Ceiling tiles using rigid fiberglass

So, you are looking for a whole ceiling of absorption? Or is the goal to "soundproof" the room from the upstairs? I am certainly no expert but I have been messing around with my own diy rigid fiberglass creations for a while and I think that the whole ceiling covered in 705 would sound awful. In this application, I don't know for sure, but these panels can be VERY effective at sucking the life out of your stereo..... I don't know how else to put it. If it were me, starting over, I would drywall it and then mess with placement for a while of panels on the ceiling, mark out the spots you think sound the best for the traps and then finish (i.e. paint, spackle) and finally permanently attach your panels.

There is a lot more proper acoustics than just absorption (diffusion) and you would be well served to do a lot of research before going off the deep end..... Just my opinion.

I agree with Hessec. Too much absorption will suck the life out of the music. I experienced that back in the early 90s using anechoic foam panels. (We had leftovers from our NVH chamber that we built at work). Drywall the ceiling. Use insulation to isolate the music from the upstairs area, if you want. Treat the corners and upper middle ceiling to wall interface with sound absorption. Just vary the amount of treatment to acheive what you want. Low frequency sound waves are very long and require deep insulation (>1 foot) to be absorbed. Thin panels will mostly absorb high frequencies. Corner treatment cuts down mid-low frequency reflections which makes the bass sound clearer. That is my experience.

Tonywinsc has given you a wonderful and easy to follow tutorial!

may i add that the corner treatments [or traps] will also go above 100hz to deal with time smear on the mids... A bonus if you will...:-)

Good luck and look up MSR "clouds" for your ceiling!

If you are indeed looking for better soundproofing between the two floors, I'd recommend using something like Quietrock 530 or Soundbreak XP. Standard drywall solutions leave quite a bit to be desired as far as STC ratings are concerned. I used both products in constructing my new sound room, and the differences are not subtle. Combined with an insulating product such as Roxul Safe N' Sound, you significantly decrease sound transmission without resorting to more expensive framing solutions (staggered stud, double walls, etc - although these add yet more isolation for excellent STC ratings). Have fun, and remember the work will be worth it in the end!

Cathode, I'm making twelve 2'x4' 2" panels using Johns Manville 817 rigid fiberglass panels http://www.jm.com/insulation/performance_materials/products/ci9_800series_spin-glas.pdf

I considered Corning 705 but sound absorption coefficient at 125Hz is only 0.16 (almost not working) while Johns Manville 817 is 0.38 - much better. 125Hz absorption is important to me on the walls but I'm not sure if it applies to ceiling. I had an option to go to 4" panels (much better at low frequencies) but there is WAF.

Maybe you could "tune" your ceiling by mixing in some solid panels with the fiberglass ones. You could rearrange them until you find a balance. Just a thought...

Currently open joists?

Here's an unusual method, and I admit I've never tried it on a ceiling. Insulate as usual between the joists but be careful that the insulation stays above the bottom of the joists. Another vote for "Safe and Sound", being far cheaper than rigid fiberglass and far better than soft fiberglass. With 1"X 2" make a lattice of 4' squares under the joists and screw 1/4" hardboard to that but only to/through the lattice. Doesn't have to be precisely 4' squares. Take advantage of the joist spacing and cut the panels accordingly. Use lots of screws, like every 2 or 3". You don't want rattle. The gaps can be puttied up, sanded and painted. Saying hardboard over drywall because I wouldn't want to see drywall fall down but drywall is more fire resistant. Full 4'X8' could sag but that doesn't mean you can't screw down the center of 4X8 sheets. Actually, maybe go 4'X2' lattice although that does reduce effectiveness.

The more rigid and thick the membrane, the larger area (lattice) it needs to vibrate but that also means that it can "absorb" lower frequency. Drywall can be used as a membrane but not over a small area when mounted rigidly. There are flexible mounting tricks but nothing I would advise for a ceiling.

To ensure nothing falls down on the membrane and potentially rattles or impairs vibration, any kind of mesh/screen/open fabric barrier can be stapled to the joists before the lattice. Plastic wouldn't breathe and paper not much better.

Essentially the entire ceiling becomes a membrane trap that would be effective for mid to upper bass while not sucking out high frequency. It's a narrow band trap while soft traps are wide band. The membrane works by converting movement to heat but more effective with a acoustically damped chamber, which would be the joist space. The depth of the joists helps too. Some say the ideal chamber should be airtight but, on this scale, be practical.

http://www.realtraps.com/modecalc.htm

The link above might help predict your room behavior.