Rectangular and round ports

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=80283
Printed Date: July 03, 2025 at 11:32 AM

Topic: Rectangular and round ports

Posted By: Flakman
Subject: Rectangular and round ports
Date Posted: July 14, 2006 at 1:08 AM

I understand that you can convert the area of a round port and get the dimensions for a rectangular port. My question is: I've seen a lot of posts saying that the round port should be 3" away from all sides of the box. Why then can the rectangular port run along the side of the box? Why would the 3" rule not apply?

Thanks for humoring me LOL

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The Flakman
I feel strange. I have deja vu and amnesia at the same time.

John | Manteca, CA

Replies:

Posted By: forbidden
Date Posted: July 14, 2006 at 1:27 AM

Makes zero difference as far as I am concerned.

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Top Secret, I can tell you but then my wife will kill me.

Posted By: stevdart
Date Posted: July 14, 2006 at 5:12 AM

Reason: as a safety net against at least these two potential problems -

a plastic or PVC tube extended along the wall could possibly clatter or resonate audibly along its length if touching the side wall, and
the termination of the port tube has to remain some distance from another object (see acoustical port length). The rule of thumb is generally that it be the diameter of the round port.

The biggest difference in the two types being that the slotted port construction is a glued-to-top-and-bottom solid wall, and the PVC port is in free air. The airspace at the terminal end of the port is still needed in all cases.

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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: Velocity Motors
Date Posted: July 14, 2006 at 7:04 AM

Also with the PVC ports I've experienced more port noise than with the rectagular ports. Very annoying if you ask me.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

Posted By: Flakman
Date Posted: July 14, 2006 at 4:04 PM

Port noise is definitely annoying. Should the slotted port be rounded with a router as well? Or would it matter much?

I was thinking about using FG to get the front uniformly painted...the rounded front would look better I think.

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The Flakman
I feel strange. I have deja vu and amnesia at the same time.

John | Manteca, CA

Posted By: Flakman
Date Posted: July 14, 2006 at 11:10 PM

Thanks for all the info on this. When I port my box...it will definitely be slot ported. I was struggling earlier with design in order to make sure that the port would be supported well. The slot port makes things MUCH easier.

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The Flakman
I feel strange. I have deja vu and amnesia at the same time.

John | Manteca, CA