[R. Stanton]

On Nov 10, 12:26 pm, wrote:
(It was suggested that I bring my question over here....)

While so many people run around with their hands in the air talking
about this amp and that amp, their distortion measurements,
tube-vs-transistor, yadda-yadda-yadda, I'm concerned with something
much more fundamental.

If the phrase is true "all amplifiers cause distortion," which I
believe is the case, my question is simple...

How is it created?

For instance, let's take the scenario of an all-analog, all pure
class-A staged amplifier.. My *assumption* is that in an ideal model,
this scenario would generate no distortion, but in using real-world
components, distortion is still generated.

I understand that there exist what are called "nonlinearities" in the
amplifier, where at some input levels, a change of the input voltage
causes a particular change in the output voltage, but at some other
input level voltage, the same change in voltage (just offset from the
original) would cause a different amount of change in the output.

So is distortion's root this nonlinearity?

And if so, why does this nonlinearity always manifest itself as n-order

harmonics?


You asked why one can't put a 100 Hz sinewave into a some kind of
nonlinear device and get out 100 Hz + 105 Hz.

A steady (reoccuring) wave is composed of a fundamental (sinewave) and
various harmonics. (In a reoccuring wave, every cycle looks exactly
like the previous cycle.) If there was a non-harmonic frequency
component, such as a 105 Hz , added to 100 Hz, the sum of the two waves
would vary in amplititude as the two components went in and out of
phase. That would be a non-reoccuring waveform.

Puting a sinewave into a any nonlinear amplifier can only produce a
reoccuring output waveform. Such a wave will always be composed of a
fundamental and harmonics. No matter how much an amplifier bends and
distorts the sinewave, the output wave will always be a constant
waveform. Thus, it must be composed of a fundamental and various
harmonics, only.

Bob Stanton