[Nick Gorham]

Ian Iveson wrote:


Extending analysis in that direction, dynamic changes in
output impedance, and hence in DF, will lead to dynamic
variation in the amplitude of SPL variations with frequency.
Can that be called distortion? What about the consequent
IMD, arising from both the speaker and the output stage?
That would not be part of the usual measured IMD of an amp
with a sine wave and constant load, I suppose.


A lot of work was done in the 1950s with regard to DF and output
impedance, there seems to have been a period where amps were produced
with variable DF, ie +ve, zero and -ve output impedances. Maybe you
should read some of the papers from that period, they were far from
groping in the dark.

--
Nick