Building a house

- The planning phase is where you determine that ultimate potential that your room will have. Your system will never be any better than the room will allow it to be.
- I've been designing, calibrating and treating systems and rooms for the past 14 years, and it's much easier to work it out on paper/computer than to "fix" it later.
- Proportions are absolutely critical, so figure out the max footprint you have to work with and then work through the various tables that give you best-case scenarios for minimizing standing waves for a room that will fit that footprint. All else being equal, a bigger room is better to a point, as the severity of modal problems tend to be less in a bigger room.
- Ideally, try to acoustically separate the room from the rest of the house if you have anyone to answer to for excessive SPL's - money well-spent on the room versus spending it on a lawyer later. This includes structural isolation and acoustic treatments. If you're doing a slab floor there are ways to isolate and properly treat that. If you'll have a wood-framed floor under the room, be extra careful in the design phase, as a wood floor system becomes a type of passive radiator with a very substantial resonant frequency that can ruin an otherwise great room.
- Pay attention to what the eventual decay time (RT-60) will be in the room - this can be approximated by computer model, and there are guidelines for what's appropriate depending on whether or not you'll be listening to 2-channel music or surround sound A/V.
- Be sure to make the back of the room slightly more acoustically "alive" than the front.
- Expect to balance diffusion/absorption/reflection with room treatments in the final phase - all the computer simulations in the world won't be any replacement for in-room measurements and calibration once the system and furniture are actually in that room.
- Home-run 10ga. feeds to the head-end outlets, ideally from an isolated sub-panel.
- Glass isn't nearly as bad acoustically as one might think, but it does tend to let in a lot of outside noise, so I'd try to minimize the glass and keep it away from the front of the room or the first reflection points.
- And finally, if you can design the room to include infinite baffle subs...do it! I built my home back in PA 24 years ago, and was able to integrate infinite baffle subs into my listening room, and have used them in a world-class ground-up listening room build, and there is nothing like them. Effortless bass down to 10Hz, magnificent harmonic richness that carries up into the midrange, unmatched punch and dynamics. I moved to NM 4 years ago into a house with no IB option, and not a day goes by that I don't miss them. You have to design the room around them, but if you can pull it off, you will be rewarded. Be sure to computer model the room and place them properly in the design phase, as they become part of the structure of the room and can't be moved in the future; putting them in an acoustic null or peak will be a problem that only EQ can minimize, and that will neuter the bass.
- Take your time and get it right now, and you'll enjoy that system forever.
Hope that helps!

Thanks sgreg1 I do use a turntable for substantial listening. Will look into your suggestion.

Thanks audiophilenm, how does one go about computer modeling the room?

Neurop
Building a room as we speak. Couple of thoughts. Get the room dimensions as ideal as practical. Your challenge will always be bass management and keeping your noise away from the rest of the home. High ceiling is preferred. Generally speaking, steel joists are preferred over wood. 24” OC better than 16”.
For not much additional cost, frame room with 8, 10, or even 12” studs and plan to incorporate, integrate, bass traps into the walls, ceiling, floor etc to keep your room open as real estate is expensive. You will thank yourself later on. Bass management is one of most expensive elements to do correctly. Everyone’s advice is spot on from mass loaded vinyl, to double 5/8 gypsum, double walls if possible. Also, your weak link will be your windows. Tuff WAF, but best not to have any, especially at the listening level. Windows with STF’s above 50 will cost you. Door(s), 2 solid core doors separated by an air lock. Affordable. Try and float the floor with a sound absorbing mat, 2 layers of 3/4 ply and some green glue or similar in between if not on concrete. Don’t allow wall and floors to touch. Seperate by 1/8 to 1/4” and fill in with acoustical calk. Plug ALL penetrations (no jokes please), especially outlets with putty pads or similar. More details on line. Best. 

Be careful with the 12 foot ceiling dimension relative to the other two of the rectangular box.  Understand the difference between sound isolation (soundproofing) and acoustics.  Isolation is a science, acoustics an art. Only thing to add about isolation is close up every hole and gap with acoustic sealant and put seals on the door because that’s where the sound will escape. And don’t be surprised if the low frequencies still get out after doing all of the other soundproofing.  Design for flexibility in speaker placement and seating position.  If your room is 12x12x12 change it.  First time post from an architect.