Eiron wrote:
I was looking at 'Audio Electronics' by the late John Linsley Hood this
morning
while waiting for the newspaper to arrive, and was amused by this:

" Experiments in the late 1940s suggested that the level of audibility for
second and third harmonics was of the order of 0.6% and 0.25% respectively,
and this led to the setting of a target value, within the audio
spectrum, of
0.1% THD, as desirable for high quality audio equipment.
However, recent work aimed at discovering the ability of an average
listener
to detect the presence og low order (i.e. second or third) harmonic
distortions
has drawn the uncomfortable conclusion that listeners, taken from a cross
section of the public, may rate a signal to which 0.5% second harmonic
distortion has been added as 'more musical' than, and therefore
preferable to,
the original undistorted input. This discovery tends to cast doubt on
the value
of some subjective testing of equipment."

So the SET set is right. single-ended valve amps are officially 'more
musical'.


The interesting thing there, is the statement that because it seems some
may prefer 2nd harmonics, this means that it "casts doubt on subjective
testing", not that it casts doubt on the validity of the measurement of
distortion :-)

In other words, the people who prefer the distortion are wrong, and they
should be ignored. And it clearly indicates that his goal was the
production of an amplifier that measured well, not one that people liked
to listen to.

--
Nick