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SME 20/2 Finger Lift Hum

On my SME 20/2 fitted with a Lyra Argo i, there is a hum whenever the finger lift is touched, but very quiet otherwise, and importantly, when the record is playing. Has anyone encountered something like this and figured out how to correct it. All possible ground combinations have been tried with no change. Again, the hum is only apparent when the finger lift is touched. Thank you for your help.
rsnoceanview

Showing 2 responses by larryi

larryi
3,716 posts
 
Unless the person touching the arm was also simultaneously touching another another component which has a different potential, I don't see how this is a ground loop. It seems like the person's body is acting like an antenna.

The easiest solution would be to cover the armlift if this really is a problem (perhaps shrink wrap with heat applied directly to the wrap and not to the cartridge itself).
larryi
3,716 posts
 
If I understand the situation, this was NOT an issue with a prior cartridge, but, it is an issue with the Lyra Argo. If that is the case, it may be the case that the Lyra's aluminum body is part of the conductive pathway. In that case, you may be able to do something with plastic screws, but, depending on how conductive is the headshell and the body of of the Lyra, you may also have to put some kind of barrier between the cartridge and the body. Keep in mind that the Lyra body is designed to make a very tight physical contact with the headshell in order to effectively drain vibrational energy from the cartridge into the arm for dissipation by the arm. That "insulation" might compromise that objective.

In short, I would go with Lewm and consider insulation of the armlift as a permanent solution.
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