2020 update : JC Verdier La Platine

@mr_gray 

My apologies for the late response, experienced repeated failed attempts to log-in to Audiogon for the past five days. A shout out to Tammy at Audiogon who helped resolve this.

I have been reading with interest your new motor escapade,  very exciting. Would it be safe to summarize that because of the better and smoother speed control of the motor / LPS, the flow of the music is enhanced? If you do decide down the road to employ the SOTA system, it includes the Roadrunner active monitoring device. A magnets has to attached to the underside of the platter to pair with a sensor. @lewn has questioned whether the magnet discs of the La Platine might interfere with the sensor of the Roadrunner. I never reached out to Donna @ SOTA. And you need to build a housing for the SOTA motor. The Galibier motor is passive and comes in a completed package. It also  comes with a Teddy Pardo LPS while SOTA sells its own LPS as an add-on. 
 

I think we have passed the point of arguing about the merits of the original motor. Like you , I will keep the original motor.  But deciding which new motor path to take is still elusive.
 

BTW, the elastic 2mm round belt I had been using on the Jasmine snapped. I have gone back to the double knotted silk thread. With passive motor and silk thread, there is quite a severe speed adjustment required. I did not get it right on my first try. But now it is playing at 33.33 rpm. I now understand why there is a toggle on the original motor to switch between belt and thread. And with the SOTA being an active monitoring system, it will self-adjust to whatever belt material being used. Donna confirmed that the SOTA motor works with thread. 
 

DC vs AC motor is an issue that was covered briefly in earlier threads, but why AC? And @thekong why dual / three phase AC controller? While SOTA uses a three phase AC motor, Galibeir uses a three phase DC motor. 

@ledoux1238 , as far as I understand, a majority of belt drive TTs utilising AC motors use dual-phase motors. As the name implies, these motors require two signals of different phases (90° apart I believe) to drive the motor. The cheaper way to implement this is to use a phase splitting cap to generate the second phase signal to drive the motor. While this works, it is less smooth comparing to a dual phase motor controller, which generates the 2 different phase signals separately! Some top belt drive TTs, such as the Rockport Sirius II, the Final using by Dover, as well as Basis’ top models utilise dual phase AC controllers. Basis also offers their dual phase controller as optional upgrades for their lower models.

The TechDas Airforce Zero, utilising a 3-phase motor, actually has a 3-phase controller and three 50W power amplifiers (one per phase) to drive the motor!

@thekong 

The TechDas Airforce Zero, utilising a 3-phase motor, actually has a 3-phase controller and three 50W power amplifiers (one per phase) to drive the motor!

As you pointed out my Final uses both a sine and cosine wave generator preamplifier feeding a stereo power amp to drive the motor. As well as infinite speed adjustment on both speeds independently it has the provision to continuously vary the amount of torque supplied to the motor.

Originally it used Stax D80 monos to drive the motor, but since then I’ve used Bryston monos (custom) , Rowlands - each amplifier imparts its own sound. Currently I use an Onix Audio OA60 to drive the motor - it has a fully regulated power supply internally. Importantly because you are amplifying sine/cosine waves cables make a huge difference. I am using MIT Oracle interconnects and speaker cables in the wiring loom from controller to power amp to motor for my TT motor supply. The phase coherency superiority of these cables in the TT power supply are quite audible.

@dover do u reckon the SOTA motor and speed control unit would be worth having a crack at?  third price of galibier and ac sort of floats my boat.

@ledoux1238 nice to have the OP back in the thread.  in some ways i am beginning to idolise the sound (not functionality!) of the old motor.  the ac is so locked in it is a bit like a CD player.  with the DC motor, when the planets aligned, it was sensuous.  now it is utterly spectacular and i can really hear these artists and the system is doing a better job of projecting the sound possibly but maybe it is a little less.  all i really know is i want more progression.  i have had so much improvement and the sound now is so resolved and yet juicy with energy and incredible lifelikeness - a band being recreated to play the music - not the music being played back.  the la platine has so much to give! soon i will have cable risers and i will have new speaker plugs and this will pacify my need for improvement for a bit but i am getting very close to installing the fr64s for a spell and shaking things up.  

what i would really like to do is buy a wellfloat double for the turntable.  i think that could be really good.  but i also wonder if the more transparency i get the more i will hear the slight woodenness i am getting a whiff of (which might be the AC motor compromised as it is).

@thekong

While the quality of the three phase drive in the Techdas is certainly very good, a three phase drive utilizing a generator and three amplifiers is very common. Virtually every DD TT has this architecture, going way back to the 80s. Some of these, of course, are pretty rudimentary 

The prime reason for using a 3 phase motor is that, properly built and driven, it delivers virtually linear torque.  This because of the overlapping nature of three phases separated by 120 degrees. In contrast a 2 phase motor does not produce linear torque This is why they are common in belt and thread drives, where the torque peturbulations are at least partially reduced by the drive decoupling. They also cost less. 

Note, cogging due to stator pole piece design is a separate issue. This can be eliminated where slotless/coreless designs are used.