> (Tom)At idle, a class AB amplifier is in class A so it indeed is linear
Agreed, Tom. We're more in agreement than otherwise. My point is that, given
sufficient excitation, a nonlinear system in general can exhibit a
self-sustaining oscillation. The "sufficient excitation" bit is what brings
the nonlinear behavior into play.
>
> Class A is the point of highest gain.
For small signals, yes. For large transients of arbitrary shape, that would
be hard to prove. The stability of nonlinear systems is very difficult to
evaluate. Generations of engineers, physicists, and applied mathematicians
have spent their careers on the subject. And it isn't just an academic
exercise either. I recall chaos being a real problem in some experimental
parametric amplifiers that some folks were working on back in the early
`80s.
>.
> A PA [won't] suddenly
> turn into an oscillator that develops so much saturated current it
> explodes.
Whether or not they turn into oscillators, it appears that they do explode
from time to time!
Regards,
Carl
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