>>2) The 15' dimension of the room is negotiable. On the other side of the north wall is a 19'x20' gameroom, which my wife is willing to let me "borrow" a couple of feet (along the 19' dimension) from for the media room. Would this help prevent of the problems with certain frequencies?
My first thought would be to stay with something like 15 feet -- that's a nice size for an HT and you want to keep the dimensions "unrelated" as much as possible. It's the length being twice the height which poses the challenge.
>>3) The ceiling is actually about 9' high on the east, west and south walls, and slopes to 10' high a couple of feet into the room along each of these walls.
Oh good. That means the 10' dimension is to the drywall, not to the floor above, so you're really talking closer to 11 feet. Actually -- what do you have above, another floor or attic ?
Assuming your ceiling is drywalled, I would be thinking real hard about asking the builder to leave some openings, stuff 'em full of insulation, then cover with either a wood grill or burlap / speaker cloth.
If the room above is a cold attic and the builder is planning on blowing insulation on top of your drywall ceiling then this would need to be a bit more complicated, of course
>>It's not quite a tray ceiling, though I don't know the exact term for it. Will this affect things any?
Is that what they call a "coffered" ceiling, or would it be more correct to say "there is a soffit all around the room" ? If you want to be overwhelmed with ideas and annoy your family, go to the RealTraps site and look at "soffit traps"
>>4) The back (western) 8'x15' of the room will be raised 1' above the front (eastern) 12'x15' of the room. I assume I'll need to have insulation placed in the 1' riser so that it doesn't cause unintended echoing. Or can I somehow manipulate it to some advantage?
I don't know the answer to this one but it's a very good question. If the raised section is big like this, it can also help by reducing the effective height of the room from 10 feet to 9 feet, IF the construction is solid enough eg. double thickness of heavy plywood and lots of bracing.
>>5) For the speaker wires, I had to ask specifically for 12 AWG wire, or the builder was going to put in 16 AWG wires. Are there different type of RG6 cables, or is that already as specific as it needs to be?
There are different kinds of RG6 but I don't think it matters in this application -- the differences are just related to flexibility vs. signal loss at RF frequencies over long distances.
Builders sure love their 16 ga speaker wire, don't they ? In my house we specified 12 ga, everyone signed off 12 ga, and they STILL ran 16. Fortunately I put all the boxes in the wrong places anyways and am not using the pre-wiring
