....coming from somewhere. Crap. Check my cab, nothing is on it, nothing's on the amp. Cables are all fine. Guitar player checks all his gear, his pedalboard, his channels. Nothing. No rattle. We go to play another song, and the rattle returns. More checking, more testing. Nada. Song #3, and the rattle takes up most of the vocals. Check the mic cable, the mic, the mic stand....and then.... I had a plastic cup of Coke in the drink holder on my mic stand. The rattle was the ice rattling around inside the cup, being picked up by the mic. Shure SM58's. They pick up everything!