Use of dead air space in bass panel absorbers

[ChrisPrescott]

I have seen several approaches to the bass panel absorber.

The one listed on the SAE shows an attachment of insulation directly to the plywood panel to absorb the low frequency vibrations.

Another design shows leaving an air gap behind the plywood before the insulation as well as additional air gap behind the insulation before the wall. (please see the following site for a diagram of this method. http://www.ethanwiner.com/BTPlans.gif )

My question is basically, which of these is the prefered approach?

Another consideration is that I have left over mineral wool and will be using it for the panel's insulation (not rigid fiberglass boards as is often suggested). So if I need to leave an airgap directly behind the playwood panel, how should I retain the mineral wool so it doesn't touch directly?

Thanks for any suggestions on this topic!!!

cP

 

[Tomi M.]

bump... bump... clicketi-clock... I'd like to know this too...



t0mi

 

[HangDawg]

bumpidy

Me too!

 

[John Sayers]

OK - as I wrote the SAE version I should state how I came to that conclusion.

All that I've read says the insulation should be attached to the back of the plywood panel so it absorbs it's energy when it resonates in sympathy with it's tuned frequency. The thickness of the plywood, the depth from the wall and the tightness of the screws holding down the plywood all determine the resonant frequency.

I'm happy to be corrected on that

cheers
john