more often than not, it is a wallboard or other lose item near the sub that's making the sound. you might try moving the sub away from that wall and playing at the same volume to see if the rattle goes away or is obviously coming from somewhere else. at moderate volume the sub wouldn't rattle...
more often than not, it is a wallboard or other lose item near the sub that's making the sound. you might try moving the sub away from that wall and playing at the same volume to see if the rattle goes away or is obviously coming from somewhere else. at moderate volume the sub wouldn't rattle...