I recall these guys were testing out a high power version for the 301/401,s and Thorens 124.
Checked out the Phoenix. It won't work because there is not enough clearance from the platter."
You may be talking about something else here. Every speed control I have ever seen, is an external box that you plug the motor into. Also, torque shouldn't be an issue. You'll still be giving the motor what ever amount of power it needs to run.
"Every speed control I have ever seen, is an external box that you plug the motor into"
The Phoenix is different because it uses a small magnet that you put underneath the platter and then a small pcb card between the platter and the plinth so it can read the magnet, kind of like a strobescope.
The VPI might work, as long as it sends out AC, correct?
I am surprised that no one has come up with something like this for idlers. I mean, they make every audio gimmick in the book now, and this no gimmick but a real need; weird.
So, I did some more research on various forums and got some good information.
First, the Nott wave mechanic or VPI SDS will not work because they are for 7 watts and the 124 needs 15. Second, some people have indicated the stepping down the voltage to around 117 volts is advisable because the 124 was made for that voltage not the 123-5 that we know are given. Also, that to regulate the voltage is a good idea because of the voltage swings through the wall (that is really not the case for me as it only drifts 1 or 2 volts at the most). Last, and most understandable is trying to get the best possible sine wave you can feeding the motor as it is asynchronous.
Does these points sound reasonable?
You don't need an external speed controller for the TD-124. IMO the best upgrade you can make to your Thorens deck is to replace the old analog controller board and neon strobe with a quartz controller and LED strobe from Keystrobe UK. The parts are very reasonably priced and the installation is very easy - no soldering required. It's invisible (once installed) and will work with virtually any plinth design.