Turnable database with TimeLine

There are two subjects here: 1) How well do the differing turntables hold speed to exactly 33 1/3 rpm? 2) What is the effect on platter speed during heavy groove modulation?
Subject 1 is being answered with the Timeline device testing. And the Timeline device is being used appropriately for these measurements. This is a perfectly valid and interesting exercise.
Subject 2 is also a valid and interesting point. The Timeline device, however is not the appropriate tool in this case. A fine tachometer is required. I find this subject interesting and especially if it were possible to compare the results of speed control with a heavily modulated record on all three basic drive types- belt, direct and idler.

Halcro,

I just watched your video of the Raven, and I must say I am puzzled by the speed changes. What's causing it? Assuming the VTF is stable, as it should be, why would the turntable speed up as the tonearm tracks toward the spindle?

Lewm, I also thought that there is a new version of the TimeLine with more lasers around the perimeter of the device. However, I just spoke to a dealer today who confirmed with Roy Sutherland himself, that there is only one TimeLine version and that the device has not be changed since its introduction. There is only one laser on the device. It flashes at some interval to create six equally spaced dashes around the room. This description is consistent with the unit that I borrowed to make my videos. Apparently, I had the original and only version.

I have tried a digital tachometer and found that I could not get repeatable readings even while I held the device against the edge of a table and pointed the beam toward the reflective tape. It varied by an amount much greater than my KAB and the Timeline indicated, so it must be defective or I was not using it correctly. I will try it again.

Actusreus.
Assuming
1)the stylus drag is constant throughout the LP
2) the TT slows due to stylus drag,
3) speed control is open loop ( maybe)
Then it will naturally increase in speed as it tracks towards the centre grooves.
This is a torque moment effect. On the outer grooves, the drag is acting on a larger radius so it requires more torque from the motor to counteract this.

I tried using my Fieldpiece digital tachometer again last night. I tried three l locations and placed the device on a stationary platform. In each test, the device read 33.XXX but the XXX had slightly different values at each location. These speed readings did not change when I introduced stylus drag. In fact, once the 33.439 or 33.352 was fixed I could not seem to get it to change value without turning the unit off and resetting it to zero. Nor could I get it to ever repeat a reading. Both the TimeLine and the KAB show the effects of stylus drag on my turntable. Perhaps the tachometer is just not sensitive enough to tiny changes.