As a direct-drive motor rotates, there are action/reaction forces set up between the platter and base (cabinet), and between the motor rotor and stator. These lead to tonearm vibrations which cause poor sound reproduction. This paper describes how these forces can be minimized by adding a second motor or torque generator. The main drive motor and second motor or torque generator are driven in reverse phase, which greatly reduces base (cabinet) vibration in the rotational plane. This technique provides a substantial improvement in tonal quality.
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