JBL 4301B

I have a pair of these if i wind the amp and bass up a rasping noise comes from one of the bass units does it mean i need a new unit?

Or a repair..

Basically the coil is a lot of lacquered wire wound around a (hollow) metal centerpiece. There are a few ways for this construction to start rasping in the coil gap: Either, the unit has been driven so hard that the centerpiece has struct against the confinements of its space and has become deformed. Or, it has been driven so hard and long that the lacquer that insulates the coil wires has started to expand. Or, the suspension is a bit worn and simply does not ensure exact positioning of the coil in the gap anymore.

These problems can, to varying degree, be repaired. Clearly the simplest fix is to replace the drive unit altogether. But if the speaker is old and rare, a new driver may be hard to come by. In that case the best thing to do is to stop using the speaker and seek professional guidance before the unit s completely gone.