I’ve read a number of questions and responses here and elsewhere in regards to Turntable hum but still have a question in regards to my Stanton T50 belt drive.
Long Story Short, When I touch the turntable or tone arm, the low pitched hum reduces to almost nothing.
The hum happens no matter where or what gear the TT is plugged into and ground wire is attached to.
My intended and current signal path from TT is through an ART DJPre2 into an ART CleanBoxPro (to change to a balanced +4dB stereo level) then into my home studio trs patchbay system.
Nonetheless, when I touch the turntable or tone arm, the low pitched hum reduces to almost nothing.
Any suggestions would be appreciated. BG
Welcome to the forums @bgsw. It sounds like your tonearm is grounded to the phono preamp (preferred). The reason the hum reduces significantly when you touch the tonearm is you’re providing another electrical path to earth ground through your body. One aspect of grounding that can cause hum like this is having multiple devices in the signal chain connected to different ground potentials (locations back to your power panel). See if there’s a way to connect all of the TT/phono preamp etc. components to the same outlet which would have the same earth ground wire connection back to your panel. Another name for what may be your issue is “ground loops” which refers to noise currents flowing in the grounds which normally are there for safety purposes only in case a hot connection touches equipment chassis. Equipment ground ideally carries no current under normal circumstances.
EDIT: Another possibility is that your tonearm itself is not connected to the TT ground wire and is electrically floating. That would also cause the symptoms you describe. If you have an ohm meter you could check that the tonearm is connected to ground first.
EDIT2: Also if you have any light dimmers these can raise hell with TT signal hum. Very sensitive signal that’s so small lots of things can upset.
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This issue has driven me nuts in the past. As kcleveland points out, it’s inevitably due to a ground loop caused by a component (or components) in the system floating at a different chassis potential. When you think about it, it takes a really small potential difference to drive current through a ground path sufficient to cause hum.
Understand by what I’m about to suggest I do NOT recommend it as the permanent solution. However, I’ve found one way to at least isolate which component is the miscreant is to use a single three to two prong cheater plug and experiment with one component at a time to find out which component is the cause (hopefully). Then, explore how to to properly ground your components without defeating the 3rd prong. It all comes down, in my experience, to identifying which component in the chain has that ground potential differential relative to the others.
Good luck.
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Thanks to you both for your guidance.
I have all related gear plugged into a “Monster” Power Conditioner and have run the TT ground wire to the “Monster” ground lug as well as the ground lug on the ART Preamp and even both.
I’ve also taken the TT apart via the bottom and noticed that the tone arm green ground wire is connected to the main TT Grounding “system” but I will definitely do the suggested tone arm check.
I also replaced the 4 headshell cartridge wires with, I believe, Ortofons.
My Focal Monitors are connected to a PreSonus Monitor Contoller that has rca inputs to which I’ve connected the TT directly, bypassing everything else and the hum remained.
When I did this, I plugged the TT into the same (Furman) Power Conditioner as the PreSonus unit.
Thanks again for your suggestions that I will definitely do. BG
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