High mass vs Low Mass Turntables - Sound difference?

Lew and harold,

I remember that ET arms were popular on Oracle tables but I never understood why?  I owned an Oracle for awhile and found it to be EXTREMELY sensitive to balance.  Mine had a sort of counterweight balance under the platter but I still had problems, even with a conventional pivoted arm (SAEC).  Maybe later versions of the table remedied that?

Czarivey, You own one of the few LT tonearms that operate as you describe.  I believe Mr Rabinow invented the idea of having a little motor move the tonearm in increments, when it makes contact with a tiny switch located back behind the pivot.  Like you say, this assures that the Rabco tonearms (and the Goldmund TF tonearms which copy Rabcos) are swinging in tiny arcs across the surface of the LP, for good or ill.  But most modern LT tonearms are either riding on an air bearing (with a rigid 90-degree connection between the arm wand and the air-borne carriage) or gliding downhill toward the center of the LP because of dishing of the LP surface, a la the Souther.

There are few modern linear arms made with air bearing just like air-hockey.

On the contrary there are many -
Eminent Technology, Air Tangent, Cartridge Man, Bergmann, Kuzma, Walker, Zorin, Terminator just to name a few.

I never had any kind of problems using Terminator T3Pro LT on my ORACLE DELPHI.The sound was very convincing, quite incredible to be honest for a BD suspended deck. The best I ever had heard hands down.

It is not possible to balance an air bearing arm on the Oracle if it is properly set up, suspension is too soft. Been there. If you balance the arm to 0, i.e. floating, you can see the arm drifting either side of the centre of travel as the suspension shifts. This is clearly audible in a good system.

As 3blm  said, high mass platters have lower wow and flutter and a lower noise floor. If the manufacturer is careful, and uses a low power motor, wow and flutter pretty much disappear. If the bearing is air, the noise floor converges to zero.