Refers to that because the power amplifier is not perfect, the output signal not only contains the amplified input audio components, but also produces some frequency components (harmonics) that are 2 times, 3 times, or even higher than the original signal, so that the output waveform is not the original Look like. This kind of distortion caused by harmonics is called harmonic distortion.

A distortion phenomenon peculiar to Class B amplifiers is caused by the amplifier characteristics of the circuit. The reason for this distortion is that the positive and negative half cycles of the signal are amplified by two different sets of devices (power amplifier tubes, etc.), and the waveforms of the positive and negative half cycles cannot be connected completely smoothly.

The opposite of high fidelity, that is, the output sound of the power amplifier is stained with some characteristics that the input music signal itself does not, such as singing in the bathroom, the kind of sound produced is a typical sound dye phenomenon. Some components are added (or reduced) in the reproduced signal, which is the so-called sound staining phenomenon, which of course is also a kind of distortion.