Most major speaker manufacturers supply recone kits for their speakers, but there's a technique on how to do it that you have to know before you begin.
Here's a great video that not only shows how a JBL 2226 woofer is reconed, but gives you a great inside look at the different speaker parts as well.
If you want to try recone a speaker yourself, you can get the replacement parts from simplyspeakers.com, who made the video below.
