Ive got a 98' svt-cl with the ampeg 8x10. I play a 72' gibson eb-3 and a shecter model T. I tune down to drop C. I just had my head gone over and retubed (power tubes) since I bought it. Lately im noticing a lot of crackly buzz coming out of all the speakers when I hit my low C string. Sometimes it buzzes and sometimes it doesnt. Its not fet rattle. Ive seen other bands play in C with the same gear and it sounds bitchin. It almost appears to go away if I play for a few minutes. Then I switch to standby, turn it back on and it does it again. Help.......was my amp guy not thorough enough? I didnt notice this b4 my amp was setup, nor did I notice it immediately after.