Originally Posted by avare
Sheesh, you are using a model from John's site but are posting questions here?
Yes keep the holes with the gap if you wish.
In future do some product research before wasting your money. You could have filled the space with Safe N Sound, spent less, and if anything gotten better acoustic performance.
I'm posting questions here, because I've posted multiple questions over at the JS forum, and no one has answered me.
I did my research on acoustic materials, but Safe-N-Sound was not available anywhere in my area that I could find. The RHT40 was only $1.10 sq/ft, and from the specs I've seen, is nearly equivalent to OC703 in absorption coefficients (being better than 703 in the 125Hz range, which is where my room needs most of its treatment).
Originally Posted by kasmira
Yes, leaving a gap is usually suggested. It will increase the effectiveness of the absorber to go a bit lower in frequency. It would be even better though to use just straight mineral wool. In other words, 8" of the Roxul will absorb more than 4" Roxul + a 4" airgap. But, the airgap will still be great for all the 4" thick panels you create. The holes on the sides of the frames serve a couple different purposes. The holes don't really change how the absorber works, but instead, it makes the frame much lighter, and leaves more mineral wool exposed (meaning more absorption). You do not need to extend the wood frames an extra 4" for the gap or anything, you can just put a couple legs on the back to keep it 4" off the wall and you will be good. But, it would look cool if you did :P
Superchunks aren't necessary, but they do work great so I do recommend them. Obviously, buying Roxul RHT is probably not the most bang for your buck for superchunks though; I would probably suggest making them out of plain, uncompressed, unfaced R30 (9.5" thick pink fluffy attic insulation) - however, straddling corners with the roxul board will still do a good job as well.
With 15 batts of the Roxul I would definitely suggest making a couple 8" thick panels (just double up the boards). And also, with that many boards, it'd be nice if you could make the ones in your corners the full height from floor to ceiling, although I'm not sure if that would necessarily be the best place for them.
Thanks for the heads up!
I was actually planning on doing the frame the full 8", just because I like how it looks. If putting the holes on the extra 4" of the frame is fine, then I'll go ahead and do that, because I think it looks pretty awesome
Interesting suggestion on the R30 for superchunks. I might have to look into that, as I'm sure it's going to be a much cheaper alternative, and I should be able to get wholesale pricing on that, as my dad owns his own construction company - I could order through his company.
I was planning on doing the corner traps the full height of the room (well, probably a few inches shorter, since I want to be able to remove them easily if I ever move to a different room. I'll definitely try a few 8" panels, especially since I should have some left overs.