acoustical plan - suggestions wanted

[philmadxx]

I have a plan, I just don't know if it is a good one. Most of my decisions were based on what I gather from here and other places on the web.

A little background:

My dedicated basement HT is 14'5"w x 24'8"l x 8'h, there is a riser (2 layers 3/4" ply stuffed with glass) in the back for the second row of seats. Construction is double stud, double 5/8 drywall walls on interior - single 5/8 on 2 exterior (poured walls). Ceiling is 2x 5/8 hanging on RISC clips. Thick padding and carpet on the concrete floor. There is a 48" HVAC bulkhead I have soffits around the perimeter - 13" w x 7"h. The sides are drywall, the bottom is open.

Electronics:

7.1 systems with Onkyo SR 855 (?) driving AV123 850 Rockets and bigfoot in the front, rocket dipoles on the sides and rocket bookshelves in the back. I will have two subs, MFW-15s for now until I build my own. Wiring is everywhere, I planned to have one sub in the front and one in the back, centered on the walls. Panny AE-1000 set up for anamorphic projection, 115" widescreen (TBD), bluray, Direct TV HD are the sources - haven't bought into the HTPC....yet.

The plan:

I was going to install OC 703 in the soffits for bass trapping. I can get it to be 6" x 13" with GOM over it. There will be about 96 lf of this "bulkhead" total around the room.
I also plan deaden the back wall with 2" OC 703, tri traps in the rear corners, 1" on the front wall, first reflection points for both rows, nothing on the ceiling.

Questions:

Do I have a good start for acoustics?

Will the soffits be enough bass trapping?

Do I need something on the ceiling?


I have a CAD file almost done that I think I can change into a suitable-to-post format as well as some pics when I can post them.

Thanks in advance for all of your help!!

Phil

[bpape]

Hi Phil

In the soffit as designed, I'd likely use paper faced wall insulation with the paper exposed to the room to minimize overdeadening the upper mids and highs but still get good bass control. This will also save you a ton of money over 703. Once you get to about 6" and you already have the other things, the density difference doesn't matter so much.

I'd likely use 2" on the front wall.

On the rear, 2" 703 is good. I'd use an FSK facing on this to keep the surround field lively but still get the bottom end control/null control.

If you're just doing visible panels on the side walls, I'd plan on at least 4 2'x4' panels on each side. 2" thick if you can tolerate it.

Bryan

[philmadxx]

Thanks Bryan - I was hoping you'd chime in. If I can get away with the standard insulation with a kraft facing in the bulkheads, that saves me a lot of work and money. Is there any advantage to stuffing it and compressing the 'glass?

The 2" on the front wall surprises me, is this for high frequencies? Will the screen affect this, it will be about 48"h x 125"l?

[bpape]

2" on the front wall is more to help with boundary effects (SBIR). If you can do something behind the screen, that would be great.

In the soffit, you can compress a little if you want. I wouldn't get carried away as you're not really doing much except spending more time and money.