I got a question for the stereo gods....If I were to build a ported box for 4 15" subs and the total volume needs to be 10 cubic feet internal diamater and I want the box tuned to around 34 hertz, how do I figure out my port size? And, do I make it one giant port or have two seperate boxes with seperate ports? And do I make a rectangle port or an aero(round) port? Thanks for the help

 

Give me the T/S paramiters for the subs, or at least the make/model of the subs

 

Before you can determine vent length you need to know the area of the vent. For a slot or square vent this is simply the width X hight. You should aim to have around 16^2 inches of port area for each driver, so in your case at least 64^2 inches of port. Once you have this you can figure out the vent length here.

This calculation is only for single vents however, multiple vents require different calculations.