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Re: transient test - Part II

"I can't really claim anything about how far down the hi order harmonics are with a measurement like this."

You can look at the THD residual waveform with the HP-334. This gives a good indication of the presence of high-order harmonics.

"By getting things really linear using lots of feedback in solid
state (or any other technology), it seems like similiar results
can be achieved (good sound)."

But using lots of feedback guarantees a wideband harmonic residue. Granted, it will be buried in the noise floor, but it's there. The question is, how far down does it need to go before it sounds like your amp?

"One thing I notice about the multiplication hump is that with
low feedback, the hi order harmonics are way way down."

But the added complexity is still there. The harmonics are just far down in the noise floor. Also, which harmonic is up or down will vary with device nonlinearity (quadratic, exponential, etc). Take a look at Baxandall's Fig. 2 for the BJT case (WW, Feb 1979). Look at the increase in H4 for a fractional amount of NFB. Big! So it depends not only on device nonlinearity but also on the phase of each harmonic. Granted, to see the full development we need to pass through the whole hump.

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