I currently have two Dayton DVC310-88 12" DVC Series Subwoofers purchased from parts-express that were installed in two separate sealed boxes. However, I have recently blown one the woofers. I no longer want two separate sealed boxes and was hoping to modify one of the boxes into a ported box. I then had seen the idea of passive radiators. I was just curious if it is possible to modify the blown woofer into a passive radiator. Any DIY's our there showing this being done? Is it just as easy as removing magnet and voice coil and adding desired weight to end of cone for tuning?

You'd probably get better input posting this in the DIY section.

http://www.avsforum.com/avs-vb/forumdisplay.php?f=155

It's totally do-able. Like you said, removing the magnet, strip the VC off the former, and add your weight. The bad news is you have a 1:1 ratio of PR to driver displacement. Typically, you want a 2:1, meaning 2 PR's for each sub driver. 1 PR can work, but it becomes your weak link.