View Full Version : Converting Sealed Box -> Ported Box?

03-18-2006, 10:28 PM
Well I have a Powerbass XS 12" sub running off of a Directed 1100D at 2 ohms (800wrms). The box is sealed with a volume of 1.8 net cubes.

I'm looking for a little more output, so the question is, could I add a port (PVC or aero) and some polyfill and be set? I've fiberglassed the bottom of the enclosure, so rebuilding is not an option, I'll either port it if I can, or leave it sealed if I can't.

The box is already a little big for a sealed box. The recommended ported enclosure is 2.0 gross cubes (exactly what I have now) tuned to 37 hz. It calls for two 3" x 13" circular ports. The problem with this is, my box is only 9" deep (I'd like to face the ports upward, the box is in a hatchback). Is there any way I could add more ports or increase the diameter of the ports to decrease the length of them?

Please let me know of any suggestions you guys have!

03-18-2006, 10:32 PM
didnt u already start this thread? urprolly gonna have to add ports to externally with that volume

03-18-2006, 10:46 PM
The volume isn't the problem, its the depth.

03-19-2006, 11:47 AM
the ideal recommendations for the sub in a sealed enclosure is 1.25cu'. for ported it is 2.5cu' w/ 20sq" of port X 14" long for a slot port and 2 3" ports X 10" long for round ports. this will get you tuned to just under 38hz...like 37.7hz.

i would not recommend using that box. form expierence, these subs love box ported boxes.

03-19-2006, 01:11 PM
I'm looking at the manual in front of me right now. It says for a "small ported box" it recommends 2.0 gross internal cubic feet with 2 13" x 3" circular ports for a tuning of 37 hz.

I don't see why they would recommend this box if it doesn't sound good...

03-19-2006, 01:31 PM
yep your right..i was looking at the one for the "optimum ported box"..

these may help ya...



03-19-2006, 01:43 PM
since your almost there i get 14.25" long for your ports...to get shorter ports, you'll need to go with smaller diameter ports, which would be less port area, which would be less desirable. you could split the difference and have some of the port outside the box and some inside. remember, if you go with a 3" port you need to stay at least 3" from the rear port wall...go ahead with these ports and have the difference stick out. in that case, i would go with the 13 or even like 12.5 to make up the displacement difference of the port that is not in the box....since your box will be a little larger

03-19-2006, 02:38 PM
90* elbows always work... jsut a lil tip ;)

03-19-2006, 06:58 PM
90* elbows always work... jsut a lil tip ;)
You're a genius! How do you calculate the length of the elbow?

03-19-2006, 08:07 PM
just measure down the center.

03-19-2006, 09:09 PM
eh i have a better method i think but hard to explain. 100% accurate

03-19-2006, 09:14 PM
a 4 inch 90* elbow from homedepot is right at 12 inches down the middle.

03-19-2006, 09:32 PM
eh i have a better method i think but hard to explain. 100% accurate
Awesome! Thanks for all the help, man.

Problem solved - thanks all for your help!