I turned on my rig and got a high-pitched squeal. Here's the signal chain. Yamaha active bass, pedal board powered by a Voodoo Labs power supply, head, cab. I started trying to eliminate things, and I changed heads. Same thing. Eliminated the pedal board, same thing. Changed guitar cords, same thing. Changed batteries in the bass, it quit. Is the bass's preamp going out or something? I was under the impression that if the battery in the bass got low, it would just quit, not squeal like crazy.