need port sizes
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=28613
Printed Date: July 07, 2025 at 4:58 PM
Topic: need port sizes
Posted By: 97neon
Subject: need port sizes
Date Posted: March 18, 2004 at 3:24 PM
hey guys, i was wondering if anyone knows how long to make the port lengths for a AWT15X, the box is 5 cubic feet, i already have the holes cut, i just don;t know how long to make the ports, i don;t htink it says on the site thanks
Replies:
Posted By: 97neon
Date Posted: March 18, 2004 at 5:12 PM
does anyone know this, it;s for an audiobahn awt15x
Posted By: Ketel22
Date Posted: March 18, 2004 at 6:40 PM
whats the tuning fhz of the subs? or that you want?
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Posted By: 97neon
Date Posted: March 18, 2004 at 7:08 PM
im pretty sure it;s 35
Posted By: DYohn
Date Posted: March 18, 2004 at 7:52 PM
What diameter port are you using? 4"?
Posted By: 97neon
Date Posted: March 18, 2004 at 8:00 PM
2, 4x8's
Posted By: DYohn
Date Posted: March 18, 2004 at 9:17 PM
97neon wrote:
2, 4x8's
Are you trying to say you're using slots? 4" X 8"? That is WAY too large if that's what you are saying. Please clarify.
Posted By: Ketel22
Date Posted: March 18, 2004 at 9:28 PM
i came out with a length of about 19.5 inches for each port. if somebody would plz check that before he starts to build.
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Posted By: Ketel22
Date Posted: March 18, 2004 at 9:30 PM
dyohn, im just wondering what you mean by they are too large? ive used slot ports 6"x24" for an 18" woofer.
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Posted By: 97neon
Date Posted: March 19, 2004 at 6:08 AM
yes, therew square slots on top of the box, 2 of them, and, trust me, there not to large
Posted By: DYohn
Date Posted: March 19, 2004 at 9:55 AM
My calculations are always based on a standard 4" diameter round port (standard for me as that's what I usually use.) At 4". the port needs to be 2.6" long for his 5 CUFT enclosure and a 35Hz tuning frequency. That is 12.56 sqin of port area. His 4X8" opening is 32 sqin of port area. That's why I said it was too large. But, if the openings are already cut, 32 sqin (or about the same as a 6.5" round port) comes out to be 10.3" long.
Posted By: 97neon
Date Posted: March 19, 2004 at 11:36 AM
so i have to make them 10.3 inches lng correct?
Posted By: 97neon
Date Posted: March 19, 2004 at 11:37 AM
why is to big of slots, the specs say to make it that big on that specific sized box
Posted By: DYohn
Date Posted: March 19, 2004 at 11:46 AM
10.3" long. Yes.
Posted By: jbjohn22jb
Date Posted: March 20, 2004 at 5:38 AM
Q: Is it bad to have a port that is too short? A: Although a port is used to get the correct tuning in a box, it is not good to have a ports that are too short. By too short I mean you want the port to be equal to or longer than the depth of you subwoofer. Q: Is there a difference in performance between a circle and a slotted port? A: No, you will get the same performance out of a box and the same tuning frequency aslong as you have the same port opening size and depth. You will need to remember tocalculate the displacement of the thickness of the wood being used as compared to theplastic of the circle ports in the box. Q: How far from the wall of my box does my port need to be? A: You want to have the port the same distance away from the box as the diameter of the port or more.
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