PURPOSE: To decrease the malfunction greatly by providing more than one pair of coils connected to each other and furthermore securing switching the polarity of each of the paired coils via the switch.

CONSTITUTION: The two coil terminals forming record/reproduction head 4 are refered to as A/A' and B/B' each and then connected toward A-A' and B-B' to secure the in-phase for the two coils each other. Chnage-over switch 5 gives switching to the two coils connected in series to secure the same or opposite phase to each other. The diagram shows that switch 5 secures the same phase to be connected to record/reproduction amplifier 6. With change-over of switch 5, the coils feature the opposite phases to be connected to the output side of control signal generator 7. Thus the control signals are recorded in the opposite phase to the two tracks on magnetic tape 3.