4" bass traps spacing

[Joji]

Hi,
I am building some 4" bass trap. when I mount them on the wall I hear it is better to have 2-3" space between the trap and the wall. Is this done in the trap where the 2" space is in the back of the panel or do you mount them 2" away from the wall. also should you do this with 6" bass tracps as well.

Also does anyone know in LA, sanfornando, valencia or simi valley in CA where you can get owen corning 703, Rockwool, or whatever material works well for bass traps.
thanks

[Joji]

I looked up Roxul

here is a link
Roxul Safe®

Here are the specs

Acoustical Performance:
ASTM C423
CO-EFFICIENTS AT FREQUENCIES
Thickness 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz NRC
2.0" 0.26 0.68 1.12 1.10 1.03 1.04 1.00
3.0” 0.63 0.95 1.14 1.01 1.03 1.04 1.05
4.0” 1.03 1.07 1.12 1.04 1.07 1.08 1.10
Compressive Strength:
ASTM C 165 at 10% 144 psf (6.9 kPa)
Density:
ASTM C 612-00 Actual 4.5 lbs/ft³ 72 kg/m³
Dimensions:
24” (width) x 48” (length) [610 mm (width) x 1219 mm (length)]
Thickness:
Product thickness is available in 2”, 3”, and 4”.




Is the higher the pound density the better. this says 4.5 or is tit the lower the density. also the co-efficient at 125hz says 1.04 compared to others that say .83 or.86

Is there a big difference between .86 density and 1.04 or is it like splitting hairs

thanks

[avare]

Originally Posted by Joji

Is the higher the pound density the better. this says 4.5 or is tit the lower the density. also the co-efficient at 125hz says 1.04 compared to others that say .83 or.86

It depends on the thickness, teh thicker the panel, the better a lighter material is. At 4" the 4.5 lb/ft3 is just about optimum.

Andre

[SeniorityFedup]

Originally Posted by avare

It depends on the thickness, teh thicker the panel, the better a lighter material is. At 4" the 4.5 lb/ft3 is just about optimum.

Andre

Hello andre,
interesting to learn as l have read on here before that a personal preference amongst another designer in this topic is say 8lbs (and if memory serves me right, it would be for 4" panels) .Do l pressume you will state this not to be optimum? Thank you mr avare.

[ejsongs]

cwci in city of industry is the only place to get 703 in la off of the 60 freeway.

they only sell 703 2" in 12 panel bundles.

BUT

considering the cost of gas and time i've started ordering online and having it shipped to me. try ats.

the cost difference was maybe $20 but if you take in the account the 2hrs out of your day and gas just to get it online seemed like a better option.

you can get roxul and the james mansfield equivalent to 703 and viking insulation in burbank.

ej

ps if you do decide to go down to cwci and buy some 703 but end up with extra let me know as i need to buy 3 more sheets. i'll buy some extras off you if you don't need them

[Glenn Kuras]

Originally Posted by SeniorityFedup

Hello andre,
interesting to learn as l have read on here before that a personal preference amongst another designer in this topic is say 8lbs (and if memory serves me right, it would be for 4" panels) .Do l pressume you will state this not to be optimum? Thank you mr avare.

I have always found 8 pound to be optimum at 4", but 4.5 lb/ft3 I am sure is fine.

thumbsup

[The Convicted]

Rock wool 8lb density
Mcmaster Carr
$10.67 per panel
2' x 4' x 2" thick

I just picked up 12
The Are in Santa Fe Springs, near Downy Ca

[Glenn Kuras]

Originally Posted by The Convicted

Rock wool 8lb density
Mcmaster Carr
$10.67 per panel
2' x 4' x 2" thick

I just picked up 12
The Are in Santa Fe Springs, near Downy Ca

[Lonely Raven]

Originally Posted by Glenn Kuras

I have always found 8 pound to be optimum at 4", but 4.5 lb/ft3 I am sure is fine.

thumbsup

Originally Posted by The Convicted

Rock wool 8lb density
Mcmaster Carr
$10.67 per panel
2' x 4' x 2" thick

I just picked up 12
The Are in Santa Fe Springs, near Downy Ca

Originally Posted by Glenn Kuras

That's the same density I have. Am I building poor bass traps if I use 8pcf at 8"?

I keep getting mixed info on this.

[Millo 3.1]

General question:

Looking at the typical Bob Gold's thing I find interesting that there are no tests of mineral wool material beyond 6" deep, and that 8lb density material is only tested up to 4"... is it because at 6" of depth it starts becoming counter-productive? It seems on that list, at 4" of depth, 8lb mineral wool is the best performer in the low end. The only 6" deep are of 4lb density.

Because of this list, I had thought of getting 4lb density mineral wool for any 6" deep absorbers, and 8lb for 4" deep absorbers.

I believe 3lb density fiberglass OR 4.5 lb density mineral wool are the typical recommendations for a 24"x17"x17" chunk--that right? How about a large chunk w/ 2' sides and almost 34" face?