Hey guys, This just started happening yesterday to my Jazz Chorus 50. At practice, after playing a song, I noticed there was a very loud hum in the room. At first I thought it was the PA starting to feedback, but then I noticed it was my amp. It was almost like a low, steady feedback. I turned the amp off, then back on and the sound was gone.. it seems that I just need to play it a bit to replicate this, so powering down the amp seems to reset this issue. Also, it only happens when the spring reverb is turned on and gets louder the the reverb level is increased. Does anyone have any idea what could be happening?