13x24 and loving every minute of it. I have ASC 8 wall panels on each side and 2 traps in front and some help from Acousticsfirst.com on the ceiling. I couldn't be happier and have heard so many sound worse. You need to just block first reflections which you can find with a small mirror and flashlight, and you can also refer to "High End Audio" by Robert Harley or look into PSAudio.com for room tips. Happy listening. :-)