Stage and riser on basement slab confusion

Hi guys,

I've searched around and read numerous threads and am still a little confused on what approach to take on this and was hoping someone could clear this up.

I have a 15'10" x 26' theater area in the basement that I plan on putting a false wall in for the screen area to put the speakers behind AT screen and have two rows of seating (back row on riser)

I have M&K S-150's across the front so they will be on shelves or stands. I would also like to put 1 or 2 subs behind the screen wall as well.

Questions:

1) since it's on a concrete slab, do I need to build a stage (for acoustics) with sand or can I just leave the area behind the screen wall concrete? Maybe put 1" linacoustic down? The subs will be on the ground behind the screen wall. Would a stage serve any other purpose other than aesthetics? The screen wall will be your typical GOM wrapped panels.

2) Can I just build shelves into the framework of my screen wall to accommodate the front 3 speakers or would this cause acoustical problems? Roofing felt under them on the shelves? Use stands?

3) regarding the riser - should I put roofing felt or some other material down first? Since it's a slab, is there any reason to raise it up (U boats, hockey pucks, etc). I plan on filling it with insulation as well. I've also read to leave a small gap between the riser and the wall. can all of the frame touch the floor or should I suspend the middle cross boards with hangers? Should I also keep the insulation off the concrete?

Any help would be appreciated!

Thanks,
Phil

Thanks Big. I wouldn't have thought that about concrete. I would have figured it'd be "dead"

to avoid using 100 bags of sand could I just put the subs on mini sand filled platforms?

Also, are there any guidelines for stage height and the corresponding soffit above the stage to have it look aesthetically appealing? My ceiling height is 7'7"

I thought about using the riser as a bass trap but reading into it, it sounded like if not done exactly right, it could do more harm than good.

I am also considering buttkickers but thought it would be easier to just mount them on, or get them built into the chairs themselves. Thoughts?

Also, what's a good all around width for the riser in order to accommodate most reclining theater seats? I haven't picked out the exact ones I want yet.