My Impossible hum issue.

I have done everything that I have read about ground loops without success. My system is on an outlet that goes directly to the main panel with nothing else plugged into this circuit. None of the usual suspects are in this room like TV, radio, appliances or flourecent lighting. When using any other source other than the turntable, the system is dead silent. The turntable is on a wall mount turntable shelf. The speakers are on stands. This hum is only present when the turntable is the source. The hum is much louder with a MC cartridge than a MM cartridge. The hum is present when connected to an external phono preamp or the internal phono preamp of the my system preamp. I have tried every combitnation of grounding and not grounding. Whether or not I plug into the wall outlet or power conditioner/surge protector the hum persists. I beleive that I have tried everything except a different turntable. I have made sure power cables, speaker cables and interconnects don't cross each other. I've tried everything except moving to another state or hiring an exorcist.


The hum problem is an issue that occurs in most professional music areas. The solution is to install ISO Max transformers. It will cost you about $200 but will solve any of your hum problems.

etbaby, I don't think an isolation transformer would solve the OP's actual problem, since the short in the ground connection occurs AFTER where the ISO Max transformer would be inserted, between the AC source and the power cords. He had an interruption in audio ground.

I had a persistent 'hmmm' for a time that drove me sane....

And, as noted, a funky cable not grounding well.

Took persistence to track it down, and the obviousness of it... 🤦‍♂️😏

Glad you were able to find yours.... 👍👌

I upgraded from these a couple years ago but haven't really heard a difference--may be my hearing or may not but these are very low capacitance (essential for phono cables) and in your budget--i think Belden makes them for BJ:


If all else fails, get a Radial Engineering J-ISO or similar.  basically a 1:1 transformer for audio signal and it will at least prove whether it's possible to eliminate the hum.  I've used mine at various points in the signal path for troubleshooting