Help Building an Audio Room

Great news!

Congratulations on your listening room.

And you are in the basement.  If you don't already have one, pour a really solid concrete floor slab.  It will ground all your components: turntable if you have one, even CD player, certainly speakers.  You will have an infinite mass below your sensitive kit.  Well...if not infinite, then the mass of the Earth at least.

Then run dedicated power lines direct from the incoming supply and put in a bigger deeper earth post.  This will save you a fortune in mains conditioners and silly expensive power cords.

Then set about your treatment of walls and ceiling others are advising you.

I have a room just like this and down there in the basement half your problems are solved from day one.

Sorry, if you really want to experience what a truly acoustically treated listening room sounds like, you need to get out of the square box. Sorry once again but you will not find any kind of sound nirvana in a square 15 x 15 square room imo.

I have a second system in a 14’ x 13’ bonus room in my basement and I messed with it for several months and it is much better sounding, but still no where the same as the 15’6” x 20’ room upstairs. You need room behind your listening position that I just can’t get in that room unless I move the speakers closer to the wall and then the sound starts to suffer because the speakers are to close to the front wall.

All the best.

I would try to net out a 13X 15 X 9 room. Sound transmission to the master suite indicates using not only a resilient clip system for the ceiling, and a layer of 1/2" plus a layer of 5/8" sheetrock. Fill the joist cavities with rock wool. Make sure there is a 1/4" gap all the way around the ceiling that gets caulked with acoustical sealant. That creates a large, high mass diaphragmatic absorber that will minimize noise transmission upstairs. Also, any penetrations, e.g. lights need to be sealed as well.

For the framed wall, I have had great success with stagger stud construction - 2X4 studs staggered on a 2X6 plate. Use the same dual-layer sheetrock, resilient clips and 1/4" gap as the ceiling.

Have the electrician pull in at least one 20A (preferably 2) dedicated circuits and 2 quad boxes with medical-grade outlets (4-Leviton 8300 series ~$12 each) and add a whole house surge suppressor (your electrician will have a recommendation - budget ~$200 + labor). The total bill for that will be less than an aftermarket device and it will work better.

Carpet and pad are entirely up to you. I tend to favor a commercial grade carpet on a heavy pad to handle the intended traffic. 

Room treatment will make a huge difference. Budget for 6 or 8 2X4 ft 2" fiberglass panels, a couple bass traps and 9 2X2 ft 2" ceiling panels. Actual placement will vary depending on the final room layout . 

Below is my current home theatre / music room incorporating all the elements discussed. The in-wall JBLs, subs, matching surrounds and overheads required substantial active eq to get the sound I wanted, but due to the multi-use nature of the room, I didn't want to give up floor space for speakers. The piano key assemblage on the far wall is a combination absorber/diffuser and has worked very well. You can also see 3 of the 9 ceiling panels. I am very pleased with their performance as well. Bass traps are in the corners behind the seating. All gear except the projector and 110" screen is in a ventilated closet on the right.

The AV is powered by a Marantz 7015. An Adcom 555 powers the subs. I use an Amazon Echo Studio for background listening and to control lighting. 

Hope this gives you some ideas.

@jo1mtb Glad to read that you are finding the AMROC tool useful. The BOLT area calculation is pretty cool. Suggest that you also run the proposed room dimensions through Bob Gold’s tool before you finalize. It is more in-depth and provides a little more complete analysis.

Re: WAF and room treatment/bass absorption, I recently read about a clever idea that might work for you: build a full-width closet at one end of the room (maybe instead of the bookcases?) with louvered bi-fold doors and fill it with acoustic batting material. Sort of a large hidden bass trap. The louvered doors would allow bass waves to enter the chamber while acting as a primitive diffusor for the highs and the interior volume would be pretty large (2’ deep X 15’ wide x 10’ tall = 300 cubic feet), providing effective low frequency absorption and would be completely out of sight and relatively inexpensive compared to standard in-room absorption products.