AppleBonker wrote:MDF sub enclosures don't tend to cost much to manufacture. The eBay box is likely fine. It will probably hit a bit harder than the crutchfield box you linked, but that is due to it being a bandpass box and not a ported box. The bandpass will be louder, but not as clean as the ported box (though a ported box wont be as clean as a sealed box). If you're just looking for volume and not quality, the ebay box might be better. 5/8" MDF is pretty standard, though I think I tend to stick with 3/4".
Bandpass boxes are very touchy. It's better to have a bandpass box custom built around a sub since bandpass boxes only produce specific frequencies. It's essentially a sealed box encased in a ported box. For sound quality bass, you'll want to go with a sealed, but if loudness is what you want to go for, ported/vented is the better box. The ones from crutchfield look kind of flimsy where their interchangeable boxes that can go from sealed to ported don't look like they'd produce quality bass.
Also another tip is to be able to properly tune the box to the sub's specs. Then it'll sound even better. Usually prefab boxes are just given a broad tune spectrum, so overall it might sound good, but if you put in a different sub, it might not sound that great...
I'd check out sound solutions if you want a custom box. You just give them the dimensions and they'll build one exactly how you want it whether it's sealed or ported, single, dual, triple, etc on the number of subs:
http://www.soundsolutionsaudio.com/stor ... re-Design/
I'm probably going to have one custom built for the alpine 12" swx 1243d...I think the manual recommends 1.75 or 1.8" and I'm going to have a 2 cu. ft box built for it.