Re: adding up the ports
To find the length of multi-port set ups, divide the size of the box (in cu') by the number of ports to be used.
You have to count in port displacement. The larger the port is going to be, the larger the box is going to have to be. Also, the bigger around the port is, the longer it has to be. If you port was 6" x 12" you would be at 31Hz in a 5cu' box. Personally I put a slot port in between the subs.
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)