Pooh Bear wrote:
Bret Ludwig wrote:

Arny Krueger wrote:

An experienced eye ( such as mine ) can interpret the waveform rather
well.

This is bull**** incidentally. Oscilloscopy is not the tool to track
down non-gross distortions, at least not directly.

You incorrectly attributed that comment.

It was mine ! And I stand by it ! Very much so in fact.

Examination of the distortion analyser output waveform shape is highly valuable
with regard to getting a feel for the harmonic content and indeed any specific
linearity issues. Crossover artefacts are very obvious too. You simply 'get an
eye' for it.

You *could* use a spectrum analyser to get the numbers but a waveform on a scope
take some beating for instant 'readability'.

I guess 25+ yrs of doing this for real as a design professional gives me the
advantage over the casual newsgroup junkie !

You must have a really big scope tube and some hellacious deflection
amplifiers to drive it or else eyesight far beyond mortal
man....Viewing the residual distortion from a spec an or a tuned filter
can be very useful, but raw waveforms have to be fairly gross before
much can be seen of them. I would say that the dynamic changes from a
signal changing in amplitude or pitch might be useful, but generally
you see generator artifacts more than anything else.

Oldtimers did everything with scopes in x-y mode or free running
y-time because that's all they had. The availability of good triggered
sweep two channel scopes and now distortion and spectrum analyzers at
relatively hobbyist-friendly prices has made us all lazy. But a scope
can tell you if you have 20% or one percent thd: much beyond that it's
hopeless.

Not that thd means that much....