verdier Platine or Nottingham Analogue hyperspace

@lewm, Thanks for the SOTA tips. I have been been looking at options for the stock motors ever since my latest system upgrades, Eminent Technology LFT-8b and a pair of Von Gaylord Nirvana 130W tube amps. The fluctuation in speed has become audibly disturbing on several records. And looking into replacement motors was, I thought,  the way to go.

However, Rudolph Ploeger of Callas Audio made a strong case of sticking with the stock motor with modification, hence my query. Frankly, I am quite uncertain which way to go. Perhaps as @ct0517 noted, a lot of misinformation with the PV's. I will PM a.s.a. I post this.

SOTA sells a 3-phase AC synchronized motor plus the drive amplifier plus an outboard tachometer that feeds back to the drive amplifier, as an all in one kit, called the Eclipse. That’s what I’d suggest for the Verdier.

Would work for the Notts too.

@lewm  I have revisited the SOTA website. This is a serious option. SOTA has a licensing agreement with Phoenix Engineering to use their PSU and Roadrunner since 2019. I think it was unavailable for a couple of years prior to 2019. I had been searching for one since 2018. Great news indeed. Thanks again!

In the meanwhile, I am working with @ct0517 to set up the thread drive properly. There seems to be a few fundamentals that I have over -looked.

Here is some useful information about the Platine Verdier motor (J.C.Verdier, The Manufacturers’ corner, SOUND PRACTICES - Issue 11):

"... First of all, let’s approach the question of the motor. Certainly, I use a motor marked Philips, a name that could make one think of an ordinary motor, because that big European trademark is very prominent in the mass market for consumer goods.

That is misleading, because Philips is also very involved in very advanced technology. The motor used in the Platine Verdier is produced by a special branch named "Philips Technology". The motor is certainly not an ordinary part - given that the price is 2500 FF for one unit in the shop of the the French distributor! That is not exactly a gift for a motor of diameter 40mm and 50mm high. It must have something very special inside. Let us see:

First af all, it is "low inertia" motor. In the case of Philips unit, that term refers to a very special technology. In "low inertia" motor, the turning part-the rotor-consist of a cooper coil, the turns almost parallel to the rotation axle cutting the field lines of the magnetic circuit, excited by a permanent magnet which is totally fixed. The weight of the rotor is reduced as much as possible, so the inertial tendency is small relative to the work provided by the motor.

I must say that I don’t think that low inertia in itself is that interesting of a quality for turntable’s motor. It can even be a deficiency for players with relatively light platters, as indicated in my discussion of the value of mechanical braking below.

Another quality of the low inertia motor is much more interesting and relevant to the issue at hand: its rotation speed depends directly on the DC voltage. A simple integrated circuit regulator such as an LM 338 is enough to obtain perfect stability of the speed.

Let us come back to the motor description: The magnets are very powerful in a small package. They are metallic alloy (nothing like cheap ceramic magnets). The collector and the brushes are gold plated to minimize the resistance of the contacts.

The axle of the motor turns in fitted and self lubricated bronze bearings, its diameter is 3mm. When the motor is powered at its nominal voltage of 12V, we hear the rubbing of the brushes on the collector. It requires a very small environment to be able to hear this small noise.

In the Platine Verdier, the actual voltage applied to the motor is 3V for 33 RPM and 4V for 45 RPM. At those low voltages, it is necessary to pres your ear directly on the motor to hear the commutation sound..."