Guitar Amplifier Electronics: Basic Theory

Guitar Amplifier Electronics: Basic Theory

Richard Kuehnel

Our new book uses these calculators to design preamp stages, cathode followers, tone stacks, power amps, phase inverters, negative feedback, and power supplies.

calculatorLaunch me!

guitar amp grid-stopper resistor circuit

What does this calculator do?

The grid stopper resistor RGS blocks radio frequencies while allowing audio signals to pass. This keeps the amplifier from becoming a radio receiver and prevents the stage from breaking into parasitic oscillation. Large values can be used to attenuate treble and improve the dynamics of overdrive.

The frequency response for a given resistor value depends on the output impedance that drives it, the inter-electrode capacitances of the tube, and the voltage gain that it achieves. The calculator plots gain versus frequency based on these factors.