PURPOSE: To reduce gradient flutuation of sawtooth form wave and rotational fluctuation of a player by giving temperature characteristics to a constant-current source and compensating the temperature characteristics of a system in an acoustic player.

CONSTITUTION: By turning on and off a transistor 4 by a driving circuit 6 intermittent torque is let to occur to a rotor magnet 3, the altermate voltage synchronized with the rotational speed generated by a winding coil 7 is converted into pulses by a limiter 8, a generator 9. The pulses are supplied to an f-V convertor 10, control voltage is given in inverse proportion to the speed, the driving circuit 6 is controlled, and speed control is conducted. At this time temperature coefficient is given to the constant current which runs in a transister by a diode 31, resistors 32, 33 in the convertor 10, the temperature coefficient of the rotational speed fluctuation of a motor is corrected, the gradient fluctuation of saw tooth form wave generated in response to the output of a circuit 9 is reduced and the rotational speed of the magnet 3 is stabilized.