I've been going nuts over this with probably too much reading, so I figured it's time to get some outside opinions...
I am currently in the process of adding on to my existing house. Part of it will be a 17x23' basement room for a home theater (going to go with 2.4:1 130" screen, 2 rows of 4, etc). Sound proofing the ceiling is driving me nuts. Basically, I planned on doing a double ceiling (we've already double-framed the walls if there was a load bearing wall), to decouple the theater room. However, building the lower ceiling (using drywall, so it's not a real drop-ceiling) is proving difficult due to space restrictions, HVAC running through the main TGI joists, not wanting to use wire hangars that attach to the main floor, etc.. My question is: should I even do the double ceiling? I know there are some things to be careful of with air gaps and low frequencies. I've attached what I was thinking if we did manage to get the separate ceiling for the theater room working.
I've also thought about just running 3 or 4 layers of 5/8 drywall with green glue and ditching the separate, decoupled ceiling. I'd gain a few inches of headroom too (which isn't a big deal, since we dug out the basement to have a ~9 ft finished ceiling in the basement). I can't seem to figure out what the real STC value would be if we did 3-4 layers of 5/8 drywall + 3 tubes GG per 4x7 sheet, fully insulated between floors with blown-in insulation (most likely Optima), and then hardwood floor above.
As for what is above, it's a game room, and my office. And the floor above that (so it's 3 floors in all...) will be the guest room. Ideally I'd like limited to no sound carrying up to the office, and obviously 0 into the guest room..
I'd appreciate anyone's opinion on this, as I've gotten to the point where it's driving me nuts.