Solid state electrical musical instrument amplifier

A solid state distortion circuit for use with an electrical instrument amplifier, comprising an instrument signal input means;

• a preamplifier having a feedback loop;
• distortion means connected in parallel with the feedback loop and having nonlinear resistance versus applied voltage characteristics over at least a portion of its operating range immediately below a preset voltage;
• means in association with said distortion means for limiting voltages applied to such distortion means to below said preset voltage and causing said distortion means to operate at least partially in said nonlinear portion of its operating range so that said preamplifier compresses the peaks of the input signal and provides a distorted output signal which substantially preserves the relative even and odd harmonic content of the input signal;
• and signal output means.

A solid state electrical instrument amplifier comprising an instrument signal input means;

• a preamplifier;
• a variable band reject filter for attenuating a variable frequency band of the signal from the preamplifier, the reject band of the filter being controlled by controlling the resistance of two photoresistors in such filter;
• a sweep rate generator in association with at least one light source so that the output of the sweep rate generator is represented by a variable light output of the light source and said light source being physically arranged in association with the photoresistors so that light from the at least one light source falls upon the photoresistors to control the reject band;
• means for combining the signal from the variable band reject filter with the signal from the preamplifier in selectable propotions;
• and signal outputs means.

A solid state variable band rejection filter for use with an electrical instrument amplifier, comprising an instrument signal input means;

• a preamplifier;
• a variable band reject filter for attenuating a variable frequency band of the signal from the preamplifier, the reject band of the filter being controlled by controlling the resistance of two photoresistors in such filter;
• a sweep rate generator in association with at least one light source so that the output of the sweep rate generator is represented by a variable light output of the light source and said light source being physically arranged in association with the photoresistors so that light from the at least one light source falls upon the photoresistors to control the reject band;
• means for combining the signal from the variable band reject filter with the signal from the preamplifier in selectable proportions;
• and signal output means.