Linear range
The linear range is that range of input or output values for which an electronic amplifier produces an output signal that is a direct, linear function of the input signal. That is, the output can be represented by the equation:
When operating in the linear range, no clipping occurs. If an amplifier were perfectly linear, no distortion would occur.
Vacuum tube amplifiers tend to exhibit soft clipping; as they approach the maximum possible output value, the gain tends to drop, rounding the tops of the signal waveform. Transistor amplifiers, by comparison, tend to produce hard clipping; the gain remains approximately the same until the maximum possible output voltage is reached; at that point, hard clipping occurs and the waveform never exceeds that value. The sharp inflection points thus produced in the output waveform tend to have many more high-order harmonics. This is alleged to be the basis of the "transistor sound" that some audiophiles find offensive.
