Could someone tell me what sort of material is good to stuff the sub enclosure with? Where can I get it and how much "stuffing" is needed?
Lastly, if the box is currently empty, is it going to make it sound better if I fill it with this stuffing?

Sorry for the amateur question... I haven't had much experience with this.
Thanks.

 

Dacron, available in any fabric store. Lightly stuff the enclosure with it.

 

Here is what I recomend from, crutchfield.com.
polystuffing

 

This link

http://www.win.net/audtatious/audio/fiber.html

used to show the effects of polyfill done by Tom Nussiane (spelling) for Car Audio magazine about 10 years ago.

Basically the larger the box the less the polyfill helps but for smaller boxes it can really help including ported boxes.

For a 1 cubic foot box Tom got almost a 1.25 effective box by stuffing 2lbs per cu. ft. of polyfill. (My memory is a little fuzzy). For a 3 cubic foot box Tom got something like a 10% effective increase by using 2lbs per cubic foot.

So it makes a difference for the smaller boxes. Vance Dickson has done similar tests but didn't get as dramatic of results.

Bear in mind that polyfil might help the box sound bigger but it will to some effect hurt the drivers thermal performance. If you drive your woofers hard for long period, the extra fiber fill is going to hurt heat transfer to some degree.

My advice is to pack the box loose and keep it away from the driver as much as possible.

-Mr. Wigggles

 

Here is a discussion where Nousaine states his case:

http://www.audiobanter.com/q-t_4479-...o-sub-box.html

and his actual numbers here

http://www.diysubwoofers.org/talksho...ages/41415.htm

It appears that he got about a 39% increase for 1.75 cu. ft. That sounds a bit "lofty". (pun intended)

-Mr. Wigggles

 

The material makes the sub "think" it is in a larger box, so if the specs of your sub calls for a larger box than what you can fit, you can put the fill material in to make up the difference. The material, in effect, slows down the sound waves so it takes longer for them to reach the back of the box and bounce back (that is how it makes the sub think it is in a larger box). It is not such a big deal with new subs as they are better designed, have tighter cone tolerances, and more control over the voice coils so the actual size of the boxes can vary quite a bit. The biggest thing you can do is get a sub with a cast frame, the stamped frames are easier to flex which will cause more distortion and a greater chance damage to the voice coil. Ex of new sub tech is infinities new perfect subs have a "phase plug" system that will change the characteristics of the sub so that you can choose from ported, sealed, or even free air systems. If you are really interested, Yamaha wrote THE book on sound reinforcement technology, i will try and find the title. It will tell you more than you would ever want to know about speaker, boxes, etc.

:edit:

Hal Leonard Yamaha Sound Reinforcement Handbook 2nd Edition