I will be building a box for my Rockford Fosgate P2 12". Rockford recommends ported box volume of 1.79 ft3 tuned to 39hz. I plan on putting the ports outside of the box vertically through the rear deck speaker holes (speakers are removed)

I have been looking for the proper method to calculate what port diameter and length for two ports to reach my desired tuning frequency. Every calculator I have seen is for 1 port.

using the12volt.com it calculates a single round port dimensions as being 4" diameter at 9.51 inches long. What would the measurements be for two ports?

Thanks in advance

 

Nevermind, just as I posted I found the answer to my question

 

where did u find it

 

Ya it would have probably been a good thing to actually post where I found it. Anyways... you can find it at

JL Audio – Car Audio Systems