hi jeff, i also have a jolida 1501 that made a humming noise at the speakers. i spoke to mike at jolida and he suggested that the hum might be coming from ground loop noise. he suggested floating the ground by removing the center ground pin on the outlet end of the power cord. quess what, it fixed the problem with no more noise. good luck!
Jolida Hybrid humming noise through speakers?
I have 1501RC and when the amp is on, there is quite a noticable humming sound that comes through the speakers. You don't hear it from the amp itself, but throught the speakers. You can hear it from several feet away. I have this plugged into a power strip/surge protector, but my other power amp had no problem. Is this a common thing with tube amps? Is there something that can be done before I send it out for repair? Thanks