Hey guys, I play jazz upright bass in a 18 piece big band at school. I have a plywood bass, an upton bass rev solo pickup, and a markbass players school amp. The pickup is basically a piece of wood that fits in the bridge wing. Yesterday on the wooden stage, I was getting horrible feedback even if I was 6 to 8 feet in front of the amp. I turned the gain down and everything and it just wouldn't stop. I took it to a practice room on a tile floor and it was fine and sounded great. I could be right next to it and no feedback. I need to figure this out, I know there are other posts on feedback but what is it about a stage that could make it do that?