port length

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=115528
Printed Date: July 14, 2025 at 6:59 PM

Topic: port length

Posted By: absami
Subject: port length
Date Posted: August 08, 2009 at 5:50 AM

when we calculate circular port length for our desired frequency on different sites does that include the thickness of the enclosure which is 0.75?

following are some links to calculate vent length

https://www.the12volt.com/caraudio/boxcalcs.asp

https://www./help/Articles.cfm?id=31

https://www.psp-inc.com/psp-inc.com/c...calculator.cgi

Replies:

Posted By: DYohn
Date Posted: August 08, 2009 at 9:36 AM

If you use the12volt's calculator, you input the material thickness and it does take it into account.

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Posted By: absami
Date Posted: August 08, 2009 at 9:47 AM

DYohn] wrote:

f you use the12volt's calculator, you input the material thickness and it does take it into account.

thats for the cylinder volume calculator.....i am talking about Round Port Length Calculator....the 4th formula....

Posted By: DYohn
Date Posted: August 08, 2009 at 11:35 AM

Well, since you manually enter the enclosure volume, you should enter only net volume for whatever you are building.

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Posted By: absami
Date Posted: August 08, 2009 at 3:45 PM

so if i get a port length of 8 inch for tuning 33 hertz i would add 8 inch + 0.75 wall thickness = 8.75 or 0.75 wal thickness + 7.25 = 8 inches.....get my point?

Posted By: stevdart
Date Posted: August 09, 2009 at 7:51 AM

Got your point. No, you don't add more length to the port because it goes through the baffle from inside to outside of the enclosure. That length, the thickness of the baffle, is part of the calculated port length. In your example above, the port is still 8" no matter how thick you construct the walls. Just don't make them any thicker than 8"!

It will be easier for you once you start thinking of a port as "air" rather than thinking of it as a physical enclosure. While the port is the actual air itself and has its own dimensions and volume, the port structure is the total air / enclosure that is specific for port function and displaces volume from the box.

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Posted By: DYohn
Date Posted: August 09, 2009 at 10:29 AM

Yes, sorry I misunderstood your question. Port length is always the total inside length of the opening from front to back and has nothing to do with how it is constructed.

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Posted By: absami
Date Posted: August 09, 2009 at 1:09 PM

great! thank u so much people....next question coming up in another thread posted_image