help with port

[UCF52 10+ year member]

i am currently building a box for a 12" JL W6.V1. it will probably end up being used as a compnent sub for home theater. anyways i am using the JL recommended box on the spec sheet (2.25^3 ported). it calls for 2 circular ports that measure 2.5" in diameter and 13.6" in length. well i went to home depot and could only find 3" diameter pvc. my question is, can i use the 3" pvc and reduce the length of the port to match the same port volume as the 2.5" recommended - in this case 9.44" (instead of the 13.6")?? or should i stop being a lazy *** and go to another store and get the proper pvc??

volume 2.5" @ 13.6" = 66.75^3

volume 3" @ 9.44" = 66.73^3

also, why doesnt the spec sheet have the frequency the box is tuned to? can i calculate the frequency of the box?? (i didn't search it yet)

Click to read more...

 

[wu36ca 10+ year member]

Wider port requires more port volume. The port would actually have to be longer than with the reccomended specs. Don't know the equation off the top of my head, but with all the parameters you have you can calculate tuning frequency. With WinISD you can calculate everything you need, but I wouldn't say that program is 100% accurate. Its close enough though.

 

[JohnBlayz142 10+ year member]

Go to http://www.partsexpress.com and buy a couple of aero ports....much better than PVC. Then go to http://www.psp-inc.com and use the port calculator to determine how long your ports will need to be, and build the box slightly larger to accomodate the extra volume.

 

[UCF52 10+ year member]

thanks for your help guys!