Calling all analog experts

A general comment from an engineer with long experience in the design and testing of precision servo loops..

If you want to maintain precise uniformity of mechanical motion (such as RPM of a turntable) in spite of variable drag and/or motor torque, there are at least two ways to approach it.

The old fashoned way would be to use a massive (heavy) turntable/flywheel. Variations of torque, either due to drag variability or motor torque fluctuation will be very slow to change the RPM, and since these torque fluctuations a very brief, the RPM change is very small.

The modern way would be to use a very lightweight turntable/flywheel driven by a powerful computer-controlled motor. The motor, under control of the computer, applies the torque that, with the old approach would have been generated by flywheel inertia. In fact, the computer could simulate a flywheel much heavier than any real turntable. This approach needs a lightweight table so that its inertia doesn't "get in the way" of what the computer and motor are trying to do.

I really don't know if anyone has found it worthwhile to design a turntable using the latest technology (the market is very small) but I would warn anyone with a direct drive turntable that adding turntable mass may degrade rather than improve speed stability.

Same goes for adding extra capacitors to a regulated power supply.

Jasonic...These threads do tend to evolve into discussions related to, but not directly answering the original question. Frankly, we often answer one of the prior posters, rather than the original thread author. In this case Dougdeacon's mention of me by name, referring to a prior discussion, caught my eye. Sorry to confuse the issue.

Regarding the particular units that you have under consideration I claim no expertese. To put it bluntly, I am very well served by my high tech but definitely non-approved by audiophiles Sony ps X800, and have, for some years invested money elsewhere in the system. I follow TT technology just for the interesting ideas involved: not with the idea of buying a new TT.

I agree that the best pickup I ever had was MC, but for practical reasons I now use a Shure V15MR, and it ain't bad at all. Two points with reference to prior comments.

1. I don't think that trackability explains MC superiority. No cartridge beats the V15MR on this score, and it is a MM design. I think that Shure invented the term "trackability" and put out the test record that is commonly used.

2. Although a MC pickup usually puts out a lower voltage signal its impedance is also low, so noise pickup is not the problem that one might suppose.

Finally, I don't see where anyone has yet mentioned the issue of the user-replaceable stylus. This is a big plus for MM units.

IMHO, a MC is like one of those women that you really want to date a few times, but is hard (and expensive) to be married to.