
90 Analog Electronics
present, resulting in a multitude of intermo-
dulation products as well as third, fifth, seventh
etc.
harmonics, which explains why even quite
small levels of crossover distortion sound so objec-
tionable.
We have dealt at some length with non-linearity,
which gives rise to waveform distortion; the next
variety of distortion can be disposed of relatively
easily. In fact we are so used to it and find so little
to object to in it that it is frequently not thought of
as distortion at all. I refer to frequency distortion.
An amplifier may be perfectly linear in the sense
that the ratio of output to input voltage is indepen-