WTB: 6.5" woofer to replace broken woofer in cheap band pass subwoofer
 

3DsoundSurge Review: Boston Acoustic Media Theater

The woofer is 4 ohm. Has a broken surround. I can also probably just replace the surround.

Parts-Express.com sells Speakers, Replacement Speakers, Speaker Building Parts plus HDMI Cables, Home Audio and Video, Pro Audio and Commercial Sound. We offer services for Speaker Reconing, Speaker Refoaming, Speaker Repair. Great selection of Elect has many 6.5" woofers to select from as cheap as $6. Some areretty decent too. Measure all the diameters and hole spacing on the original and use the website above to find an exact fit. Heck at the prices you could buy 2-3 and try different ones for the best sound.

Might try this:

Tang Band W6-1139SI 6-1/2" Subwoofer | Parts-Express.com