This happens intermittantly,but what occurs is I get a hard clipping on channel 29 that causes feedback through the headphones. I'm talking feedback that's loud enough to hear from some distance. At first I thought it was coming from the speakers but when I turned off the mains it was still happening.That's when I discovered it was coming from the headphones. I don't use channel 29. There's nothing that I can find feeding the channel. I've run through all the auxes and matrixes to see if anything from them is clipping the channel but there's no input that I can find to that channel. Then it goes away on it's own. Fortunately,it only has happened at sound check and then seems to stop on it's on. Any thoughts?
