Hello,

I currently have 2 15" q series dual 2 ohm with the b/p option .I'm running these subs in a sealed enclosure and would like to try them in a ported enclosure of 4 cft tuned to 30 hz .However, the FI Audio site doesn't tell you about port length only port area. I was hoping i might be able to receive some help here.

You know that 4 cubic feet won't be large enough for two ported 15's, right? you need at LEAST 5 cubes after all displacement (subs and port), I'd actually suggest 7 cubes. And with the size of the port you'll need to tune to 30 hz with two 15's, you'll probably need at least an 8 gross cubic foot box. Do you have that much room?

They can't tell you length because that's dependent on box size, port area, and tuning. you can find a port calculator somewhere and find out the length you'll need. Just remember that you have to add the port onto the box size you put into the calculator. so if you put 4 cubic feet into the calculator and it gives you a port that takes up 3 cubic feet, your enclosure needs to be 7 cubes total.

I have 12 cft total for the subs