Hi,
I have a ~50yo vintage amp/receiver that gives me sound I am happy with. All is good, except for a humming that I hear between the tracks if I put the amp to higher volumes. It's obviously getting worse with headphones, but even at 1.5 m distance to my speakers I can still hear it.
According to my phone app the humming is at 50Hz harmonics, to be precise at100Hz, 150Hz, 350Hz, 450Hz, etc. See the brighter vertical lines in the attached spectrum diagram below.
I believe I can hear a similar humming if I put my ear close to where the transformer is, didn't open the case though yet.
I upgraded most all the large caps about 4 years ago, the amp comes with a 2 pin EU plug. BTW, the radio receiver part is broken, I somehow managed to damage it during the recap process.
Anyway, I attached the amp's ground connector to the heat radiator, it helped a bit. Tried switching off other electrical aplliances that might be connected to the same power rail in the house, no difference.
Time to replace or is there anything I can try to reduce this noise/humming?
Screenshot_2023-04-29-12-58-23-449-edit_org.intoorbit.spectrum.jpg