Tables That Feature Bearing Friction

It's not a new idea. The Garrard 301 used an "eddy current brake" in much the same way. The degree of braking was used to fine adjust speed, but it also stabilized the speed. Don't know of any other "modern" turntables that do this, though.

I know of one. ;)

Basis, Galibier are two that I've noticed having a bearing with more drag than one might otherwise expect. I expect there are others but these I have first hand experience with. If you spin these bearings with no platter they don't turn very many times. Add the platter and they spin a few more times before stopping. I would also think in the case of these two bearings that it is the tight tolerances and oil viscosity that provide this resistance.

I think of this as being a bit different than eddy current breaking, but it is hard to consider the bearing a table uses without also considering how the platter is driven. (BTW, in addition to Mosin, I understand Teres is using eddy current breaking in their DD tables and maybe in the Verus drive. But I'm not sure about the Verus.) As one can imagine, motors with differing degrees of torque may work better with a bearing with a bit more or less drag. It gets even more interesting when different belt materials are added to the system.

In contrast I recall stories about Walker tables and how they will spin a long, long time on that magnetic field bearing. I don't know what Walker uses for a motor, but I would expect that it is a very low torque motor.

The point I'm trying to make is that you have to take the drive system on any table as a whole. There are many designs possible to get to a solution.

Basis, Galibier, Teres, Redpoint, Mosin's Saskia, Garrard, probably many others. Chris Brady wrote an effective explanation of how a carefully chosen amount of steady-state drag (from the bearing, an eddy current brake or otherwise) can minimize the effect of variable drag events (i.e., stylus drag). Check the Teres website, it's on there somewhere. The concept is that if the motor is working against a high steady load, the proportional value of any stylus drag event is reduced. That makes it easier for the motor/coupling system to overcome. If a table shows the motor/coupling system little or no load, each stylus drag event is proportionately much greater and therefore more likely to be audible.

Having heard most of the tables mentioned above, my ears agree that the theory has merit, always depending on execution of course - as Dan said. It certainly works with Mosin's table, brilliantly.

Hey Doug,

Call me Win. I'm trying to outlive the "mosin" moniker, but without much luck. ;)

Anyway, Chris did give a great explanation, and there are various implementations of it. Even sheer mass at the platter can help when the bearing arrangement is designed with braking in mind, but there are other implementations. Properly used, the motor itself can go a long way to controlling the spin. Also, Garrard (as you already know) used a grease bearing very effectively as a dynamic brake. The list goes on, but the most important thing is to make sure the turntable has no runaway effect, or that it is not bogged down anytime during its operation. Free spin equals loss of control, in my opinion.

Best,
Win