General comments on SOTA

Yes, the Papst motor fitted to the early SOTA tt's was a dc servo motor. Papst also made others such as the external rotor ac (3 phase?) motor fitted to the Empire tt's(amongst others) as well as direct drive motors for Revox (B790). I think Papst also had something to do with the Dual EDS dd motors.

I have always been interested in SOTA vacuum hold down technology. When I was first exposed to their product back in the 80's, I think that was their claim to fame, so to speak.

Now I notice they have a line of non-vacuum versions that use traditional record clamps.

Can anyone comment on the effectiveness of the vacuum hold down system vs a clamping system? Is the mechanical clamp down system as good as vacuum and is this a case of diminishing returns?

As far as flattening warped records nothing works like vacuum.
I had a Star for many years and ended up using the platter/bearing and vacuum system from it in a diy turntable... the vacuum hold always worked flawlessly (except for really dished records where you need to find a way to push the edge of the record down till the vacuum grabs).
Recently I"ve made a diy direct drive tt which uses a normal clamp arrangement and while very good I really miss the vacuum of my other tt.

I have used a Sota Cosmos IV vacuum table and a Transrotor Fat Bob with center clamp and edge ring weight. The Sota vacuum is much more convenient and works just about every time except on very dished records. Also, the pressure is uniform across the record. With the center weight and edge ring, you can really flatten badly warped records, but I dont think you get as uniform a coupling between platter and record.

As to sound, I can't really say one is better than the other as there are too many other variables. Both sound excellent, but the Sota is truly plug and play, and you absolutely cannot hear the vacuum while playing.

By the way, the Sota center clamp is excellent.

I too am riggin up a diy table with the Sota vacuum platter