Help Building an Audio Room

Hi All

I have been allotted a 15x15 x 10h room in the corner of my basement by the wife.
While I’m very happy to have a dedicated audio room, I have some questions and concerns. I’m hoping you all might be able to help. 

1) Three of the walls are poured concrete.  The space has crazy slap eco already and the 4th/back wall is not even closed in yet.

I am having the walls framed in, insulated, electrical, drywall etc. I am thinking of having them frame and build one wall an additional distance off the cement wall some amount so the room is not a square

Is that a good idea?  If so, how much out of square does it need to be to benefit from not being 15x15? Is 15x14 enough? Should I go for 15x13?  I can set up the speakers about any way I would like. 

2) Next question.  Should I have them install a certain type of insulation behind the drywall?  Money is an object, but now is my chance to build the room the best way I can within reason and to offset the square room I’m starting with. 

3) Anything else I should consider before/as they begin to frame, etc? 

Thanks very much!


That's probably overkill but maybe you can find a few ideas to incorporate in your new space.

I highly advise not having a square room because of the room nodes you will build into the room automatically by those dimensions.

Do some reading if you have the time on acoustics with room nodes.

15x12 is better than square. Maybe you can go 15x20? The more you can stay away from square the better off you'll be - at least acoustically. You'll still need some bass traps - especially with poured concrete walls.



Pick up a copy of Robert Harley’s Complete Guide to High End Audio. There you will learn why it is so desirable that room dimensions not be multiples of each other. He even shows how to calculate and map room modes. 
Slap echo is a function of unbroken flat parallel walls with little to nothing to do with concrete. You can frame sheet rock over all of it and have the same slap echo. This is handled with diffuser and/or absorption panels. 
The smart move is to build one wall to reduce one dimension to 12 or 13 ft, and use the space behind this wall as a large hidden bass trap. The wall can incorporate storage shelves so it isn’t even wasted space. This wall might even be angled. Mike Lavigne incorporated this exact technique in his exceptionally good acoustic response listening room. 

Whatever you do don’t freak out and overreact. My room when it was bare walls and floor was hideous. Merely adding furniture and components is a huge improvement. 

The good news is the greatest gains are made from the first small steps. Do those few things, get your system in place and listen. There is no substitute and there is no doing it right the first time. Mike paid big pro’s big money and then still came up with even better sound simply by listening and experimenting. 

Thank you both for the level-headed input.  
I love the idea of a bookshelf/built-in wall to effectively build one wall out and provide some trap and diffusion in doing so. I think that will go a long way, and I can see in the pic they did something similar. 
If I did that on a side wall, I might explore building the front or back wall with a bit of angle; top edge of wall built out 6-10” more into the room than the bottom or vice versa. I’m thinking that may help and be barely noticeable. 
The cost is essentially the same to the builders/me, but as I socialized the idea with them a few weeks ago, they said, “That’s a first. Build it out of square?.. We can do that.” 
I’ll check out the book, too. 
Thank you again. 

Good job on getting the harley book. Best single source on audio.

I once had a dedicated room in a basement. It was 13, x 15, after framing the front wall and the right wall. Other walls were framed interior to basement.  I had stand mount speakers along the 13' wall about 2.5" from wall with nothing set in between.  Equipment was on a rack to my right. I had DIY acoustic panels behind speakers, at reflection points and behind listening chair which was ~3' from back wall.ceiling was 8.5'. Listening was nearfield. 

It as like having a front row seat in a club with great acoustics. 

I would frame in the three walls so to approach these dimentions. In the Harley book there is a discussion on best room HxWx L ratios. If you frame in the ceiling to reduce height you should consider adding a sound pannel into it at a reflection point. For that matter acoustic panels could be incorporated into the side and back walls as well.  

Good luck on a great project.  




Even if you do a great job of sound insulating the walls and ceiling, sound travels great through hvac air ducts.  Learned that one the hard way.  Good luck.

@jo1mtb i am also preparing to build a dedicated two channel listening room in my basement with 10 foot ceiling height. I have spent 3 months researching everything from room dimensions for least problematic room modes to optimized wall construction methods for noise isolation/best acoustical performance to best dedicated electrical service practices. 

Here are a few suggestions to consider:

1) Room dimensions have a significant influence on room modes that will give you fits and require big investment in room treatments to try to reduce these “built in” problematic room modes. Bottom line is that a) square rooms are most undesirable, b) any dimension that is a direct multiple of any other creates overlapping axial modes (the most problematic type to treat), c) small changes in any dimension (even a few inches) can have a large effect on resulting room modes.

So, your proposed 15’ x 15’ x 10’ room size is really a big problem (violates a and b above). Even a 15’x 20’ x 10’ room would be a real problem with overlapping axial modes. One of the best ratios is 1.4 x 1.9 x 1. Given our fixed 10’ ceiling height, that would be a 14’ x 19’ x 10’ room. This is the room size I plan to build.

If you want to play with different room dimensions scenarios to see their resulting room mode behavior, try this tool (and also Bob Gold’s calculator):


2) After talking with several big name acoustic design companies, I have chosen ASC. Their technical folks are readily available for consultation (at no fee), are super helpful, and never try to push their products as the solution to every need. I also have concrete block walls on two sides on my planned room space. Their advice here was to build the framed walls at a least a few inches away from the concrete block to give air space for pressure to escape, also using insulation between studs and even plywood sheet on the outer side of the framing.

Since our master bedroom is directly above the planned listening room, sound isolation through the ceiling (both to and from he bedroom) is a major concern. After thoroughly investigating several options, I chose ASC’s ISO-Wall resilient channel system for the construction method for my room. Not only does ASC’s system provide excellent sound isolation, the resilient channel system allows the walls to act as controlled membranes to improve low bass room modes. You can get details on this system form their website or by calling ASC.

3) My conclusion on insulation was that the more expensive types (rock wool, etc) are a poor cost/benefit proposition over standard fiberglass insulation. It is the millions of small fibers with ample air space between them that perform the work on acoustic dampening, so loosely packed fiberglass insulation (R-13:or R-19) works great between the studs in your wall. Consider using 2” x 6”:lumber for wall studs in your construction - much stiffer than standard 2” x 4” studs ad only about 20% more expensive. 

4) As for room acoustical treatment, that is a whole big enigma unto itself. Beware of companies that push “more is better” and “one size fits all” recommendations. Room size and construction have a great deal of impact on how much interior room treatments will be necessary. Poor decisions on room dimensions and construction techniques will cost you much more in subsequent interior room treatments to deal with the undesirable room modes and resonances that will result.

Hope this helps!

Thanks @mesch and @dlcockrum 

I really appreciate the thoughtful input and sharing.  

I'm stuck with the 15x15' max size, and of course I don't want to turn a medium/small room into a small/tiny room. 😁  I'm trying to balance it.  I'll play with the tool and hope i can find something more in the 14.5 x 13.5' space that will work.  Ideally, I don't want to lower the ceiling, but maybe 6-12".  I'll look at what that might do. 

Good to hear about regular insulation.  I will build all walls off the (3) concrete walls w/ 2x6 and add the insulation.  Although, I'm considering building one of the side walls maybe off further, like 12".  Something not equal to the room isn't square.  Also, thinking of tilting the front or rear wall a few inches...likely not noticeable if you're not looking for it.

I can't do anything toooo drastic or the WAF will trump it.  And I get her point.  I don't want to end up with a 5x7' fun-house room.  

This could be good; ASC’s ISO-Wall resilient channel system.  My audio room is below the master en suite.  So, pretty close.  

Thanks again to all!

Probably the best way to deal with room modes is a DBA. Four subs asymmetrically distributed around the room yields such smooth powerful deep bass a lot of the need for traps and such is rendered moot. 

Per the tool, looks like 13x15 x 9H is fairly decent and (barely) within the Bolt Area.  

That might a a good starting place.  To create the 15' wall, just leave as normal.  The 13' wall could be built with bookshelves in most of it. E.g. like the top picture Mr_Slate posted.  

There will be thick pad and carpet on the floor.  Maybe that's a decent start and then, work with sound treatment and furniture and speaker/listening placement.  


you're going to have a big problem cuz the room is square that's the worst kind of room to have so you're going to have to do some major room treatment.

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.

@panzrwagn, I like your 'piano keys' approach on the wall.  A simple 'graphic' approach that makes what's usually bland into appropriate for a audio room....

I think I'll 'steal' that... ;)

Hi, Miller....I'm working towards a distributed sub system, think it'd best with my omnis...time will tell. *G*

Try contacting Matt Clott (spelling) from TAS.  His room is completely done up.  He may have some good suggestions for you and possibly some help in purchasing.


Happy Listening.

@jo1mtb I believe the room LxWxH you are proposing will work well. Check out ATS Acoustics for ideas. The rockwool material can likely be purchased locally and you can incorporate panels into the walls. As oposed to bass traps I placed diagonally in corners. worked well and saves dollars. 

Just as a side note there was an interesting article in the June 2021 Stereophile magazine in the industry update section from Kongens Lyngby of Denmark that quoted studies from Jens Holger Rindel a Danish acoustics software company that the room height was not as critical regarding room nodes as was the relationship of the width to length.  "Any length-to-width ratio in the range of 1.15-1.45 is fine.  So for example if your room is 15' wide, any length between 17.25' and 21.75' is okay.  Surprisingly, as long as the room is wider than it is high, the height of the ceiling doesn't matter very much, Rindel found."  Kind of interesting.

My dedicated room is a little smaller the false wall is a great solution.  I put in fully opening wardrobes along the back wall, packed them with shelves and clothes and dedicated home made base traps. Opening the doors when playing music helps with base control, in fact opening the doors at say 45 degrees also creates a non square room. 


I’ve been watching this thread just to see the advise and approach of others as I built a small listening room 10 years ago (it’s really small). I hadn’t used the tools at Bob Gold’s or other sites at the time but I did hire an acoustic engineer. My space turned out pretty well using the calc on his site- it wasn’t a perfect curve but fairly close to optimal with no bad check marks. I didn’t go into depth with the absorption panels and such but it’s pretty cool! Thanks for the lead to that site- it’s a great resource!


I highly recommend you contact Jeff at hdacoustics. He specializes in smaller rooms and it would be well worth your time to get a design quote. His prices are very reasonable. My room is almost the same size as yours with a shorter ceiling height. He designed my room and I built it and it sounds amazing ! I have some construction pics on my page if you would like to take a look. Good luck !




One other point. I think you can get great sound out of an almost square room. It all depends on how you build it. That’s where the expertise like Jeff has becomes invaluable. My room has no drywall on the inside of the room and I utilize a corner setup. I have no reverb to deal with as all absorption is built into the walls and ceiling. If you are in Colorado you are most welcome to come by and have a listen. 

First of all you can use portable panels to tailor the room regarding the size, the nice thing with portable panels is you can experiment with placement. The auralex panels have two different sides with absorption on one side and diffusion on the other. If you contact the vendors before you buy you can even send them dimensions, diagrams and pics of your room for recommendations :



If you decide to go with on wall treatments this "recipe" worked very well for me. The placement guidelines start at about the :49 minute mark:


Thank you all so much! I really am overwhelmed by the community, ideas, and support on here. You all are awesome!

I’m going to go with 13x15x9 and mobile in-room sound treatment. It’s not a forever home. If it turns out to be a forever home, when the kids launch, I’ll have bigger rooms to chose from at that point. I hope :) ....WAF. 

Thank again so very much!. I got Harley’s book... thick!

Yes a rectangle is better than a square shape for your room.

But what’s better again is no “parallel” walls (no square corners).

Why not make the front wall (speaker wall) 13’ wide and back wall 15’ wide?

Now the the left and right side walls are not parallel to each other which is better still.

It would likely be visually unnoticeable …

Also the resilient channel is invaluable. Please don’t consider skipping it even though it’s a bit pricey, it makes a huge difference in bass response in any room. Or isolation clips which are better still. 

I figured I would check in on this to share some 'results'. 

I ended up having the builders frame the 15x15' room 14x13.5x10h' room and added the sound/fire insulation between the drywall and the poured concrete walls.  Also, there is low-pile carpet (higher than Berber) with a thick pad. The back corner of the room is open about 4' wide into a hallway. Added two medium upholstered chairs. I sat down in the area where I would be listening.  The echo of my voice was very apparent. 

The results: I gave up quickly.  The (slap, I think) echo was so bad, I saw many more dollar signs and an ugly room full of sound treatment.  I've moved my system back up to the main living area.  Much better and no further cost.