Patent ID: 8686792

Claim:
An amplifying device which amplifies an input audio signal input to the amplifying device to outputs a sound, the amplifying device comprising: a signal delay processor that outputs the input audio signal with a predetermined time of delay; an amplifier that amplifies a signal output from the signal delay processor; a voltage variable power supply that supplies a power to the amplifier; and a supply voltage controller including: a simplified envelope creating unit that calculates an envelope of the input audio signal, a read-ahead update unit that generates a read-ahead signal, and a supply voltage control signal creating unit that generates a supply voltage control signal, wherein: the read-ahead update unit generates the read-ahead signal indicating a specified time delay based on a comparison between the envelope and the output voltage of the voltage variable power supply, the time delay being decreased when the output voltage of the voltage variable power supply is greater than the envelope, and the time delay being increased when the output of the voltage variable power supply is less than the envelope, and the read-ahead signal controls the supply voltage control signal creating unit to generate the supply voltage control signal with the specified time delay to follow the envelope of the input audio signal, and output the supply voltage control signal to the voltage variable power supply.