Jolida Hybrid humming noise through speakers?

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!

Jeff, I have a 1501a that was sent back to Jolida because the left channel failed. When I got the amp back it had a similar hum, even though none was there before. Much to my dismay, it had to go back. I was pretty frustrated as I was without my amp for a month.

Jolida was great. They sent me a new one and pick up shipping for the old because it left their repair center with the hum

Chip

I have had a number of Jolida amps. I have a JD301BRC now. The sound is great,  but the buzzing noise through the speakers is getting worse all the time. A couple of the other  amps I had also had a buzz coming  through the speakers. I would not think the tubes would cause it, but that is possible. A bad ground could, and also a bad transformer. Any number of things could cause it. I like the sound of Jolida hybrids, but it seems buzzing is a common issue. 

ANother thing to add- I just broke off the 3rd pin (ground pin) plugged the power cord into an extension cord and the extension cord into the wall socket- buzzing stopped. I do not believe a better power cord, or different power cord would help, but there may be an issue in the amp at the power cord connection having to do with the ground. 

Buzzing from both speaks, independent of volume. Found a spare 3-prong power cable, cut the ground pin off with a hack saw, covered the stump with some electrical tape. Plugged it in...

NO BUZZ!!!

Seems to have been a ground loop issue. Happily listening now!

Thanks, all.