Turntable speed accuracy

Lewm: "no need for me to know anything more than what I have learned by casual reading."

That's very zen. I need to do that myself. Bill Belichick has a sign at his team facility that says "Ignore the noise." Good advice.

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Hi Dev, the bi-planar air bearing for my turntable in the 1990s was only about half the cost of this new one. But this new one has much tighter tolerances and will do the same job with 1/3 the air volume of the former.
In all engineering the cost/performance ratio becomes a steep curve towards the most tight tolerances, as the manufacturing effort and production reject rate rises in a much higher rate than just proportional.
As said before - there are a lot of good quality bearings out there for a fraction of the costs, suitable to provide very good bearing for a high end turntable.
The turntable using this bearing ( plus the USD3500 dental/medical grade compressor needed to run it ) won't ( can't ...) be a commercial product anyway.
Cheers,
D.

However, he did also comment that with a true 3-phase AC synchronous motor controller (so you can throw away the phase-splitting capacitor), the Papst would have been MUCH quieter and therefore might outperform the Thorens motor in all other respects. So, Ralph, have you ever used such a motor controller with your Atmasphere [sic] 208 turntable?

Hi Lew, If the motor was noisy then its likely that there was some sort of defect. All I have ever heard from them is a hiss related to the air moving around the rotor. In my application it is isometrically mounted, so noise simply isn't an issue. What I have heard about the controllers is they are used to get greater stability than the AC line offers, but I am dubious about that- the AC line is quite stable!

Dertonarm
Fascinating and of course your table would be something to experience even though I could never afford it along with associated components.
Have you now or are you planning a web site for your products?

Lewm,
Been thinking about your 'what turntable' question...
It may have been an Oracle...it's been a long time...sorry.
The tables of note then were, as I said, Linn, SOTA, Oracle...no doubt a few others, but they were, in my little part of the country the bigger names.

Larry