Abstract: In a system for compensating predictable periodic speed variations in the electric motor of a velocity servo, which speed variations may include variations at frequencies above the velocity servo bandwidth, circuitry is provided for generating synchronized reference signal frequency components corresponding in frequency to at least one ripple frequency component of the torque. Each of the synchronized reference signal frequency components is adjusted, while the motor shaft is revolving, in phase and amplitude in a sense to reduce the ripple at that frequency in motor speed. Both manual and self-adjusting embodiments are shown, each including real time spectrum analysis of motor torque to guide the phase and frequency adjustments.