Method of and device for automatic bias control

摘要

A method of controlling a bias current required to record an audio signal on a recording medium includes the steps of: recording a test signal having a frequency component higher than a predetermined frequency on the recording medium and reproducing the recorded test signal from the recording medium; determining a reference amount of the bias current variation on the basis of the level of the reproduced test signal; determining a bias current variation characteristic of the recording medium on the basis of the reference amount; and varying the bias current in accordance with a level change of a high frequency component of the audio signal by referring to the bias current variation characteristic during a recording of the audio signal.