| 摘要 |
PURPOSE:To obtain the sufficient distortion decreasing effect even when the speaker is at any position by measuring the impedance characteristic of the speaker, adjusting the impedance characteristic of the impedance equivalent device so as to come to be the impedance characteristic equal to the measured impedance value and feeding back the distortion component only in a negative way by the comparator. CONSTITUTION:The impedance of a speaker 7 is measured. The terminal connected by a changing-over switch is set to an A side, and the signal for measuring the impedance is added. For the impedance measuring signal, the sine wave is used. The driving electric current to flow at a speaker 6 is detected as the terminal voltage of an electric current detecting device 8, the voltage value is measured by an impedance measuring circuit 10 and the impedance is obtained. The impedance of the speaker is changed by the setting position of the speaker. |
