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L-shaped port?

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=82598
Printed Date: April 28, 2024 at 8:49 PM


Topic: L-shaped port?

Posted By: hemanjoyman
Subject: L-shaped port?
Date Posted: September 07, 2006 at 6:22 PM

I'm going to be making a cabinet for my two subs, and I will have to make an L-shaped port. I was wondering if it's ok to make the beginning of the port(the part inside the chamber, not the exit point) wider than the side, which will be the exit point, or is it better to do the opposite of what I just said, or does it matter at all??? If you look a the picture I uploaded, I am talking about the slot width (SW) SW1 and SW1A.posted_image



Replies:

Posted By: stevdart
Date Posted: September 07, 2006 at 9:13 PM
Do us a favor and fill us in on why you want to design the port with different dimensions in each leg.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: hemanjoyman
Date Posted: September 07, 2006 at 9:51 PM
Because of my box dimensions, it just wouldn't work out correctly. I'm just going to decrease the port width by 0.25 inches and it should be ok, and I won't have to make it an L-shape. My box dimensions width = 32.5 inches, depth = 17.5 inches, and height = 14 inches. My port dimensions 12.5 inches tall (3 cubic feet net), 2 inches wide, and 17.5 inches long. But now I will change it to 1.75 inches wide, 15 inches long, and 12.5 inches tall. I'm probably gonna have to change the box dimensions as well, I will figure that out later.




Posted By: stevdart
Date Posted: September 07, 2006 at 10:15 PM

Be sure you can design it so that:

  • you leave at least 3 or 4 inches open into free airspace at the end of the port
  • keep the width-to-heigth ratio of the port better than 1:8 (e.g. 1:4 is better)
  • if you use an L shape, keep the entire port structure the same dimensions

Widen the port opening to make the overall port longer if you end up bending it.  That will keep you out of that tricky situation where you were too close to the back wall to fit another piece of MDF; and it will further decrease any possibility of port noise.  Your sub box dimensions would have to grow a little with that added port displacement.



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: hemanjoyman
Date Posted: September 08, 2006 at 9:55 AM
Yeah, I got it, thanks for the tips. My new cab dimensions are width = 32 inches, depth = 18 inches, and height = 14 inches. My port is now width = 2.25 inches, height = 12.5 inches, and length = 20 inches....ratio of 1:5.6 and best of all, the port is the same width throughout.





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