Sub Enclosure Questions

[Unregistered]

I'm building two boxes for two different subwoofers and I have various questions about both types of enclosures(ported and sealed). I need some advice from one of you tech guys (zane?).

Sealed Enclosure:

The enclosure I'm building is to house a 12" sub that needs 1.5 cubic feet of airspace. The dimensions of the box I've come up with to both serve my purpose and enclose the woofer are 13" H, 42" W, 3" D1(top), 7" D2(bottom). Do these outer diminsions give me 1.5 cubic feet (or close to) using 3/4" particle board? What is the formula you use to calculate this?

Also, would stuffing this box with poly-fill make the sub sound better? If not, should I just pad the inside?

Ported Enclosure:

The ported enclosure is to house a sub that requires 1.4 cuft of air space. The port is 3" H x 18.5" W. If the length of the inner chamber is 16.8" deep, how deep should the port be to tune the box to 30hz? What is the formula you use to calculate this?

Finally, I'd like to know the name of a good freeware or shareware program for CAD of boxes.

Thanks!

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[maylar 10+ year member]

There's some free calculators that'll answer your questions at http://www.wssh.net/~wattsup/audio/

Your web browser needs to be Java enabled for the site to work.

 

[Unregistered]

Good luck with the seperate enclosures and different subs. It's a difficult task to get a set up like that to sound good. As for the polyfill, it will make a sub 'think' that it's in a larger box, which increases low frequency response and sub movement. - natem33

 

[Unregistered]

thanks for your posts so far....the site was very informative.

However, the calculator for port length wasn't working, so i still have one question.....what's the formula to calculate the length of a rectangular 18x3" port in a 1.4 cubic ft. box to tune it 30 hz?

by the way, the two different enclosures are for two different cars. i'm building one car for SQ and the other for SPL.