Anyone know of a source for long-fiber wool?

You can pick long fiber wool up on eBay, there are quite a few vendors that sell washed raw sheep wool in various weights. I just picked some up the other day.

Hippie Sheep!

Thanks Geoff!

Don't forget about the moth problem:( http://www.wikihow.com/Keep-Wool-Clothing-Safe-From-Moths ). If you are going to use is as damping, in an open system or building a transmission line; bonded dacron(polyester fiberfill) works great, and doesn't need to be treated. ie:( http://www.foambymail.com/DACRON/polyester-fiberfill.html ) ( http://www.ebay.com/itm/NEW-Bonded-Dacron-3-4-oz-54-inch-wide-by-the-YARD-/230609037713 )

Didn't realize there was a moth problem, but this is for a sealed midrange.

Won't be a problem then. They need a way in!

The trick is not to use very much wool at all. It is certainly not a good idea to stuff the thing as that only stifles the sound.

You can use whatever is leftover for a sweater.

Geoff, yes indeed, that's what has kicked off my experimentation with it. The manufacturer originally overstuffed it with just plain ol'e fiberglass....yuk. The enclosure is a simple cylinder made of thick sonotube with a flat square of 3/4" mdf glued to the back - so there were reflection problems the manufacturer had not bothered to mitigate before just cramming it full of fiberglass and calling it a day. But, trying to reduce the amount of fiberglass just resulted in more harshness along with the increased liveliness. Took an assortment of a few different sizes of wooden dowel caps and glued them in a spaced pattern on the rear mdf and the flat back of the midrange driver. That seemed to help scatter some of the reflection. Then I cut a 3/16"-thick divider pannel to slide down the length of the tube to help with columnar reflections a bit, which did seem to sound just a tad smoother. With all this I had tried varying amounts of polyfill, which, while more promising than the fg, was still just a bit on the harsh sounding side. On impulse I stopped in today at a Micheal's (an arts and crafts chain store) and happened to find a few small bags of what they call "roving wool" - wool that's been processed, but not yet spun into yarn. Trying it now and it seems to sound much smoother than the polyfill...which will likely let me dial in the right amount of liveliness-vs-smoothness for my current equipment and room choices and what have you. And I can keep the leftover wool should I ever need to reassess or if I change the setup in some way.