looking for formula

looking for formula on calculating dual ports for a sub box. anyone know it or a site where i might find it.gcorrea

Calculating what about the ports exactly?Certified Security Specialist

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tuning  frequency, if i use a single 4 inch port my port will be about 25 to 30 inches long to achive my desired frequency and since the front of my box is about 14 inches from the back i figured i can use dual 4 inch ports. insted of getting a  90 degree elbow for the pvc and running them through the box.gcorrea

It is not as simple as you make it sound. Using 2 ports will actually make both ports longer. Lets say you are using a JL 10W0-12 in a 2 cubic ft box, with 2 subs, tuning to 45hz. If you use 1 4" port it will need to be 5.47" long. If you use 2 4" ports then both will need to be 13.88" long. If for some reason you used three then all ports would need to be 22.29" long. This type of calculation needs to be done with a box building calc or program. I could probably dig up the formulas, but there are bunch of them and it is just easier to use WinISD or like.Certified Security Specialist

Always check info with a digital multimeter.

I promise to be good.

Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.