Turntable speed accuracy

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.

Got a Brinkmann Bardo in to test drive and upon first listen the pitch of the piano was off, attacks were not sharp, so checking the speed with the Timeline showed it running a tad slow. It's easy to adjust and within 3 minutes had it spot on. This is how a turntable should be, doesn't seem that hard to get it right.
(Dealer disclaimer but not a dealer for Brinkmann..........yet!)

The KAB strobe disc is an approximation - a good one, though - and that can be easily proven... I place it on top of a test record, lower the cartridge (to include stylus drag) then set the speed with it.

Then, using a very accurate voltage and frequency meter like a Fluke, I put on a 1kHz tone on the CD player and measure the frequency - dead on 1kHz; this measures the instrument's accuracy. Switch back to the test LP with a 1kHz tone at 33.33rpm and the meter shows (naturally) some variations of about 1/1000, but clearly the center frequency isn't 1000 Hz. I usually have to lower the speed (in this case a VPI SDS).

Then I switch the speed to 45rpm and the meter should now read 1350Hz - yeap it does. The KAB shows I am going slow, but I know my speed is accurate.

I think the Timeline would be just as accurate, but why spend $900 when I can just measure a test frequency.