I don't know, 1.1 cu.ft. with 3" round port. 6' seems a little crazy, I don't think it quite works like that. I'm looking into it, but it seems like you can't just tune to any freq. A 3" driver isn't going to hit 20hz...like ever unless it has 6" xmax //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif