The turntable speed should be at least as accurate as the tape recorders used to record, master, and playback the tape.
Constant speed is "much more" important than absolute speed.
Just buy a strobe disc and illuminate it with a light bulb.
The 60 Hz AC frequency does not fluctuate enough to worry over.
Adjust the speed of your turntable, or AC input (if you have a variable frequency supply like VPI SDS) for the lines or dots to appear stationary or slightly vary around a fixed position.
This is simple and more than sufficient. Tape decks are not all that accurate, and do go out of spec.
On my VPI TNT the SDS AC line frequency is set within .01 Hz.
If your platter is heavy, playing a record will not affect the speed.
Constant speed is "much more" important than absolute speed.
Just buy a strobe disc and illuminate it with a light bulb.
The 60 Hz AC frequency does not fluctuate enough to worry over.
Adjust the speed of your turntable, or AC input (if you have a variable frequency supply like VPI SDS) for the lines or dots to appear stationary or slightly vary around a fixed position.
This is simple and more than sufficient. Tape decks are not all that accurate, and do go out of spec.
On my VPI TNT the SDS AC line frequency is set within .01 Hz.
If your platter is heavy, playing a record will not affect the speed.