I wouldn't get too freaked out about the 'to wall or not to wall' question. The more important question, imho, is if you want the room secluded or not? You will not have an authentic HT if it's an open-air affair where room noise can intrude. Same with two channel listening. Will you be bothered by outside influences if you keep the wall open? does that matter to you? What's the purpose of the room, for you alone, mostly or entertaining? If you want seclusion, then build for seclusion. If it doesn't matter, then it's cheaper to build a three wall room than four wall...
I can discern a difference in sound in my HT just when the rear door is open! I prefer the sound of the enclosed room with the door closed.
A lot of sound issues can be worked with by room tuning after the walls are up. Markphd has a pretty good idea about putting up a piece of drywall as an experimental back wall. However, it won't sound anything like that in the end, least of all due to the additional drywall to be added at later date. Moreso, it won't sound great, I'm guessing, if there's no carpet down yet, no furniture, etc. It will probably have more of an echo effect with the back experimental wall in place, and that could throw off your perception in an unrealistic simulation of the finished product.
Regarding the wire, I put the wiring for all surround and the video above the dropped ceiling so that it could be accessed for later replacement if so desired. I made the access from the ceiling into the side walls such that new cables could be pulled. It's not very likely you'll change that wiring often, but you may want to think twice before burying it under drywall ceiling. Your call...
Since you do not have the walls done, you still can save yourself... by finishing your walls in exceptionally soundproof style. I used hat channel (2 leg) on the exterior walls of the room facing the inside of basement. Then I used Homasote (from Home Depot; a sheet compressed paper product for soundproofing) as a first layer prior to drywall. I used 5/8 sheetrock over that. Works fabulously! I ran the screws from the outer later drywall into both the Homasote and the hat channel. The room is like a vault! No sense of hearing room resonance, and that with twin subs!
I would also, if you have the space overhead, consider running the hat channel above on ceiling of room; then use the Homasote as first barrier, especially if there are bedrooms above. In order to have entirely soundproof ceiling (zero gaps) you will need to build recessed sound proof boxes into the joists where the can lights (in order to make this work, you must use mini cans - about 4") will go. make them big enough to have room to maneuver them when you later put up grid and ceiling tile.
Order the hat channel at local Lowes or similar home improvement store at fraction of cost of an audio sound supplier.
Calk very seam and hole. Caulk outlets, etc. Use cable holders to screw the A/V cables to the solid underceiling, so they won't potentially rattle on the grid of the dropped ceiling.
Screw down everything conceivable in the walls when you do drywall. I used approx. 3x the normal amount of drywall screws and screwed into such things as A/C supply duct inside the wall next to the drywall so as to remove any possibility of rattling due to subwoofers.
You have to keep your brain in gear on this project...do not rush it, or you'll potentially regret it.
Yes, this seems excessive, or overkill, but I have an EXCEPTIONALLY quiet room which makes the audio/video experience all the sweeter! WELL worth the extra effort! Cost-wise, it may add another $500-$600 ball park to the project. Most worth it for the super quiet environment in the finished product. If you do it well enough, the room will almost seem like an acoustically separate building.
Remember, going to this extreme will not only save your loved ones from noise (they won't tell you to turn it down!) it will also save YOU from their noise like wallking on the floors above you!
One last thing; if you decide to go this route, with the solid soundproof ceiling under the dropped ceiling, draw out both your electric and A/V cabling schematic a few times to make absolutley sure you're covering everything, and consider upgrading and adding extra cables to future-proof your system as much as possible.
There is plenty more to consider, but this'll get you thinking.
I can discern a difference in sound in my HT just when the rear door is open! I prefer the sound of the enclosed room with the door closed.
A lot of sound issues can be worked with by room tuning after the walls are up. Markphd has a pretty good idea about putting up a piece of drywall as an experimental back wall. However, it won't sound anything like that in the end, least of all due to the additional drywall to be added at later date. Moreso, it won't sound great, I'm guessing, if there's no carpet down yet, no furniture, etc. It will probably have more of an echo effect with the back experimental wall in place, and that could throw off your perception in an unrealistic simulation of the finished product.
Regarding the wire, I put the wiring for all surround and the video above the dropped ceiling so that it could be accessed for later replacement if so desired. I made the access from the ceiling into the side walls such that new cables could be pulled. It's not very likely you'll change that wiring often, but you may want to think twice before burying it under drywall ceiling. Your call...
Since you do not have the walls done, you still can save yourself... by finishing your walls in exceptionally soundproof style. I used hat channel (2 leg) on the exterior walls of the room facing the inside of basement. Then I used Homasote (from Home Depot; a sheet compressed paper product for soundproofing) as a first layer prior to drywall. I used 5/8 sheetrock over that. Works fabulously! I ran the screws from the outer later drywall into both the Homasote and the hat channel. The room is like a vault! No sense of hearing room resonance, and that with twin subs!
I would also, if you have the space overhead, consider running the hat channel above on ceiling of room; then use the Homasote as first barrier, especially if there are bedrooms above. In order to have entirely soundproof ceiling (zero gaps) you will need to build recessed sound proof boxes into the joists where the can lights (in order to make this work, you must use mini cans - about 4") will go. make them big enough to have room to maneuver them when you later put up grid and ceiling tile.
Order the hat channel at local Lowes or similar home improvement store at fraction of cost of an audio sound supplier.
Calk very seam and hole. Caulk outlets, etc. Use cable holders to screw the A/V cables to the solid underceiling, so they won't potentially rattle on the grid of the dropped ceiling.
Screw down everything conceivable in the walls when you do drywall. I used approx. 3x the normal amount of drywall screws and screwed into such things as A/C supply duct inside the wall next to the drywall so as to remove any possibility of rattling due to subwoofers.
You have to keep your brain in gear on this project...do not rush it, or you'll potentially regret it.
Yes, this seems excessive, or overkill, but I have an EXCEPTIONALLY quiet room which makes the audio/video experience all the sweeter! WELL worth the extra effort! Cost-wise, it may add another $500-$600 ball park to the project. Most worth it for the super quiet environment in the finished product. If you do it well enough, the room will almost seem like an acoustically separate building.
Remember, going to this extreme will not only save your loved ones from noise (they won't tell you to turn it down!) it will also save YOU from their noise like wallking on the floors above you!
One last thing; if you decide to go this route, with the solid soundproof ceiling under the dropped ceiling, draw out both your electric and A/V cabling schematic a few times to make absolutley sure you're covering everything, and consider upgrading and adding extra cables to future-proof your system as much as possible.
There is plenty more to consider, but this'll get you thinking.