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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.

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mrfrito's avatar
mrfrito
30 posts
 

I just purchases a Technics 1200G as a second table. I had a hum issue on the right side only. After trying all the same cures you used and a few more with zero effect. I bought AT headshell remounted cartridge ,now its dead silent !  If you can switch head shells that might be you answer. 

lewm
13,099 posts
 

Russ’s guess is as good as mine. You’ve eliminated most other options.

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adamsrpm OP
12 posts
 

I have tried movig the ground wires using one from the turntable to both preamps and just one or the other preamp or no ground at all. I have been using an upgraded interconnect cable (Pangea turntable cables with integrated ground wire) and not the one that came with the turntable. The turntable is a Technics SL-100C (essencially the same as the SL-1500 without the built-in preamp). I can hear a sound if I tap on the on the tonearm...maybe there is something wrong there. My control preamp is a Parasound Halo P 6 and the phono preamp is a Parasound JC3 JR. I realize I have budget gear, but I don't think that's the problem. I appreciate the input. Thank you.

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cleeds
5,957 posts
 

Is this a new problem, or did this setup previously work ok? What phono cartridge are you using? Can you hear the hum when the music is playing?

lewm
13,099 posts
 

Also, you haven’t ruled out an internal break in an IC wire, most likely the phono cable but could be elsewhere, that interrupts grounding. To check that just insert some cheap alternative ICs in place of what you’re now using. For one, try the Sony supplied phono

cable. Like Russ suggested also check cartridge pins, internal tonearm wires, and joint between headshell and arm wand. Is it tight?

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