| 摘要 |
PURPOSE:To attain natural and rational listening sense and to evade contradictory feeling in listening by boosting a sound only when a sound volume is smaller than a degree of sound volume. CONSTITUTION:An audio control voltage is fed to a negative side terminal of an operational amplifier 6 through a resistor R1, a positive side terminal connects to a DC power supply an a resistor R2 is interposed between an output terminal and the negative side terminal. Thus, assuming a sound volume control voltage to a resistor R1 as Vin in a sound quality control voltage generating circuit 5 and the output from the operational amplifier 6 as V0, then only when the sound volume control voltage Vin is smaller than the DC voltage E, the voltage V0 is positive and the sound is boosted by a sound frequency correction IC2. Furthermore, as the sound volume control voltage Vin is small, the voltage V0 is larger and the sound boosting quantity is increased. Since the sound boost quantity is controlled in response to the sound volume, contradictory feeling in listening sense is evaded. |
