Treadmotor speed control for power supply.

I just recently bought a couple treadmill motors and a couple
controllers. They also have a controller listed as 130DC 8A Power supply.
At $35.00 I thought I might give it a try, along with one or two large
Caps, for a stepper drive supply. My thought goes to using a multi turn
pot that can be locked to limit the output to 75V. Add the electrolytic
caps and It should work. Right?? The only thing I'm not sure about is the
pulse width and frequency coming out of the supply. Might it be a little
to course to filter down with Caps?. Sure wish I still had access to a scope.

Don