Tuned to 30Hz would sound nice but for 2 4" ports they would have to be 30.4" long each. You could go with a single 4" port and it would be 13.75" long.
You could slot do a slot port. Something like 13.5" h x 1.5" w and 23" long would get you there. then you have the correction factor (if using the outside wall of the box) that would add an additional .75" onto the length. (This would be on one side of the side that is 15" tall.)
If you built the slot away from the edge you would not need the correction factor. You can also adjust the opening of the port to adjust the length. If volume is a factor, then maybe you would want to go with a smaller size slot that is not using the edge of the box.
Last edited by Trixter; 08-13-2003 at 10:39 AM.
2006 Jeep Liberty
Adire Audio 15" Brahma running off Cadence A7hc, Clarion hu, MB Quart 6.5s and 5.25s running off old school Punch 800a4
146+db @ 38hz with 1200w and a single 15"
Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
*Vb = vol. in cu"
**R = sq.rt. A / Pi (for square/slot port)