| 摘要 |
PURPOSE: To generate crossover distortion for emulating desired compression accompanying a vacuum tube amplifier by applying an excessive bias to an offset in an input circuit by a charging element when an input signal is larger than an input clipping element. CONSTITUTION: An input signal is inputted to an upper operational amplifier circuit 110U through a resistance 112 and a capacitor 114. This signal is applied to an output diode 126, which is biased into a large-quantity forward conductive state by zero crossing because of an excessive bias. Therefore, the negative amplitude is clipped by the diode 126 to clip the part of a positive-potential side amplitude as the excessive bias. This signal is a semisine wave which is partially clipped in the positive potential direction and a semisine wave which is clipped completely in the negative potential direction and asymmetrical. A lower operational amplifier 110L, on the other hand, is quite the reverse of the upper one. The upper- and lower-side outputs are mixed 131 to obtain an output having considerable crossover distortion. |
