what exactly does a blown speaker sound like??? right now im playing through a fender cab with an 18 inch black widow, and two 12"s above it. ( the 12's arent working, dont know why) but to the point, it sounds very bad and distorted, i was told it could of been the " board " or whatever sort of circutry is inside of it. is it blown? or could it in fact be the 'board' ?