| 摘要 |
PURPOSE:To obtain optimum effects at both stereophonic broadcasting and monaural or multiplex broadcasting times, by automatically switching the size of a difference component for acoustic image enlargement in corresponding with the broadcasting mode of received signals. CONSTITUTION:At time time stereophonic broadcasting a high-pass filter has no effect since it is short-circuited and the effect of a low-pass filter becomes smaller since a resistance 12 is inserted. Therefore, (-L) signals are inputted to one input of a differential amplifier circuit 39 and (-R) signals to the other input and the difference components of (L-R) are outputted as the output of the differential amplifier circuit 39. These difference components produce acoustic image enlarging effects. In the case of monaural broadcasting, L- and R- signals are respectively passed through the high- and low-pass filters by turning off a switch 36 and short-circuiting another switch 37 and phases of the L- and R-signals can be changed by frequencies. Therefore, by inputting each signal to the differential amplifier 39, the difference component of (L'-R') can be fetched. This (L'-R') difference component can produce an acoustic image enlarging effect. |
