Originally Posted by brew

Yes you can use a car sub. You'll need a separate amp. Here is a link to some good cheap plate amps for subs: http://www.partsexpress.com/webpage....up_ID=505&SO=2

Most of those should have no problem with a 4 ohm sub. If you have dual 2, 3 or 4 ohm voicecoils, make sure to wire them in series.