VPI Motor Upgrade Kit

Second what Photon46 said. That's a good summary.

Several months ago HW offered to ship me a 300rpm motor to A/B on my Teres and post a review. That would have been fun and I accepted. It hasn't arrived yet, so I presume VPI's been busy making stuff for real customers.

Toddwj,
The Teres motor controller circuit is unique (AFAIK) because it maintains the speed of the platter (NOT the motor) at exactly 33 or 45rpm. To do that, of course, the controller needs to know how fast the platter is spinning.

A strobe disc on the underside of the platter is read by a sensor positioned 1-2mm below it. The sensor is connected to the motor controller circuit via a cable that runs down through the plinth and out to the motor.

Full info and details of this ingenious design are on the Teres website. AFAIK all other controllers measure the speed of the motor, rather than measuring what we actually care about.