Advice on building a dedicated listening room.

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.

You might want to consider adding about 4 or 5 more dedicated lines to your room. Each component should be on it's own dedicated circuits/lines, especially if you have a digital source in the system. At least two of the dedicated lines should be 20amp circuits/lines and the remaining lines should be 15 amp. One 20amp line for the amplifier and the other for future growth (perhaps mono block amplifiers or adding a subwoofer).

I suggest wiring a few more dedicated lines in case you add another component or two into the mix i.e. a subwoofer, dac, tuner, etc.. Since you know what pain it would be to wire it after the room is complete.

You should use either 12 or preferably 10 gauge romex. Look for some good aftermarket romex with 99.95% OFC as it's still very inexpensive.

For dedicated line you may want to consider a 20amp audio or hospital grade electrical outlets at the other end of each line.

And each line should contain no breaks/junction boxes between the service panel and the outlets.

Spend a little more time on the electrical part now or you may be kicking yourself later if you do not.

-IMO

Hello to all. Just wanted to give a quick update, with some observations, on my new room. I'm almost finished, but one negative I would like to pass on is the use of "resilent channel".

After installing the resilent channel on (1) wall (with 1/2" over 1/2 " drywall, with drywall adhesive between panels, and "double wall" construction), I noticed that the wall has a definate "resonance" when pounded with your fist. Also noticed this resonance when I moved a temporary stereo in the room, with lower to mid-bass notes. NOT A GOOD THING!!

The other walls of my room, which are on the "outside" basement concrete walls, but WITHOUT the resilent channel (same 1/2" over 1/2" drywall, same 14" on center studs & "fire boxing" studs) DOES NOT exhibit this same "booom, booom" resonance as the resilent channel-treated wall.

Well, suffice to say, I removed the resilent channels from the rest of my room, and went with 14" on center studs, with 1/2" over 1/2" drywall, and "fire boxing" (at unequal intervals).

Also, if you have ANY type of RF problems (FM station bleed through, etc.) I suspect that the steel resilent channels COULD pose another potential problem, acting as an RF collector (as well as magnetic?)

So, while resilent channel probably DOES do a good job of preventing sound transmission from going through a wall to another ajoining area, it is used mainly in apartment buildings and such, where the sound IN the room is really not the primary consideration.

Since the whole goal here is to end up with a great sounding listening room, I'm afraid I will concede some "bleed through" of sound (sorry honey!) for an overall more solid room SANS resilent channel.

Anyway, I would STRONGLY recommend "testing" resilent channel BEFORE applying to your dedicated room.

BTW, the "Therma-fiber" insulation was pure hell to work with, but is an OUTSTANDING noise blocker/insulator.

Dennis F.