[bpape]

As nice as they can look, for best HT performance, I'd recommend not doing a drop ceiling. You'll get basically zero isolation value from it which will impact the ambient noise level and max dynamic range available. Also budget for a solid core door for the room.

As for treatments, the things that always need to be addressed are:

- Broadband bass control
- Early reflection points on the side walls
- Deadening of the front wall to eliminate reflections from the surround mucking up (technical term there) the front image clarity and lock to the screen.

The key is to get the decay time in the room correct across the entire spectrum. Curtains and foam aren't it - they're high frequency only absorbers, and you already have a LOT of that with carpeting. Consider 2" fiberglass/mineral wool/acoustical cotton on the front wall, minimum 4" (6" or chunk is better) panels straddling the front corners, 2" panels on the side walls for reflections and decay time as required, etc.

Another place to consider is the rear wall with a treatment that will deal with midbass through lower mids but be somewhat reduced in high frequency absorbtion content to deal with the most prominent bass issues in the room from the length dimension.

Bryan