| 摘要 |
An input level adjusting circuit used for an input source switching section in an audio device such as a control amplifier comprises an input selector for selecting one of input signals from plural input sources and outputting the selected signal and also outputting information concerning the selected input signal, a level adjusting circuit connected to this input selector for adjusting the level of the selected input signal, a memory for prestoring input level setting offset amounts which are relative differences in an amount of level adjustment for the plural input sources, and a control circuit responsive to the information concerning the selected input signal applied from the input selector for reading out one of the input level setting offset amounts for the corresponding input source and controlling the level adjusting circuit in accordance with the read out input level setting offset amount. The level adjusting circuit is automatically controlled in response to the selection of the input source to adjust the level of the input signal and thereby maintain a constant output level regardless of difference in the input level.
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