I am a bit curious about how something like the SDS and Walker work on a universal basis. The two phase motors in the Basis table have a capacitor to split the 60hz AC current and offset one part by 90 degrees. The Basis motor control eliminates the phase splitting capacitor (a capacitor is not ideal for splitting the phase) and essentially regenerates two completely separate phases. Hence, the motor itself has to be rewired to bypass the capacitor in order to make use of their motor control.
If the SDS and Walker do not require rewiring of the motor itself, it is creating just one pure ac current to feed the motor and relying on the phase splitting capacitor in the motor. If that is the case, there are two issues. First, the capacitor is not ideal for the job. Second, if the motor control changes speed between 33 1/3 and 45, the use of the capacitor is even LESS ideal. Speed change with synchronous motors mean changing the frequency of the AC signal. If the motor controller changes the AC frequency, the fixed value of the phase splitting capacitor will not be the correct value for the new frequency. In other words, one may still be better off moving the belt on the motor pulley than flipping the switch on the motor controller to change speeds.
I have not tried either the Walker or the SDS, so I don't know how they actually sound. I bet they do a very good job, as others have reported. So, I am raising theoretical concerns about the ideal way of doing speed control on tables with synchronous motors, assuming that the motor itself is not modified to use either. The speed control that Basis makes DOES require that the motor be modified to eliminate the use of the phase splitting capacitor.
