Debuzzing a Wheaton TriPlanar problem

Thanks for your considered response. My former career was as systems software developer, and I appreciate your debugging skills. Occasionally (of course) there is feedback while the stylus is tracking the groove. My gut reaction suspects some sort of intermittent feedback. as you suggested, from the cartridge itself. It is an AudioQuest 7000 now some 15 years old and my new Masseto preamp deserves something better anyway. I'd hate to think it's the shielding on the Cardas cable touching the tube, because that would require a re-wiring but that's what my hands-on experience feels like. Cartridge replacement first, then rewiring. The multiple groundings were done to successfully eliminate a constant hum at table installation time.

Dr_John, I think I did not read your first post all that clearly. Now the problem sounds to me like it might be a sort of RF oscillation in the preamp. I would not characterize this as 'feedback'... it sounds like either a very bad ground or RF in the system. The fact that you can touch the arm tube and have the sound go away for extended times suggests that its an RF problem. I don't think its anything with the Cardas cable, as when you touch the arm tube, you should at that time be able to keep the arm still.

ok - another piece of evidence to add, and this may be the most telling. When I grasp the finger rest at the end of the tube, the hum gets really loud. Just squeezing the tube itself ever so lightly stops the noise. And this part baffles me - all I can think of is a defect in the cartridge.

RFI/EMI problems at tonearm wires can tend to jump around unpredictably as you describe and vary in proximity with the human body. Grounding the tonearm or TT is sometimes not enough, and screened tonearm wire may be necessary to resolve the problem.

Does the hum continue when the cartridge pins are disconnected from the tonearm wires?

You might experiment by relocating the TT to another part of the room. The current location may be in a bad RFI field or too close to in-wall AC wiring or to the AC PS of another component.

Now this is making more sense to me, and I thank you. The TT is 6 inches from the wall which conceals all the electrical lines from the apartment's circuit breaker. And I must ask what is 'screened tonearm wire' ? I want to try this fix before relocating the equipment rack. Thanks.