?Depth of bass traps?

[cellardweller]

What variables affect the frequency of effectiveness in building panel (membrane) bass traps like Ethans' design?

1. What affect will different thickness of fiberglass/mineral wool have?

2. What affect will, say a 6 inch depth, have as opposed to the 4 inch depth suggested by Ethan?

I know these answers are somewhere, but I can't for the life of me find them now that I need them!!!

Thanx

[knightfly]

This might help (you'll need to do your own conversions, it's metric)

http://www.mhsoft.nl/helmholtzabsorber.asp

WARNING: Do NOT use the Helmholz calculator at this link - I checked it and it is using the WRONG formula that is all over the net. Instead, use this one if you want to calculate slot absorbers - it requires Excel.

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1363

I checked the calculator in the first link for PANEL resonators, and it's using the correct formula... Steve

[knightfly]

I also emailed the webmaster of the mhsoft site with the correct information - I'll try to remember to check the site in a couple weeks to see if it's been updated... Steve

[Ethan Winer]

CD,

> What affect will different thickness of fiberglass/mineral wool have? <

I honestly don't know. The only way to find out is to build eight traps each way you want to try, and pay a real acoustics lab to test them. If you do that, please let me know what you find out!

> What affect will, say a 6 inch depth, have as opposed to the 4 inch depth suggested by Ethan? <

That makes the center frequency lower.

--Ethan