Turntable speed accuracy

A robust drive is really important in a good turntable!

Very interesting comment. Jibes with the idea that the quality of the power supply is v. impt in amp and pre-amps as well. Not sure why, maybe its just a co-incidence? But after having my pre-amp's power supply upgraded, I am more convinced than ever that it is true for the electronics!

Halcro- Yes, I had read that and was trying to re-state it in a way that might make sense to those of us who are not musicians. Not sure how common this is amongst "us", but I cannot carry a tune in the proverbial bushel basket, let alone have any idea what a 12 hz variance in pitch means. I am in total awe of musicians, esp. singers!

A fast start up direct drive turntable does not necessarily have higher torque. Some DD tables boost the torque only at the first couple seconds to get the platter up to speed and then lower the torque to just enough to keep the platter running. The image that DD has higher torque is due to the popularity of Technics turntables, especially the SL-1200mk2 and SP-10mk2. But Technics is, of course, not the only name in the DD game.

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Thank you In_shore,
But what happens if the orchestra being recorded is already tuned 12Hz lower than 440Hz which means that at 33.33rpm......we are getting 428Hz for the note A?
If our turntables are then running slow by....say 12Hz.....it can't really be good?
The aim should really be....to be as close as possible to an accurate and consistent 33.33rpm?
Cheers
Henry

Hiho, There is much ignorance among us as to how the servo system of this or that direct-drive turntable actually works. From my casual observation, they are not all the same, by any means. But from a Newtonian point of view, max torque is only ever attained at the moment of start-up, when the platter is completely at rest and then must undergo a change of inertia to being in motion at 33.333... rpm. So, the huge torque of an SP10 Mk3 is what gets its 22-lb platter up to speed in 0.25 seconds (or something like that, according to the Mk3 owner's manual). Once the platter (any platter) is in motion at its set speed, it does not take much torque to keep it there, except that which is needed to counter-act stylus drag. Here is where the design and implementation of the servo mechanism is different for different vintage types. For example, I am not sure I understand exactly how the L07D system works, but it appears that the full torque of the motor is only invoked when or if there is a major loss of speed for whatever reason. (I think the service manual says more than a +/-3% speed deficit.) Otherwise, the drive system doles out torque in small increments, and I think this is done to minimize the audibility of tiny corrections that need to be made to maintain exact speed. The engineers of the 1970s and 80s were well aware of all of these issues that we are now still obsessing over. The L07D may turn out to be my all-time fave, and it's not the highest torque in town.

And, lest we forget, among designers of both belt- and direct-drive turntables there seems to be a divide around weak motor/huge platter vs strong motor/light(er) platter. There are logical arguments either way. So, I would not be so bold as to make any declarative statements.