| 摘要 |
PROBLEM TO BE SOLVED: To more effectively express a timbre change (compression feeling) due to distortion by controlling the power source voltage to be supplied to an amplifier according to an input signal level by performance of a musical instrument. SOLUTION: An audio signal inputted to an input terminal 10 by performance of musical instruments is branched into two routes, and one of them is amplified through a first amplifier 12, a variable resistor 13, and a second amplifier 16 and is outputted from an output terminal 18. On the other hand, when a switch 20 is turned on, the other input signal is inputted to an amplifier 22 through a switch 20 to be amplified. And, the amplified input signal is inputted to an envelope extraction circuit 24 to extract the envelope. The envelope value thus extracted is inputted to a power supply voltage control circuit 26 and a power supply circuit 28 is controlled by the power supply voltage control circuit 26 is according to he envelope value, and the power supply voltage to be supplied to the first and second amplifiers 12 and 16 are controlled according to the level of the input signal. |
