[bpape]

Don't bother with the Sonotubes. The sand filled thing doesn't work at all - not sure where they ever got that idea but whoever did it, I'd never hire them - they obviously don't understand how things like that are supposed to work. The bass absorbers on Ethan's site operate as a membrane absorber - a completely different principle and very effective - though not broadband.

If you want tube shaped absorbers, get some pipe insulation and fill it with fluffy fiberglass and cap the top and bottom. Just understand that with a tube design, you'll need to be looking at 16" diameter minimum to get into the subwoofer range.

One other suggestion... For the panels on the upper horizontal corners, you'd get a lot of good broadband bass control if you doubled the thickness to 4". In a small room like that, you'll need a proportionately higher amount of bass control.

Good luck,

Bryan