Turntable speed accuracy

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.

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.

Frequency variation does occur but happens over a period of hours rather than seconds, at least, that's what they teach you in school. You may well be right- every time I have checked the speed with a strobe, its spot on, but that probably does not mean a lot as the strobe relies on the line frequency. So all it does say is that the 'table is spot-on relative to the frequency on the AC line. The Speed-Nic thingy says its OK, but IME it does not have a lot of resolution...

FWIW, the KAB device uses (1) a much larger than usual diameter of strobe disc, which should enhance its accuracy, and (2) a battery-powered strobe which cannot be affected by variations in AC line frequency.