Jonathan Palmer considers his designs as holistic, to be taken in its entirety, and not really appropriate to break down into specifications. In his design philosophy, the drive system is not simply a motor - the motor, housing, belt, pulley, platter, plinth, mat, main bearing etc as all these items have to combine harmoniously to realize the results he is looking for. It is a system after all.
He uses AC synchronous motors which may be somewhat unfashionable these days. But AC motors are very good timekeepers, and being used to accurately power clocks and medical equipment is surely a fine indication of their performance. They rely solely upon the frequency that they are provided with and cannot deviate from that.
A DC motor needs a feedback loop to tell it to either go faster or slow down. However, it can only be told to do this once the error has occurred and so may be in a constant state of change however small.
The power supply outputs only the necessary amount of power required to maintain the constant stable rotation of the high mass platter. Anything more than this is considered as simply "noise".
"Like a fine watch movement, it is a delicate balance that provides a state of harmony between the drag and inertia.
Starting a palmer turntable requires you to interact with it, much like winding a mechanical watch It soon becomes second nature to spin the platter with just the right amount of force so that it is running to speed instantly.
So then, an Holistic approach to turntable design, every component is considered in how it interacts with its neighbor so that the sum of the parts is exceeded by the whole."
The palmer 2.5 likewise sports an extremely massive billet aluminum platter, a compressed birch veneer plinth, and a very well isolated AC synchronous motor. Classic British made analogue product and sound.