| 摘要 |
PURPOSE:To attain loudspeaking without distortion by providing a reference voltage section to a power supply and detecting and displaying an output of a power amplifier so as to display the maximum output level and adjust an input signal source. CONSTITUTION:The reference voltage generating section is provided to the power supply of the power amplifier 2 to light a display element by the result of comparison between the reference voltage and the output voltage of the power amplifier 2. If a power voltage (-Vcc) of the power amplifier 2 is fluctuated, since the voltage of a reference voltage diode 7 and an emitter voltage of a transistor 5 are fluctuated similarly, the maximum output voltage of the power amplifier 2 is detected by the voltage setting of the reference voltage diode 7 and the maximum output voltage is displayed independently of the fluctuation of the power voltage. Further, the display device is lighted by clipping, then the sound is subjected to loudspeaking without distortion by the level adjustment.
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