| 摘要 |
<p>Conventional pre-amplifiers for electric guitars use an operational amplifier (OA) with a volume control in the feedback line, together with back-to-back diodes (D1,D2) to limit peak amplitudes. If the amplifier has a high input impedance, the diodes conduct when a string is first struck, producing distortion known as fuzz, which is considered desirable by some popular music performers. The disadvantage of a high input impedance is that harmonics produced by the string are lost. The pre-amplifier circuit is modified so that it has a control potentiometer (P) which simultaneously varies the input impedance and the feedback resistance. The harmonics are thus audible when the control is at one end of its travel, and the fuzz effect increases as the potentiometer cursor is moved towards the other end.</p> |
