| 摘要 |
PURPOSE:To obtain the very natural audible sense characteristics, by providing an amplifying circuit for either one of a signal through a phase shift circuit and a direct signal. CONSTITUTION:An intermediate frequency signal applied to an input terminal 1 is amplified at an intermediate frequency amplifier 2 to a level required for the detection. The output signal is divided into a direct signal and a signal through a phase shift circuit 3, the signals are multiplied at a multiplying circuit 4 to obtain a desired output through a low-pass filter 5. For example, the provision of an amplifier 7 at the prestage of the circuit 3 tentatively suppresses the reduction of input signals to the multiplying circuit 4 and the rate of reduction of the output signals is taken as the same gradient as that of the input level around a part where the effect of the reduction on the input signal takes place, allowing to suppress the rate of reduction to a root of that of the conventional circuits. Thus, the unnatural disappearance of sound generated at the reduction in input signals can be eliminated, allowing to obtain the very natural audible sense characteristics. |
