Recently, I began to hear a popping/crackeling sound comming out of my rear right speaker. Whats wierd tho is that the sound is not affected by the sound of the music. It could be a rattle in my car, but I only recal it when the music is playing. It hasnt occured to me, unitl just now, to turn off my sub and park my car and see if I still hear it. Are these syptomes of a blown tweeter?