Back on track...
The discussion so far has been about torque, but in my opinion the most critical component of a turntable may be the platter. With all three types, belt driven, idler driven and direct drive, the platter can be the make-or-break piece because it is the final interface to the record, it is key to how inertia works and it is the interface to the rest of the mechanism. That said, I really believe that a turntable should be seen as an entity because, like the audio chain in your system, it is only as good as its weakest link. There is no single part, no matter how seemingly insignificant, that should be overlooked. Designing a decent one is easier said than done for certain.
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