With the researgence of air bearing turntables by Techdas and now Kuzma, I wonder if an air bearing for a TT platter is really a plus. I am not talking about possibilities of air puffing from the pump translating to the bearing, though unless properly accounted for and filtered that can be an issue as well. I think there is a greater issue regarding the motor platter interface and the effect of friction on the motor output and torque curve. The needle may have a negligible effect on the platter speed but if the motor is already fighting friction and applying torque, like in the Garrard grease bearing or the Thorens TD-124 eddy brake, it is already putting out more grunt to plough through the viscosity of the grease or brake so the needle drag is nothing in comparison. I suppose the addition of mass to the platter makes a difference in the inertia of the platter to make up for the lower torque of the motor and lack of motor output based on a low friction system, but I recall reading somewhere that the three motor scheme of the AN turntable put out equivalent rotational torque to a platter weighing a quarter of a ton.
I believe J.C. Verdier wrote his own opinions that friction was a good thing as it required this extra output by the motor and all of his turntables, even his nouvelle platine, have an oil bearing even though it uses magnets to lower but not suspend the weight of the platter. Zero friction can cause the motor and platter to be effected by the stylus drag and in the case of low mass platters as used on the old DD tables, may cause a hunting for the correct speed in a reactive feedback loop from the speed servo, which caused some to walk away from DD drives, although I have found the best ones to have serious sonic plusses. It may have been for this reason that the old Micro Seiki introduced the flywheels that were accessories to its large air suspended tables, where the flywheel became a non suspended drag on the platter turned by an auxiliary belt around the platter. The flywheel would have caused the motor to put out more torque to turn the system on a constant basis causing less sensitivity to the drag of the stylus. Its just a thought but I have never lived with an air suspended table to make a direct comparison.
I believe J.C. Verdier wrote his own opinions that friction was a good thing as it required this extra output by the motor and all of his turntables, even his nouvelle platine, have an oil bearing even though it uses magnets to lower but not suspend the weight of the platter. Zero friction can cause the motor and platter to be effected by the stylus drag and in the case of low mass platters as used on the old DD tables, may cause a hunting for the correct speed in a reactive feedback loop from the speed servo, which caused some to walk away from DD drives, although I have found the best ones to have serious sonic plusses. It may have been for this reason that the old Micro Seiki introduced the flywheels that were accessories to its large air suspended tables, where the flywheel became a non suspended drag on the platter turned by an auxiliary belt around the platter. The flywheel would have caused the motor to put out more torque to turn the system on a constant basis causing less sensitivity to the drag of the stylus. Its just a thought but I have never lived with an air suspended table to make a direct comparison.