'Home' subs have voice coils also. From what you've described, it sounds like ya blew it. If you have access to another speaker, plug it in to the same connection and see if it has a similar noise.
I blew two different Cerwin Vega 12's and the estimate to repair them was damn near as much as new ones.
+1 switch speakers if you can. if you can't dont waste your money fixing it, buy a new one