Direct drive vs belt vs rim vs idler arm

Palasr, I am fairly certain the Timeline flashes more than once per revolution. (I cannot recall the exact frequency; maybe Mosin knows.) Thus it may detect short term speed instability, in fact, altho with what accuracy I cannot know unless I know the frequency.

You would think that the KAB strobe could also hint at short term speed instability, as the "33" would waver or even flicker back and forth while under observation. But I don't know how sensitive it would be to such aberrations.

Mosin/Richardkrebs – thank you for your excellent thoughts on this thread.

Mosin – as just an amateur hobbyist myself, most of what you have said is in sync with what I have heard with my TT’s the last few years. I agree that string drive could be a little fiddly, when trying to convert a belt design TT to thread/string. But I have found that on a string designed TT – once the string technique is learned (there was a learning curve with mine), it was pretty much plug and play after that for me.

RichardKrebs

It was actually possible to recognize the music being played at the time on the scope. The speed sensor was measuring these tiny errors and correcting. This could be observed by watching the motor draw current in sync with the music. An amazing observation.

I find this simply incredible.
Are you able to tell us what turntables / tonearms /cartridges you used during this analysis/testing?

I am now using laser tach to determine my platter speed and stability. IMO, it is the most accurate way to gauge the speed on the platter. Accurate to 1/1000 th of a rpm. Only $200.00. It should be placed on a tripod for the most accurate measurement. Monarch PLT 200.

http://www.omnicontrols.com/detail.aspx?ID=3720

An accuracy of 1/1000 rpm is 0.003%. This is only as good as most high end tt's. It needs to be an order of magnitude better than that. It will be good for dialing in speed, but not for examining Wow&Flutter. If it is off 0.003%, then the platter will gain/loose 1/3 of rotation per 10,000; assuming all else is constant. I'd call that good. Why doesn't anyone talk about the iPhone app? It at least plots speed over time for you.

The original Timeline flashes once every 1.8 seconds (1 revolution). The latest version, which is at least about a year old, flashes eight times every 1.8 seconds.

Tonywinsc,
I don't know how much faith I have in the accuracy of an iphone microphone!