Ground loop related to VPI SDS/motor at 45 rpm?

I have a VPI and SDS. Can you tell me a little bit more about exactly what you are hearing?

It's a hum or low buzz coming through the speakers...sounds like a ground loop to me. It only happens when I put the stylus on the record (and only when it's moving at 45 rpm). I suppose I could connect the pre-amp outputs to my oscilloscope to prove that it's 60 Hz, but that's what it sounds like to me.

I have to admit, thats an odd problem. Honestly, I'm guessing on this, but you may try 3 things. I assume you have a vpi turntable. On my scout, the motor is completely separate. 1. I would check for a resonance either from the motor touching the table and/or, if not touching, just make sure the motor is sitting securely and everything looks ok. 2. Run an extension cord from another outlet in the house that you know is not on the same circuit as you equipment and start plugging things into it. 3. Watch the record spin at 45, unhook the motor and belt and spin it by hand as best you can. You have probably tried some of this already. I can't think of anything else other than swapping different components out or calling vpi. I wish I could be more helpful.

If it only happens with 45rpm and not 33rpm setting, it sound like something is wrong with the SDS