calculating subwoofer volume when lining walls

[justinc]

Im trying to design a linkwitz transform subwoofer so I need my internal volumes to be as accurate as possible. Using bassbox software to simulate. Assuming using 1.25" mdf and am going to line all interior surfaces with whispermat2 which is 1.25" thick. should i plug in 2.5" for the wall dimensions, or do you not subtract out the whispermat foam from the interior volume. thanks

[richie00boy]

Is the stuff heavy, bituminous foam, or more lightweight like fibreglass/rockwool?

If it's more like fibreglass treat it like it uses up volume, i.e. like your walls are 2.5 inch thick. But if it was me (and it was like fibreglass) I wouldn't even use it as it will just waste valuable volume for very little - if any - gain.

[justinc]

it is a sound deadening foam, basically really smilar to blackhole5 http://www.silentsource.com/barriers...rmat1and2.html
I have yet to even try it, but I have read others say it is very good for subwoofer enclosures and is much less expensive than blackhole 5.

[Ron E]

A lot of people like to gild the lily. With 1.25" walls, assuming you have used good construction practices, there should be no resonances below 200Hz. Bracing is much more effective than damping at low frequencies. Once you hit the panel resonant frequency, then you need damping.