Noise analysis of ferrite head in audio tape recording

Mechanisms of the generation and the control of magnetic head noise in an audio tape recorder were studied. Head noise was generated from some flux changes by 180° domain wall movements which were produced because of relaxation of shocks given by a frictional vibrating tape. Then noise spectrums were based on vibration spectrums of a tape. Low noise property of a permalloy head was due to large eddy current losses which were accompanied by restrictions of domain wall movements. On a ferrite head noise, effects of crystalline anisotropy and distortion were great, however, a low noise ferrite head was not presented until shape anisotropy and pinning effects by the grain boundary or SnO2precipitation were applied.