Tables That Feature Bearing Friction

On a related point, one thing I've been wondering is why not integrate a flywheel with the motor pulley. For AC motors in particular this would have the advantage of smoothing out cog noise at the motor source, rather than pass it on to the platter(or an outboard flywheel) through the drive system. I know some of the older heavy-duty high-speed motors have some built in flywheel effect; it's surprising that this approach is not taken with some of the smaller motors in current vogue.

A flywheel can very well create problems if not done the right way.
It is only suitable to motors featuring a solid axis shaft and a very good and rigid bearing. The flywheel - if done the right way - add considerable amont of inertia to the motor shaft and to the whole moving system. Therefor it requires solid construction. Especially if the flywheel is directly attached to the pulley or part of it (which is the only way to use the inertia moment of the flywheel to smooth out most imperfections of the motor itself). The smaller motors envogue right now do not fare very well with flywheels.
The small motors common today have 3 big advantages. Even if all turntable-manufacturers using them do list some other advantages, it all comes down to these 3 only....:
1. they are inexpensive.
2. they are inexpensive.
3. they are inexpensive............

Dgarretson,

I addition to the practical difficulties that Dertonarm pointed out there are some good theoretical reasons against using a flywheel at the motor. In all motors motion is produced by magnetic attraction. When there is no drag the
magnetic fields in the stator and rotor will be perfectly aligned. When drag is applied the magnetic fields pull apart and the attraction creates torque. This is a very desirable characteristic in that torque is almost instantly created in response to a load perturbation. I say almost instantly because the rotational inertia in a motor delays the delivery of torque. Any delay in torque delivery adversely affects the motors ability maintain constant speed because the corrective torque is being applied after the fact. The longer the delay the worse the problem becomes.

Belts, particularly stretchy ones, have the same effect. They filter cogging, but also delay delivery of torque. Filtering cogging is a good thing, but it comes at a price. In many cases the fix is worse than the problem. Much better to just start out with a motor that has low cogging.

In addition to the theoretical arguments there is plenty of empirical data that indicates that low inertia motors tend to sound better. That has been my experience.

BTW: Certus turntables use an eddy current brake. The braking force is much greater than what a belt drive mechanism can keep up with.

Chris

Hi Dan_ed, I do not use the Platine Verdier. Furthermore I do not see that I have refered in any way to the sound of the Platine Verdier.
Did I ?
My comment was about a construction feature of the Platine Verdier which was used in this turntable indeed for the very first time in this particular context.
BTW - I have listened to about every commercial turntable released on the market the past 32 years (and a few non-commercial TTs too...).
However - you would never read any comment from me regarding sonics about any current market product ever.

Ok, Dertonarm. I'm just wondering what you meant when you posted this.

The only turntable so far which did it right (i.e. - correct application of "friction" to stabilize movement AND to provide additional damping to the platter) is/was the old venerable Platine Verdier in its original form (pre-1992) of bearing (without the ball support).

Nobody else has gotten it right?