Hello, Looking For A new Preamp

The point I was making about the Rega decks was more about isolation rather than it being so terrible using stepper motors.

A proper stepper motor is used for positional accuracy on such as CNC driller routers. I once had a Dorniver Micromat for drilling and routing PCBs. The type of stepper motor used by certain turntables would have been far from accurate for such use.

See post: https://www.hifisystemcomponents.com/forum/turntable-speed-control_topic4359_post54685.html#54685

As I have stated, the steps can be felt when the pulley is "rolled" between finger and thumb, but commutating which is similar is also felt with DC motors. In fact, motors are difficult things altogether.

In all fairness, these little tin-can steppers could be the way to go provided the vibration could be isolated, and there are a number of turntables which use pod mounted motors in a bid to isolate them from the main table.

I have recently been working on such a proprietary turntable. Although it has to be spun up to start, the resulting bass is more "wholesome" than that from my Planar 3 (no matter which version of modification).

My next Planar 3 mod is to provide it with an isolated motor pod, but that involves making an 80mm diameter hole through the motor board.

If I can find the original glass platter out of the loft I will be able to photograph the way it is set up and publish it somewhere on the forum.

If this achieves the bass quality I'm after I will let you all know.

Interesting topic.
Rega's top turntables, such as the old P9 & now the P10 use a DSP controlled motor PSU
which they say is tuned to the specific motor used in the deck to reduce vibration -
would this be an introduction of a + or - dc offset to the AC - or something else?
Having owned a P9 - it is a very good turntable but does need good isolation & mounting
away from speakers. The tonearm would often wobble in time with kick drums with high volume
rock.

As Graham said, the DSP aspect of these units offered by Rega and others is usually a microcontroller recreating a sinewave to drive the stepper motor on the TT. They often supply two outputs of the sinewave phase shifted by 90deg to drive the two winding on the stepper motor. "Fine tuning" for each motor is done by adjusting the phase difference between these two outputs to achieve the lowest vibration level for the specific motor its connected to.