Direct drive vs belt vs rim vs idler arm

I don't think "cogging" had anything to do with the wavering pitch of my old SS Sapphire. Possibly the mounting of the motor on the plinth whilst the bearing and platter were suspended did have something to do with it. I think that cogging, if indeed it is audible at all in any well designed TT motor, would give a "regularly regular" type of distortion and would probably not affect pitch so obviously. I actually heretofore thought that what I heard with my Sota was due to the old stylus drag/belt stretch bugaboo, but that's just an unsubstantiated guess.

Interesting to note that the original AR turntable, which I used for years, also had the motor mounted on solid ground and the platter suspended. Yet it is touted as a "classic". I can't even remember whether it gave an accurate rendition of piano notes.

Lewm - the "cogging" mostly showed up as instability, most apparent in the bottom end. This was cleaned up with the updated power supply & on board regulation. This was consistant across many SOTA's we sold at the time. Sounds like you had a different issue.

Yeah. The bass on mine was muffled as well. (I totally forgot about that issue.) Could be I had the version you are talking about. But when you say "we", do you mean to say you were a SOTA dealer or otherwise involved with SOTA?

Yes I imported & distributed SOTA in this country about 25 years ago.

Most suspended tables have the motor fixed and platter/arm suspended to isolate the arm from motor vibration. that was the problem with wimpy suspension which would create oscillation and speed changes. This was especially true with suspensions that hold the plinth up, rather than when the plinth hangs, such as Oracle or Sota. Sota was able to fix the motor to the platter/arm plinth by changing the motor and regulation to virtually eliminate motor vibration and damping what was left. Works as far as I can tell.