The loudspeaker using continuous revolution of an ultrasonic motor (USM), proposed by the authors, is suitable to radiate sound of very low frequency. This paper describes an improved model of the USM loudspeaker. Functions of rotor and stator is inversed than the first model to simplify electric connection. Mass of the rotating ring is increased to make the inertial force larger. Silicon rubber joint is used to connect USM and the cone radiator to avoid frictional noise.
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