# How is End-Correction calculated?

Discussion in 'Archived Threads 2001-2004' started by Isaac C, Sep 22, 2001.

1. ### Isaac C Stunt Coordinator

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Hi,
Calculating end-correction(s) for a simple cylindrical port is quite straight forward -- all that is needed to be known is if the port is flanged/free; in free-air or in a large enclosure.
What about for a cylidrical port which is terminated with flares -- flares with significant flare radius... something like > 2"
Thanks in advance for any information.
Isaac
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2. ### Greg Monfort Supporting Actor

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"Fundamentals of Acoustics", by Kinsler et al., ISBN 0-471-02933-5 is what Dan Wiggins referred me to years ago when I asked the same question, but still haven't followed through with purchasing it yet as his 'rule of thumb' has worked well enough for me the few times I've used it:
"....add the WIDTH of the flare to the length of the port. For instance, assume a straight 1/2" 45 degree chamfer. The overall length of the port should be increased by 1/2", to compensate for the extra "volume" at the terminus of the port. So, if we needed a 7" long port, we'd want a total 7.5" length for the new flared end (note that the extra 1/2" length is actually the flare depth). Thus, you'll still need a 7" piece of pipe, but the "port end to baffle face" will be 7.5" long."
GM
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3. ### Patrick Sun Studio Mogul

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If you went with a flared port kit, they'll tell you to add 1" to the final end-to-end overall port length. In the end, it's not going to "make or break" the sonic quality of the subwoofer if you're off by an inch with the port length.
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