For Basis TT owners does the VPI SDS work?

With the Walker, I noticed a surprising degree of improvement on my Notts Hyperspace. Musical instruments were much better separated in space. Vocals were cleaner. The position of the phase switch on the Walker made a huge difference. I was very surprised on both counts. I was a sceptic beforehand. I am now using the Walker on my Lenco. It's perfect for the Lenco or Notts motor, because they're single-phase. At least I see/saw no phase-splitting capacitor in or on either motor.

A single-phase AC controller would still work to control speed of a synchronous motor. Proof of that is the fact that the Walker and SDS controllers do work with all such motors. But you are correct that a controller that could supply two sine waves that were 90 degrees out of phase would be more ideal in terms of noise reduction (and cogging, I think). The Basis unit looks nifty but it costs quite a bit. I see where Allnic has a tube-based controller, also very expensive.