Help Building an Audio Room

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.

yes making the room rectangle  will be a lot better than Square.