Advice on building a dedicated listening room.

I concur with Bill's statements but for those of us trying to get things done for less check out Rives site it will help you an awful lot www.rivesaudio.com you will learn more in the half hour then you had learnt in your whole life. Of course if you can afford to have them come in and designe your room go for it! Cheers ~Tim

I finished a dedicated listening room in my last house,
which had poured concrete floors and walls. I recommend
framing all walls with 2X4" studs, and using "fire code"
(5/8" thick) sheetrock backed by fiberglass batts between
the studs. I'd also recommend studs on the floor ("sleepers")
secured to the concrete with a power nailer,
and 3/4" plywood screwed to the sleepers forming the floor.
I'd paint Dry-Lock on the concrete walls, and cover the
walls and floor with vinyl sheeting, taped at the joints
to keep the humidity down. I also installed multiple
outlets on three separate 20 amp circuits for the
equipment. Doors should be solid core to prevent
resonant vibrations.

Good listening........... !

Jvogt, nice post. I just did a room very similar in my last house also, including drylock, etc. Did not do the floor s with studding though. What is the reason for studding the floors? (BTW, if you do stud any studs that meet the concrete should be pressure treated water resistant wood, with thin foam insulation meeting concrete under the studs to prevent moisture absorption. Also, I would be hesitant to place vinyl sealing for fear of trapping humidity and the potential of mold growth. Mold is a huge problem in housing today. In fact, I've recently read stories of people having such severe problems they had to tear their homes down. Insurance companies are so terrified of the problem that they are starting to cancel policies and placing homes in a special database when homeowners place claims on water damage (a precursor to mold). Do a google search of this as the Boston Globe has an excellent database online as well as others, I'm sure. Along those same lines, you will still, even with drylock need some dehumidifier system as you will not be able to eliminate moisture in a basement completely.
I had a dehumidifier and ran it intermittently which helped keep it very dry and comfortable. A

Also, I found that my sealed, double blueboarded, highly insulated room became VERY warm. I solved this with a split system A/C unit, which is the best way to go since it is the quietest ( I tried Mitsubishi which was a little too loud. You may want to check out the Sanyo's which I believe are the quietest) Your condenser is outside, and you only have a 3/4 inch pipe to run into your listening room. Also, because you're in a basement, for comfort/health I would suggest an ERV fresh air exchange unit, which will bring in fresh air from outside and if like me you live in a cold clime, recycle some of the heated air with cold, fresh air from outside. This also helps deal with the mold/moisture issue.

I have built two rooms and have had very good results at minimum expense (of course I did most of the labor myself). Room dimensions are very very important and you want to try and get close to the ideal. Elgordo's advice above is good as you are looking for a basic shoebox shape. Both of the rooms I've done have at least some concrete walls and a concrete foundation. The current room is mostly 2x4 construction with the exterior walls that are not concrete being 2x6. The ceiling height is 8 feet but is broken up with the main heat register running through the center. I did a very solid 2x4 construction around this and stair stepped the sides. I was not happy about the register, but in the end feel it probably does more good than harm, and the stair step is a nice visual detail. All walls and ceiling are insulated with fiberglass and I ran four circuits into the room; 2 for analog, 1 for digital, and 1 for lights. Rather than use 5/8 inch drywall I used two layers of ½ inch glued together with construction adhesive. In both of the rooms I’ve done I used resilient channel for soundproofing. This is a Z shaped metal channel that you screw to your studs, which allows your drywall to stand ½ inch off the studs. You screw the drywall into the resilient channel rather than the studs. You can get this from any drywall supplier that specializes in drywall. Probably the most important thing is to use more than one layer of drywall. I used ½ inch rather than 5/8 inch because it is so much easier to handle and I hung my own drywall. If you’re paying a drywall crew I’d go for 5/8. The more the better. The whole idea is to have really solid walls. One inch works really well, but more can only be better. I know of at least two rooms that were done with three layers of 5/8 and then plastered. I think I would do this rather than ASC Wall Damp if you have the budget and plan to keep your house. You will be astounded at what the right dimensions and one inch of drywall and proper insulation will do for your sound. I am always amazed to see photos on this site of really expensive gear in really awful rooms with obviously bad set-up. If you’re serious about achieving good sound the room is where you should start. It is money well spent even if it means spending less on your gear. Take your time and do it right and I’m sure you’ll agree it was worth the effort and expense.

Great suggestions so far -- I'll second the motion on reading Everest's book. Your limiting dimensional factor is your ceiling height* so I would not recommend making that any shorter than you need to do. Therefore, the raised floor might not be ideal (use carpets or rugs). There are different approaches to the ceiling. All of them would involve acoustical insulation between the joists. One option would be to use the doubled up drywall (per Tswhitsel) and hat channel construction with acoustical treatment of some type over it. Another option would be to hang acoustical tiles (the advantage of that is the direct physical contact to the joists is only though the wire). Do tons of homework or hire some professional help. But I wanted to reinforce how important it is to keep as much of that 9 foot acoustical height as possible. Good luck.

Footnote
* If you take golden ratio approach of the 1.618 factor (i.e., the width should be height times 1.618 and the length should be width times 1.618) a 9 foot ceiling would require a 14 foot six and three quarter inch width and a 23 foot six and three quarter inch length. The longer the length, the lower the wavelength the room can accommodate without creating a pressure zone (generally, pressure zones create inaccurately high bass -- you are, in essense, inside a speaker). A length of 23' 6 3/4" yield a pressure zone area below 16 Hz (3 times the wavelength of the rooms longest dimension): That's good. Where pressure zones end, standing wave areas begin. The standing wave frequency range for the 23+ foot length goes from 16 to 144 Hz. This is the strongest region of standing waves and will result in some dead spots and artificially boosted spots in the room (add at least an octave, maybe two to get to the overall range of influence). The longer the room, the better the sound (given the same ratios). The shorter the ceiling, the shorter the length should be. So keep your ceiling as tall as you can. The good news is that a 9 foot ceiling allows you to do the studs and double drywall on the walls as suggested by Tswhitsel (you should probably need to use 2x2 studs rather than 2x4 though).

The 1.618 ratio is not magic. The math can be found in Everst's book -- please read it. This stuff gets real complicated real fast. You also need to consider reflection times, etc. Send me an email and I'll respond with more info. Here is the scary part -- I'm not even close to being an expert even after doing tons of research. The good news is that even a little research will yield better results than doing nothing.

Look up "acoustical treatment" and "dedicated" on the forum search function to learn more about treatments, dedicated rooms and dedicated lines. Good luck.