need expert advice on pvc ports

[94sundance 0]

so i need the calculations needed to figure out my problem(or the answers) with this build want it to be a true not done on a online cal.(unless one will give true port cal within a 2hz of needed frequency) box 20h*48*40*d using 6in PVC? thanks to all that have any input for me. its 4 15s and want to tune between 30 to 34hz.

[94sundance 0]

anybody have any assistance

[altoncustomtech 773]

How many ports?

[94sundance 0]

4

[duanebrow 6]

You have to give more info. How thick is the box going to be? How much space is used by bracing and the subs? A rough estimate is 19-20". I used 12.5 cf as the box size.