Turnable database with TimeLine

Don, You (sadly) wrote:
"I am not a fan of servo controlled speed. The speed is wrong a lot of the time!
A properly designed turntable should run at a constant speed!
If there is stylus drag (that audibly effects sonics) , then increase the speed slightly." (DUH!!)

That is more of a rant than a rational statement. It reflects your complete misunderstanding of the problems associated with maintaining constant platter speed despite frictional forces (stylus drag) that are constantly changing in magnitude. I take it your experience with direct-drive turntables, if you've had any, has been a negative one. In reaction, you are creating a hypothesis based on no data and a paucity of knowledge. You may fairly say that you dislike this or that direct-drive turntable, but do not presume that your subjective opinions are necessarily applicable to all such turntables. Nor do you have any data that would lead you to understand why you did not like whatever you've heard.

About the SDS (and similar motor contollers) I agree with you. Any belt-drive tt motor that does not have a built-in motor controller circuit of some sort will benefit greatly from the addition of a motor controller designed to maximize the performance of the particular motor type. For example, a 3-phase AC motor is quite a different animal from the induction type motors used on early Garrards and Lenco. The SDS (and the Walker Audio Precision Motor Controller) work on a wide variety of motor types, but for the same reason neither is optimized for any one type.

Someone else brought this up, and it puzzles me too: Why the heck does the Timeline laser flash 8 (or 6) times per revolution, when we are only observing a single flashpoint at a time? What is the advantage? I had hoped incorrectly that the "extra" flash events were used to enhance the sensitivity of the instrument. (As I stated, if 6 flashes could be used to cut down the time interval between observations from about 1.8 sec to 0.3 sec, then the sensitivity begins to approach that of a continuous read-out, to make Tony more happy with it. But as others, including Tony, point out, this is not happening.)

Since the mass of the Timeline is concentrated over the bearing, giving the motor lots of mechanical advantage in moving it, and since the Timeline that I had use of is very reasonable in mass, less in fact than many record weights, it's hard to imagine that its mass would alter the results detectably. If the motor cannot handle THAT much drag, it probably cannot handle stylus drag either.

Maybe I am pointing out the obvious here. Our ears don't care about average speed. Our ears hear the minute variations in speed.

Tony,
Maybe it isn't as obvious to some, but I hope our posts about cogging and other aspects of a turntable's design will be helpful, though. It's a lot to expect guys who aren't that interested in the mechanics of it all to understand why what they hear in a given turntable isn't exactly right, or is decidedly different from a very similar one. Hopefully, enough of the participants here are articulate enough to explain some of the things involved in ways that the casual onlooker can understand, though.

In any case, it isn't that easy to sort out all the nuances of what should be a very simple device that has the seemingly simple task of quietly spinning around.

@Lewm

In this entire thread "NOBODY" that used the timeline and "observed" the speed changes due to stylus drag came out and said they detected "ANY audible sonic changes!'

This whole tread is about drag measurements that are "NOT AUDiBLE" on well designed "high end" turntables set up with a strobe!

"Climb it and Rotate"

Don.
re your post to Lew. "Nobody has used the timeline.... and detected any audible sonic changes."
Firstly. The time line shows average speed per revolution. A TT that passes the timeline test has a "consistent average" correct speed, no more than this. We cannot see what is happening at a micro time interval level, but we can infer.
I would be surprised if anyone could detect the adjustment of this average speed back to say 33 1/3 if the TT in question showed slowing due to stylus drag. We are talking small changes in absolute frequency with this adjustment. The owners of these TT's cannot however adjust the TT's dynamic speed stability since this is intrinsic in how the TT was built and designed. This includes its power supply and controller. Of course there will be no audible changes since these owners are making no changes to the TT build, design itself.

However there is, I believe, at least one person posting here who has direct experience with the audible effects of an improvement in resistance to stylus drag and dynamic speed stability.

That poster is........you.
You reported a "huge" improvement in the VPI when using the SDS controller.
This device makes the motor run more consistently. What you heard was a platter rotating more accurately at a micro speed level. It is quite possible that its average speed with a load, did not change, so no difference would be seen with a Timeline. But you correctly reported the positive changes.
It would make logical sense that a motor which runs more consistently would be better able to respond to and minimise speed changes due to a dynamic load, such as that caused by stylus drag. So it would further be logical that the VPI would show greater resistance to speed sag when lowering the stylus (no load, with load) and we would likely see an improvement if this test was done with the Timeline.
So we can say that you are a champion of a design that reduces speed changes due to stylus drag.