On Thu, 21 Oct 2004 20:17:46 +0300, "Iain M Churches"
wrote:



"Jim Lesurf" wrote in message
...
You can, of course, say the same about many individual technical specs
taken in isolation. Ideally, the amp should be 'adequate' or better on the
basis of a series of specs. This, in my experience thens to be what
mathematicians call "necessary but not sufficient" as a guide. i.e. if you
fail some specs you can expect the sound to be altered in predictable
ways.

In article , Iain M Churches
wrote:

As regards distortion, I have found that the amount of THD is not so
important as the distortion content - the way the THD is made up. For
example amplifiers with a small amount of 3rd harmonic sound less
pleasing than amplifiers with a larger amount of 2nd harmonic.

I have found that amplifiers with the most pleasing (this may not be the most
accurate:-) sound seem to have a harmonic distortion decreasing gradually as
the order increases. This is perhaps one of the problems with NFB. It cancels
the "benign" even harmonics, leaves exposed the more unpleasant odd
harmonics.

Utter bull****! NFB affects all frequencies equally - within the
limits of open-loop gain.

However my personal preference is for amplifiers that have minimal levels
of distortions at whever harmonics fall in band.

Cant argue with that! :-)

I have listen extensively to large Crown (Amcron) and Carver broadcast amps.
They have incrediblt low distortion figs which as a builder of valve amps I can
only dream of. They may be incredibly accurate, but their sound leaves me
cold.

So, you prefer the *added* artifacts of valve amps. Fine for you, but
what has this to do with fidelity to the source signal?

I agree entirely. It may also be that on the test bench
we put too much importance on some
measurements and do not undestand the relevance of others. In valve
amplifiers for example damping factor has an enormous bearing on the way
the amplifier sounds.

Only because it tends to be pathetically inadequate...............

One takes a high DF for granted in an SS amp. In
a valve amplifier, a figure above twenty (which seems adequate in listening
tests) is not easy to achieve.

So why bother with valve amps? Unless of course you have a
*preference* for added colouration................
--

Stewart Pinkerton | Music is Art - Audio is Engineering