Use at least double that, or port noise will rear it's ugly head. The TC9s are really nice woofers. Supposed to have great SQ and good output with the right enclosure. I actually have a TC9, but haven't got a chance to use it, and now that I'm trading it, I won't:crap: . For more info on what you can expect, try a search on the RL-p, since it's a TC9-based woofer.i have a question... every tc driver i have seen for the box specs seems to have a very small port. they say to use 12.5 square inches or port for the 12" tc9. the 10" i have i'm using 22 square inches of port. why do they want such little port area?