Please bear with my ineptitude-- It seems that all bass cabinet and PA speakers have "accordian" speaker surrounds, while hifi/car stereo speakers have foam or rubber surrounds. What's the reason for this? The reason why I'm curious: I am looking for 12" speakers to build a 2X12" cabinet around, and I have found several fairly efficient 12" 4 Ohm car audio speakers that could be possible candidates (they are also inexpensive, a plus for me). None have accordian surrounds. If they can handle the constant bass bombardment of rap music, can't they handle my fairly conservative playing style? Does the surround material affect the sound? I have worked with Theile-Small(sp.) parameters in the past, so I feel pretty comfortable designing a cab around these speakers. Why shouldn't I use hifi or car stereo speakers? Thanks for your patience!