Sealed Enclosures

Alright, for the past few days I've been working on a subwoofer housing. I'm using a JBL car audio subwoofer. The specs that came with the speaker said that a 1.25 cubic foot enclosure was adequet for a sealed enclosure. Now, I've put it in the box with all the gaps sealed and sanded, but eventhough I've turned down the treble all the way and the bass all the way up, the speaker still sounds like it is out of the box. I tried to fill it with fiberfill, and that helped a little, but the treble is still eminating from the speaker. Also I've noticed that the box itself vibrates a lot when a bass sound comes along.

Can anyone please help?

construction materials: plywood(top, bottom, left, right panels) and mdf(front and back)

No bracing, would that help? I assume crossbraces running either opposite walls or lining a panel would work well.

No crossover. It's a subwoofer purchased from circuit city...I know...but it's worked alright when it was hooked into my car sound system.
you should use a crossover if yuo want it to be a subwoofer or your going to hear the voices clearly and nothear the maxumum performance of the sub because it is trying to play all the frequancys that are forced through it..

get a electronic one or look at your amp that your using ( if in a car it should have a x-0ver built ito the amp..



diyAudio Moderator Emeritus
2002-01-19 9:25 am

So having a lot of bass is just about as good as having a lot of sex.
I just realized that your expectation of bass and my expectation of bass are probably different. That said, I'll continue on anyway and let you sort out what might be useful to you.

The baffle is the "side" (front, back, top, or bottom) that the speaker is mounted on.

3/4" plywood will work and should not flex much in such a small box. The 1/2" MDF is starting to be a little thin, and may be adding a little bit to your problem.

Bracing should be used. The lack of bracing is not helping your situation either.

That said, you should still be able to get a "fair" level of bass from your speaker. Now "fair" has to be qualified. By "fair", I don't enough bass to blur the vision of you car in the mirror of the car in front of you, but enough to feel it in your gut when played at high levels.

So, what’s wrong? Maybe the box walls are too thin as you say they are vibrating. Bracing will help here. If your using a gasket between the speaker and the box, make sure the speaker frame is not twisted and that its mounted solidly to the baffle.

Lastly, (Do this first) go over to Radio Shack and pick up a book on speaker building. If you feel committed enough, you find the “Loudspeaker Cookbook” by Vance Dickerson.

But, by all means, have fun.
Rodd Yamas***a