I’m a newbie. I’ve tried to do a lot of research ahead of this posting, but I’m sure I’ve probably missed something –information overload. I'm building a new HT as part of a basement build-out and need some advice. I have reserved a rectangular space in the basement that is 19'(l) x 13.5'(w) x 9'(h) - unfinished. The walls on two sides of the space (the front screen wall and a side wall) will sit in front of cement foundation walls. About 9' of the 13.5' back wall sit in front of another concrete foundation wall and the balance separates the HT from the mechanical room. The remaining side wall (19’) separates the HT from the remaining basement, which when finished will be a rec. room with bar and pool table. This space is directly under the kitchen, which has wood flooring.

I want to make sure that I'm planning the sound isolation and acoustics properly. I’d rather spend the money up front then spend it on a divorce attorney later. I’ve already been down that road once. For sound isolation, I'm planning on the following:

1) The walls the sit in front of foundation walls will be 2x4 construction with RC, fiberglass insulation and double dry wall (1/2 and 5/8) screwed and green glued. They will sit approx 1 inch off the foundation wall, which is wrapped with insulation. There are two small (1'x2') basement windows along the top of the side wall which I plan to wall off. I plan on keeping a small gap (to be chalked with sound chalk) where the wall meets the ceiling and the floor in order to isolate it more.

2) The side wall adjoining the living space will be double 2x4 construction (1" gap), RC on the wall inside the HT, both walls insulated and double dry wall on both sides (different thicknesses, gap at top and bottom, same as above). This wall will have an exterior grade metal door with a weather seal in it. (Unfortunately, it will be located in the front half of the HT, just ahead of the first row of chairs.)

3) The ceiling will be heavily insulated (6"+), 1#/ft mass loaded vinyl, RC double dry wall (similar to walls). I plan on building a 1’ soffit around the outer 3” perimeter so that the recessed lights will not penetrate the ceiling.

4) For the floor, I’m considering either using 2#/ft mass loaded vinyl under the carpet and mat or a floating floor using the pads and two layers of sub-flooring. (I’m strongly leaning toward the mass loaded vinyl route.)

If I’m careful to plug all the cracks, I’m hoping to get a STC over 60. Do you think this will be adequate to keep the noise from reaching the kitchen and/or rec. room? I’m planning on running a Denon AVR-4306 with 7.1 Axiom Epic 80/600 speaker system. I like a true cinema experience (i.e., I tend to crank it up). What am I missing in terms of isolation?

For acoustics, I saw a HT where the four side walls were lined floor to ceiling with 2” mineral wool fiber covered with fabric (for absorption). I probably need to put a panel on the door to stop any first reflections that will occur at that point.

The front of the HT will be a 6” high stage, 3’ deep in front of a 100” screen. I would like to find some way to hide the front speakers and sub. I have seen HTs where the LR front speakers are placed behind black fabric walls that are build at a 30-45 degree angle both sides of the screen. As long as I frame the wall so that the 2x4s are well clear of the speaker fronts (i.e., put by cross support 2x4 at least two feet above the top of my LR speakers) does this create a problem? I would have the speakers in direct contact with the back of the fabric and could even remove the speaker grills. I would also put base traps in the front corners of the HT behind the speakers and fabric walls (any suggestions?). For the center and the sub, I was planning to build a framed-in cabinet (open across the front along the back of the stage just below the screen. It would be covered with black fabric like the fake side walls. Again, I would keep the framing material away from the speaker fronts. I know most hard core audiophiles cringe at the thought of anything being between he speaker and the listener. But would this set-up appreciably reduce the sound quality by any noticeable amount?

Will the mineral wool on all four walls be too much? Should I do something different for the back half of the HT (for diffusion) vs. the front (for absorption)? If so, what would work and keep with my general design?

Thanks for all your comments. Happy Turkey Day!

Bob