Direct Drive Rumble

DD TTs do have less rumble (theoretically) because they are free of the assymetrical side force on the main bearing found in (most) belt drive TTs.

Therefore, assuming high quality bearing design and proper lubrication DDs are essentially free from rumble but can suffer from a kind of 'flutter' produced by the motor pulses. The better ones use a feedback system (e.g. Micro Seiki) or a clock (quartz) regulator like the Technics, JVC, and Goldmund Studietto to name a few.

You can find a lot of great info on DDs at:

http://de.geocities.com/bc1a69/index_eng.html

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Isn't rumble referring to the bearing effects (the quality of the bearing design and manufacture)? Wow and flutter are the primary parameters affected by belt vs DD.

Thank you, gentleman. The bearing issue had never before come to my attention. It would seem, from what you are saying, that direct drive has the greatest upside potential since it will experience less rumble effect and no worse than equal wow and flutter.
I started another thread a while ago about the suspected superiority of DD and the arguments surged back and forth for weeks resulting in nothing conclusive.
Near the end of that period, I had occassion to visit Chris Brady of Teres turntables at his home and witness the unveiling of his new DD table. It was clearly superior to his best BD which was used for comparison. There was more of a sense of drive and attack in the DD. The BD by comparison sounded "lazy". Chris is now convinced that DD has a greater potential for playback. And so am I.

I hope there will be a new generation of DDs in the future. It would be interesting to see them made with an inverted platter bearing. Is the Teres made that way?