Turnable database with TimeLine

Agree with Tonywinsc. I think the KAB measurement makes more sense for average speed and constancy of speed.

I disagree. The Timeline measures the speed accuracy AND constancy with each rotation of the platter. How much more do you want or need? I understand Tonywinsc's point as a matter of theoretical discussion and extreme obsession, but if constant speed with each rotation of the platter is not enough for a person, I suggest that he needs to find another hobby altogether or perhaps listen to digital only.

Lew,
If you watch my video of the Raven AC-2 with the Timeline.....you can see exactly what you suggest albeit in reverse.
You can witness the Timeline laser moving incrementally to the left as the record is playing.....whilst when the tonearm is lifted.....the laser is stationary.
This means that the turntable is spinning exactly at 33.33rpm without stylus drag....but runs slightly slower WITH stylus drag.

Actusreus,

If a turntable slows down for a very brief moment due to the stylus drag and the Timeline registers it by shifting the laser spot but then remains constant, how relevant is that drag save for the very brief moment of the stylus settling in the grooves and the turntable adjusting its speed?

I have never witnessed what you describe.
Stylus drag is constant (but variable if you know what I mean)....so that when it slows down the speed of a turntable platter......that speed is changed for the duration.
It doesn't 'spring back' to accurate speed after the initial 'shock'....although with some direct drive turntables using speed-error correction.....this might be a possibility.
I just haven't seen evidence of it using the Timeline?

Tonywinsc,

The problem is you can't know if the drift is due to speed being something other than 33 1/3 exactly or if speed is actually changing during play.

This sounds like such a logical proposition....that no-one seems to argue against it and many have repeated it......
I suggest that it is impossible (without complex computer management).....to design an AC or DC synchronous motor to turn at multiple varying speeds which can line up a laser at an exact point every revolution at both 33.33rpm and 45rpm.
And as none of the motors in any of the turntables we know of.....have such sophisticated (and devious) computer algorithms inbuilt....this argument is simply childish?