SDS question

OK...I forgot belt slipage. I am a DD guy where the speed of the platter is the same as the motor, and the motor is exact. I really don't think that there should be any belt slipage...you probably need a new belt.

Its been a while since I was up to date on TT technology. What kind of motor is used? A synchronous motor, common decades ago, would assure that the rpm was exact ("dead nuts" is the technical term). Bearing lubrication, temperature or phase of the moon would have no effect. Only a change in line frequency would affect speed.

What kind of motor is this, and how is the speed regulated?
Variation of line voltage (but not the frequency) is common, and I would be surprised if a TT was sensitive to voltage variation (within reason).

For example, my DD turntable has a strip of magnetic recording media on the underside of the platter which is recorded with a HF signal. A head (like a tape recorder) reads this signal which is compared with a quartz crystal generated signal and the difference (if any) regulates the speed. It works great.

Jameswei...Thanks for the info. Of course my synchronous motor can slip too...it has to when it starts up. However, when it "locks in" to synchronous operation this is indicated by a LED.