My Carvin B1500 started making a noise in the middle of a song, last night. It did it 4 or 5 times during practice. The only thing that would make it quit was cycling power on the amp. Same outlet, same practice space, same bass, brand new (but used several times) Monster bass instr cable, nothing's changed recently except for this new problem. It sounded like I'd unplugged my cable from my bass and was handling the chord's end. Anyone have any idea what this is???