Tima, thanks for this. So the wow of .01 and flutter of .02 specifications of both the SME30/12 and TechDas AF1 are at inaudible levels. That is good to know. You can do a search of each turntable and reviews at HiFi + magazine for the test results. I don't think they go into methodology in the reviews, but perhaps more digging on the magazine website could lead you to it.
I presume David's intention with this thread was to discuss sonic differences between these drive types in general terms and the methods particular designers use to correct for speed errors. I wish there was more information out there from manufacturers about their design choices. Even if we reach a point where we can agree that the Monaco has excellent speed accuracy and consistency, it is how that speed is maintained that in part contributes to the sound of the turntable. And then there are all of the other design choices like mass, isolation, suspension, materials etc that give the Monaco its unique sound. If it were just speed accuracy that mattered, I think more people would own it.
Thanks for the affirmation that the HiFi+ magazine test results are available; maybe its a paid feature. Could you possibly be thinking of HiFi News? That site refers to Miller Audio Research. I searched for "sme 30/12 test results" and was pointed there; it asked for login credentials though I found no way to register. You'd think if someone was offering standardized testing for turntables, that information would be readily available and commonly pointed at. Maybe I had bad luck finding it. I'm inclined to believe 'table manufacturers are honest with their testing but freely open to challenge.
It has been easy to discuss the Monaco because the manufacturer provides so much information about it. By making the claims that they do, they become easy forum fodder, easily chipped at, though I haven't seen anything here to suggest their statements are other than they say. Nor have I questioned information from other 'table makers who provide it.
Rather than starting from drive types, or technologies or falling back on brand loyalty, is it worthwhile to ask if there is any sort of priority or precedence of design properties that better tables tend toward sharing. What is important in turntable design and implementation? Or, what is important to performance associated to top quality sound? If there could be some agreement on what is important then a look at those aspects for different drive types or manufacturers might advance the discussion. If the thread hasn't gone anywhere, maybe a turn to methodology.
I think Halcro tried when he said above: "The constancy and accuracy of a turntable’s speed rotation may not be the most important facet of its performance quality, but one would think it should be a sine qua non." To me that says speed accuracy and control of platter speed are necessary conditions for top performance, but necessarily alone not sufficient.
So are there necessary and sufficient conditions for top 'table performance? Could that sort of approach get to some agreement?
For example, another necessary but not sufficient aspect of 'table design might be: Minimal noise generation and noise rejection.
If some set of such conditions could be agreed upon, perhaps debate could occur over which of these is more important and which implementation method is better. For example, someone might offer: "The single most critical element of any turntable’s performance is the platter speed control. The more accurate the platter speed control the more accurate the frequency reproduction of the turntable."
Now to some extent numbers may help drive the notions of what is necessarily important simply in virtue of the better 'tables commonly exemplifying them, for example, wow and flutter figures below a certain audible threshold. On the other hand while small differences between small numbers seem like they may not make a difference, absent other ways of accounting for sonic differences between 'tables maybe they do. I will not use numbers to tell me what sounds right but after the fact they may tell me why. Heh. Hopefully I get to retain my subjectivist reviewer card.