Home » Audio » General » Help with my car audio
Help with my car audio [message #25439] Tue, 11 September 2007 14:52 Go to next message
Crystal is currently offline  Crystal
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Registered: May 2009
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If my port is in an "L" shape and i want to change it to a "T" shape do i need to change the dimensions or do I just leave it? Thanks.

Re: Help with my car audio [message #25441 is a reply to message #25439] Wed, 12 September 2007 09:16 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18793
Registered: January 2001
Illuminati (33rd Degree)

This is best tested empirically. The Helmholtz formula assumes a straight, unimpeded port. Deviations from that usually change the resonant frequency somewhat.


Re: Help with my car audio [message #25443 is a reply to message #25441] Wed, 12 September 2007 10:45 Go to previous messageGo to next message
Crystal is currently offline  Crystal
Messages: 110
Registered: May 2009
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Thanks for the response. I appreciate it. And that mkaes a lot of sense.

Re: Help with my car audio [message #25453 is a reply to message #25441] Thu, 04 October 2007 13:34 Go to previous messageGo to next message
Gilipsie is currently offline  Gilipsie
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Registered: May 2009
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Wayne, I got her question but can you put that in "lamons"( I think I spelled that wrong) terms.

Re: Help with my car audio [message #25463 is a reply to message #25453] Mon, 08 October 2007 01:07 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18793
Registered: January 2001
Illuminati (33rd Degree)

Well, in layman's terms, the formula that predicts the frequency a box is tuned for assumes a straight port, not one that is bent or flared or made into a "T" shape. Those kinds of changes are straightforward, and a finite element analysis could surely be done which would give a very accurate frequency prediction. But the Helmholtz formula assumes a straight port, so if you deviate from that too much, the formula will become inaccurate. When making an unusually shaped port, you can always estimate, make the port how long you think it should be and then measure it and modify as needed. Best to make it long at first, that way you can trim it down to size to get the desired frequency.


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