| 摘要 |
PROBLEM TO BE SOLVED: To provide the low-frequency sound and high-frequency sound emphasis device of simple constitution by approximately adding the characteristics of secondary low-pass and high-pass filters in an operational amplifier. SOLUTION: A composite filter is constituted by overlapping the secondary low-pass filter comprising resistors R1 and R2 and capacitors C1 and C2 and the secondary high-pass filter comprising the resistors R3 and R4 and the capacitors C3 and C4. Acoustic signals from an input terminal Input are passed through the operational amplifier OP1 after being passed through the composite filter and are outputted to an output terminal output. In this case, impedance in the passing area of an element for constituting the high-pass filter and the low-pass filter is set to a value for reducing influence by the impedance of a component on the other side from each other. Since the gain of an amplification stage comprising the operational amplifier OP1 is determined by the ratio of the resistors Rf and Rg, by constituting the resistor Rg by a variable resistor for instance, the emphasis degrees of a low-frequency sound part and a high-frequency sound part are simultaneously adjusted. |
