| 摘要 |
PURPOSE:To improve the S/N through variation of the high-band cutting amount by giving the control to the differential amplifier via the control signal which is produced in accordance with lowering of the field intensity. CONSTITUTION:Control signals t1 and t2 feature the relation as t2=A-t1. And t1>>t2 is satisfied in case the field intensity is high, and t1 is decreased with lowering of the field intensity. The value becomes approximate to each other between t1 and t2 when the field intensity is small, and thus transistors 24 and 26 start to conduct. Then the high-band cutting main channel signal which is applied to the base of transistor 33 from stereo composite signal input terminal 18 via high-band cutting circuit 32 is begun to be led out to the collector of transistor 26. Thus the cut signal mixed into the output signal is delivered along with the uncut main channel signal which is led out to the collector of transistor 23. And the ratio between these two signals varies smoothly in accordance with the field intensity. |
