Turntable speed accuracy

"A turntable needs the right speed, knowledge to make the area of the needle silent and a solution to remove the energy from the tracking." Amen. Very Zen.

No doubt repeating a point someone else has made.
If the speed is off, the pitch is off, a cardinal sin for me.

Interesting story which I shared years ago.
I was in Chicago at the CES...circa 1984. I had lobbied Magnepan for their line a lot. A LOT, LOT, LOT. To their credit THIEL beseeched me to carry Maggies.
At the CES in Chicago that year, I went in to the Magnepan booth...they were, as I recall playing the MG III's.
Jim Winey asked me to 'have a seat, listen and tell me what you think.'
I had told him on entering that I'd been trying to get his line to no avail...like a Zen Master, he listened and nodded patiently...'Sit, Listen'.

After I listened to a cut I knew, from 'Jazz at the Pawnshop', I stood.
Mr. Winey said, 'What do you think?'
I said, 'It sounds great, just one small issue.'
'Yes?'
'Your turntable is turning too fast, the pitch is sharp.'
He only nodded.
A week later, I got a phone call from their then Director of Sales Dave Carambula (memory)...
'If you still want the line, we'll ship tomorrow.'
They did.
When Dave showed up, I introduced my Wife...he said, I don't remember her, but we remembered you...especially Mr. Winey remembered.'
'Oh?'
'Yes...he told me, give that man our line, anybody who notices the pitch differential deserves to have us in his store.'
He turned to my wife, 'Yes, your husband's the one who told us that our turntable was set up wrong.'
That is how I ended up with the Magnepan line.

Funny how the best stories are always the true stories.

Larry

What turntable?

The argument between measured performance and audible performance must be as old as our hobby. Both sides of that coin are being described here regarding speed.

I don't have any musical training and I expect my perception of timing (tempo) is better than my sense of pitch, which is certainly not absolute. A few years ago when I bought my SP-10 Mk 2A I had a tech friend go through all the calibrations described in the Service Manual. The strobe showed steady speed but when I listened to any recording with a sustained piano cord I could clearly hear a wavering. My friend could not find a correction for that so I took it to a professional tech. With the aid of one of my observed recordings he was able to find another adjustment that eliminated the wavering. After that there was not observable difference in the strobe but there certainly was an audible difference.

Thus I don't feel any need to investigate this Timeline device.

This is an interesting discussion! Thanks all who have participated. I'm particularly interested in the role of the type of motor as it relates to speed stability. It seems that DC motors require a lot of fancy/expensive control mechanisms to achieve speed stability, many with a feedback loop of some sort for control. And as with any feedback loop, there is an opportunity for oscillation, which is certainly a problem.

On the AC motor front, you have synchronous motors, but perhaps the best performance came from the 3-phase motors, like the old Papst pancake motors that a number of high-end turntable makers used to use. I think technically they are eddy-current motors, and hugely inefficient. But their design with the spinning outer rotor and inner coils gave the motor a bit of flywheel effect regardless of the type of platter being used. It seems to me that the Papst motor is what is in the turntable that Atmasphere was raving about earlier.

Are there other 3-phase eddy-current turntable motors still in use today? I know that Papst ceased production of theirs, and it was problematic in several areas (the vanes make a whirring sound, for instance, and the bearing technology is 1950's era).

What other types of motors are best for speed stability?