Duty-Cycle Modulation

For class A tube amplifier simulation, there should be level-dependent duty-cycle modulation as a function:^10.3

• 50% at low amplitude levels (no duty-cycle modulation)
• 55-65% duty cycle at high levels

A simple method for implementing duty-cycle modulation is to offset the input to the nonlinearity Eq.(9.5) by a constant, such as input RMS level times some scale factor.