The elementary nonlinearities discussed above are aimed at approximating the sound of amplifier distortion, such as often used by guitar players. Generally speaking, the distortion characteristics of vacuum-tube amplifiers are considered superior to those of solid-state amplifiers. A real-time numerically solved nonlinear differential algebraic model for class A single-ended guitar power amplification is presented in . Real-time simulation of a tube guitar-amp (triode preamp, inverter, and push-pull amplifier) based on a precomputed approximate solution of the nonlinear differential equations is presented in . Other references in this area include [338,228,339].