Weekly Q&A: Answers | Week of June 24, 2024

How does the lathe and "cogging" affect turntable playback?

Question:

Back with yet *another* turntable question! (Please stop rolling your eyes. ;-))

I'm trying to understand how so much incredible engineering goes into playback of LPs -- trying to ensure that there's no cogging in direct drive motors, etc -- doesn't seem to extend to the lathe itself. They don't have million pound platter setups (which isn't to say they're light), nor do they have special motors that avoid cogging through methods beyond the relatively well-known.

As such, aren't the efforts that go into some extreme (and extremely expensive) solutions limited quite severely by the underlying rotational performance of the lathe itself? In other words, if everything matters, you have to start with what puts the grooves down in the first place, and if that motor, platter, etc is less "advanced", then, yes, you're reproducing the source as it is, but if something like cogging is so audible, why wouldn't it be audible in every case, given "perfect playback"?

If not, why wouldn't tho…