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Tables That Feature Bearing Friction

I recently had the opportunity to audition the DPS turntable which, unlike most tables, has a certain amount of friction designed into the bearing. This, when paired with a high quality/high torque motor, is said to allow for greater speed stability--sort of like shifting to a lower gear when driving down a steep hill and allowing the engine to provide some breaking effect and thus greater vehicular stability. I am intrigued by this idea and was wondering what other people thought about this design approach. Are there other tables which use this bearing principal? One concern I have is that by introducing friction you may also be introducing noise. Comments?
128x128dodgealum
lewm
13,049 posts
 
I don't know of any direct-drive tables that deliberately use this strategy, except possibly in their electronics. Can anyone think of any?
mosin
410 posts
 
Lew,

Yes, there are direct drives that do it, although it may be a happy accident for some. By centering mass in the platter, some direct drives avoid excessive noise from their motors. As a result, they also introduce a better way to handle inertia. By my way of thinking, using inertia properly is key to the conversation, so in that sense, a lot of direct drives succeed.
lewm
13,049 posts
 
Come to think of it, Win, I see your point. I observed the herky jerky movement of my SP10 motor without the platter. It almost threw itself off the benchtop where it was sitting. So clearly, the mass of the platter smoothes out the operation. Further, the mass of the platter is constrained to within certain limits, if a servo dd table is to operate well. Of course, that is quite different from an eddy current brake, but the principle is perhaps similar. I just had not thought of it that way.
dougdeacon
3,338 posts
 
Lew,
Chris Brady's Certus DD designs are said to implement this principle very thoroughly, as does his Verus rim drive, both due to the the motor design.

His belt drives used bearing design and choice of lubrication to achieve a similar effect (as do the similar designs from Galibier and Redpoint). Bearing noise on any of these is nonexistent in any system I've heard, including mine. Motor noise transmitted through the belt, while very low, is more audible than that.
dertonarm
1,042 posts
 
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). Its a true eddy-current brake applied on a large diameter and fairly strong. The large diameter provides excellent damping on the turntable platter itself (which however was only a side-effect of the vertical bearing being suspended by magnetic force). Somehow archaic in execution, but very effective indeed.
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