Layering 1.5" OC70x + 3" Roxul S&S = effective?

[darkbuddha]

Would it be effective to layer 1.5" OC703 (3.8 pcf) with 3" Roxul S&S (2.5 pcf) for bass traps and/or broadband traps? If so, with or without and air gap behind? Should the OC703 on top, or the Roxul S&S?

I can get 1.5" OC70x locally very easily ($125 for four 4'x10' panels), but the 3" Roxul is still half the cost ($50 eight 3" panels). My thought was it might be cost effective to combine the two to obtain 4.5" deep panels that would perform well.

Thoughts?

[avare]

Originally Posted by darkbuddha

Would it be effective to layer 1.5" OC703 (3.8 pcf) with 3" Roxul S&S (2.5 pcf) for bass traps and/or broadband traps? If so, with or without and air gap behind? Should the OC703 on top, or the Roxul S&S?

I can get 1.5" OC70x locally very easily ($125 for four 4'x10' panels), but the 3" Roxul is still half the cost ($50 eight 3" panels). My thought was it might be cost effective to combine the two to obtain 4.5" deep panels that would perform well.

No. Just use the S&S. Double it up. If you do not want an absorber 6 or 7" thick, compress the material to 4.5".

Andre

[darkbuddha]

Thanks... keep it simple... I can do that.

BTW, is that 4.5" compressed S&S get an air gap or not? What if it's uncompressed (i.e. 6" thick S&S); air gap or no?

[kasmira]

If you want to try it flush against the wall, go for it, but test it with and without the airgap to make sure you're doing your room the most justice.

Good luck on your build, take pics and post them up here!

[avare]

Originally Posted by kasmira

When it comes to absorbers, they should almost always be placed with an airgap. A 4.5" thick bass trap should be placed 4.5" away from the wall. It can increase the frequency range of the absorption by an entire octave this way. However, spacing it away from the wall won't do anything if you construct the trap with a solid wood backing. Make sure you leave the back open (or covered in fabric, w/e) if you plan on moving it away from the wall.

There are so many half truths and fiction in the quote above that the best I can write is to ignore it.

Bluntly,
Andre

[kasmira]

Sorry that I posted incorrect information - just passing along what I've read. I'll try to keep theories to a minimum. Thanks for pointing it out, Andre.

Edited my post.

[darkbuddha]

Originally Posted by avare

There are so many half truths and fiction in the quote above that the best I can write is to ignore it.

Bluntly,
Andre

Andre, I think we appreciate your bluntness more than you know. I'm fairly well educated on the physics, psychoacoustics, and production of sound, but have to admit that my knowledge is limited when it comes to dealing with and controlling the acoustics of a space (a rare privilege for concert music composers!). Ironically, I do spend quite a bit of my time attempting to emulate, manipulate, and transform space in my own music though. The comedy of this is not lost on me.

In any case, I think the suggestion to test with and without a gap seems probably the best idea I've heard today.

BTW...

Originally Posted by kasmira

Sorry that I posted incorrect information - just passing along what I've read. I'll try to keep theories to a minimum. Thanks for pointing it out, Andre.

No worries at all... I find there is value in errant information being posted if it produces worthwhile discussion, ferrets out truth and facts, and teaches. I think many of us could use more knowledge and wisdom on this stuff... that is why we're here, isn't it?

[kasmira]

Originally Posted by darkbuddha

Andre, I think we appreciate your bluntness more than you know. I'm fairly well educated on the physics, psychoacoustics, and production of sound, but have to admit that my knowledge is limited when it comes to dealing with and controlling the acoustics of a space (a rare privilege for concert music composers!). Ironically, I do spend quite a bit of my time attempting to emulate, manipulate, and transform space in my own music though. The comedy of this is not lost on me.

In any case, I think the suggestion to test with and without a gap seems probably the best idea I've heard today.

BTW...

No worries at all... I find there is value in errant information being posted if it produces worthwhile discussion, ferrets out truth and facts, and teaches. I think many of us could use more knowledge and wisdom on this stuff... that is why we're here, isn't it?

Agree'd on all accounts.