Turntable speed accuracy

Ralph, By all accounts, a really accurate subdivision of the phases plus really accurate control of voltage and frequency can render a major noise and vibration reduction in 3-phase AC synchronous motors, but my disclaimer is I don't know nuthin'. I am mostly quoting the teachings of Mark Kelly.

Lrsky/Lewm - my money on an 80's demonstration by Magnepan would be an Oracle Delphi tt with the Magnepan unipivot tonearm, this was a popular combo of that era in the US if you weren't in the Linn/Sota camp.

Atmasphere - I think you are too optimistic on the quality of the US power supply. The US grid is split into 4 quadrants and the supply agreements in place with the power providers have delivery standards etc, but there are NO standards in the agreements on frequency stability. As you will know frequency will vary with load fluctuations on the grid. I have seen figures of 60hz with an accuracy of 5%. This issue is currently being investigated.

I have to say, this thread has been a good learning experience for me. Other than changing my phono cartridge now and then and doing basic maintainence on my tt, such as belt change and bearing lube, I have just listened to my records on occasion. Over the years I set my platter speed by the supplied strobodisc and flourescent light and called it good. But over this past month here is what I have learned. First, I learned that my speed was low by a couple of percent. I was able to dial in my speed exact by using the 3150Hz test tone on an old test record that I had and the iPhone app. That app is a very useful tool. Interestingly, with the speed dialed in dead on now, the strobodisc still shows a stable pattern. So the strobodisc/flourescent light method is not very accurate, ie. >2%. Second, not only has the rhythm and timing of the music changed, but the bass is tighter, the attack stronger. I noticed this playing a couple of old records that I have listened to many times over the years. The timing was so different from what I was used to that I had to go back and double check the speed setting again. Now I have to listen to all of my records all over again at the correct speed. Good thing I am still young. I conclude based on what I have learned that speed setting is as at least as important as speed control. In fact, I am wondering now if the differences heard with respect to rhythm and timing are really based on the speed setting of a tt more than Wow and Flutter- ie. if Wow and Flutter are less than 0.03% or so.

Dear Dev: Seems to me that a high cost not only in a TT bearing has to see not only with its design and tolerance level but with the quantity you ordered and obviously marketing.
If that same item is builded in 10,000 pzs. instead 50 you will see the big big difference in price.

During our " long " tonearm design time we learnedd many things about and if you can and with some items/parts sometimes is better to build it at home by your self.

Regards and enjoy the music,
R.