The first two comments give good advice, but even better, I think, is this: get F. Alton Everest's Sound Studio Construction on a Budget and his Master Handbook of Acoustics. The latter sounds better but the former is much newer, and better on room-treatment devices. Both tell you how to analysis your room for main resonant nodes, and Master Handbook has a particular suggestion for dimensions. But don't do what I did with a dedicated room: put in a sloping wall-ceiling (cathedral ceiling). Hard to work with! If you want advice on homemade RPG-style diffusors, get in touch with me--but you'll need a table saw to make them. Good luck!
Ideas on building a listening room!!
I am considering adding on to my home a dedicated listening room. All dementions (width, length and height) are adjustable as I have a large area available on my lot. I would appreciate info or direction t to info from anyone who knows about this. Thanks, Ryan