| 摘要 |
PURPOSE:To realize high-accuracy linearity by controlling a compressing characteristic or an extending characteristic in a low-level area to an amplifier whose gain is controlled corresponding to a signal level in a main signal route. CONSTITUTION:A first amplifier installed at the main signal route amplifies an audio signal in the case of recording or reproduction passing through the main signal route. The output signal of this amplifier is controlled the passing band or the frequency characteristic by a filter. The audio signal passing through the filter is converted to a control current by a voltage/current conversion circuit 48 after detecting the level by a detection circuit 46. According to the control current, the gain of a second amplifier CCA 36 is controlled. A characteristic control circuit 50 controls arbitrarily the compressing characteristic or the extending characteristic in the low-level area to the CCA 36 continuously according to a control input from the outside. |
