How to calculate port length with a bend?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=52234
Printed Date: July 17, 2025 at 8:10 PM

Topic: How to calculate port length with a bend?

Posted By: big_man_tim
Subject: How to calculate port length with a bend?
Date Posted: March 20, 2005 at 4:28 PM

Hey I am wondering how you calculate port length if it has a bend in it. The reason it needs to bend is that the box is behind the seat of a regular cab truck and in order for the port to be the correct length of 3x27.8" or 2x11.9 . The dims of the box are 40.5" wide, 13.5" high, 7.5" top depth and 11.5" bottom depth, with a divider in the center. The box is for 2 JL 10W0 subs.

Any help would be appreciated

Thanks Tim

Replies:

Posted By: DYohn
Date Posted: March 20, 2005 at 5:03 PM

It's a simple linear measurement inside the port. Start at the front and simply measure back to the end (or vice versa ) Be sure to keep the diameter the same all the way. A bend is normal, especially for slot ports. Oh, and don't forget if you have a divided enclosure you need to have a port for each sub and it needs to be calculated for the enclosure volume in each half.

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Posted By: big_man_tim
Date Posted: March 20, 2005 at 6:34 PM

So i Just measure sections A,B,C as shown below and add them up to get the total length posted_image

Posted By: big_man_tim
Date Posted: March 20, 2005 at 6:45 PM

sorry the pic didn't work here is a url https://fordtruckworld.tenmagazines.com/showownerpic.asp?u=14623&n=539261&pos=1&album=32798

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