Sound dampening material in sealed subwoofer inclosure?

Question

I am getting ready to put a JL audio 12w3 in my car, in a sealed enclosure. Should I put some sort of cotton type material in there? If so where would I get it and why does it need to go in there?

Answer 1

Damping increases subwoofer efficiency by dissipating some energy that affects the sub, particularly the voice coil. It is advisable to put damping material inside a box. Pillow polyfill and fiberglass insulation are common, though polyfill is a lot easier on your skin. Polyfill also "tricks" a sub into thinking it is in a bigger box. Most sealed and vented enclosures require 1/2 lb. of dampening material per cubic foot of enclosure. For best results it is recommended to loosely fill the material throughout the enclosure.

If you disassemble any pro soundstage speaker cabinet, you'll find polyfill.

Here is some info on boxes (and other tips):

http://spkrbox1.spaces.live.com

Answer 2

If the sub enclosure is built to factory specks you shouldn't need to use it at all. But if you built a box, or using a pre-made box that is a little to small for the sub, poly fill will help. It does in a way trick the incloser into sounding bigger but not by much. The best thing to do if you have room, is to match the sub with the box I.E. pay attention to the sub manufacturer's recommended enclosure details. JL audio has a wonderful website with technical detail and instructions (even on discontinued subs.) From memory alone I'm pretty sure JL recommends that the 12W3 needs 1.5 cuft in a sealed enclosure. You will find all kind of conflicting info on the net about running it in a 1.0 cuft enclosure, but stick to JL's recommendations. Also picking a box for what kind of tunes you listen to is a good idea. If you listen to rock, a smaller sealed enclosure will suit you well. it will give you tight, punchy bass with fast return. If you listen to hip-hop/rap a ported enclosure is going to please you more. Although ported boxes are larger, they produce lower freq. This deep bass can be achieved with a sealed encloser but it is hard to find pre-fab ones that will sound as deep as prefab ported or bandpass. If sealed is the way for you, and your using a single 12W3 find or make a box with about 1.75 cuft of volume and do not go below 1.5 unless you are desperate. ps. dont forget to acount for cone displacement!

Answer 3

If it is a quality sub it should have dampening already in it, especially if not a vented or ported enclosure.

Better check to see if you will not void a warranty by modifying. If so, wait until the cab is out of warranty. You may find you don't need to do anything.