It absorbs almost the same as the 703 at the same thickness.
50mm 0.32 0.70 1.09 1.07 0.99 1.25
100mm 0.84 1.25 1.21 1.04 1.00 1.29

This product is very close to the 703. right?

Sorry, to say this but I still don't get why the density does matter? All what counts is are the absorption coefficients, isn't that right?

See picture how it looks.

Regards Herwert.

[AVare]

Instead of asking us to research different products by name/make, use this excellent resource:

http://www.bobgolds.com./AbsorptionCoefficients.htm

It should answer all your material questions.

Andre