In article , Andy Evans
wrote:
I enclose the following, from Geoff Mead (Audiocircle): does anybody
know anything about this? Quote goes:

Re the current thread on speaker cables and sonic differences between
different amp/cable/speaker combinations. There has been an interesting
series of articles in Electronics World staritng June 2004 if anyone
hasnt seen them.

It is my misfortunte that I have been reading this series of articles. I'm
afraid that to me they seem like a catalog of confusion, incorrect
information, and statements made well out of context so as to give a wholly
misleading impression. Thus some of the individual statements made in the
articles are correct, but used in inappropriate ways. I would strongly
recommend anyone reading the articles to treat what they say with great
caution and look with care for the 'errors and omissions'.

Hesitate to say this as my own writings can sometimes be unclear, but the
articles also suffer in places from a style which seems rambling and
ambiguous. Some of the 'sentences' are rather long-winded and - to me -
make it harder to work out what he really means.


The author Graham Maynard started looking at the old
chestnut as to why valve amps sound different from S/S ones particularly
when played loud. To cut a long story short he proposes that Miller
compensation and series output inductors are responsible in causing what
he calls First Cycle Distortion.

Yes. That is one of the muddles he gets into. :-)

He also dislikes input filters, based upon a similar muddle. :-)

His proposition is that the reactive impedance characteristics of most
loudspeakers interact with s/s amps that have these features over the
first cycle of each frequency component that makes up the music
waveform.

However if you examine his examples and aguments with care you will find
them misleading and often out of context so as to 'exaggerate' or imply
significance that may be absent in reality.

He suggests that these effects disappear after the first few
cycles and therefore do not show up in pure sine wave testing. An
interesting conjecture, yet to be fully proven,

Afraid the problem here is not 'proof' but of the author actually
understanding and explaining clearly. :-)


but the point is that the reactive elements of connecting cables would
also figure in this argument.

Yes, they could. Thus if he worries about the output inductor he also
should worry about cable inductance. And, of course, the effective output
impedance of valve amps... :-)

If this were true then valve amps should be much less affected ( SE
types excepted?)

They would only be 'less affected' by virtue of the following two possible
factors:

A) The valve amp having less output at the high frequencies implicit (but
hidden) in his argument due to the amp having a limited HF output reaching
into the audible range.

B) The valve amp having such a high across-the-band output impedance as to
swamp the cable inductance. However this simply means you are producing a
larger problem in order to make a small one matter less.

TBH I have been wondering about producing a detaild 'critique' of the
Maynard series as they are riddled with some many misleading statements and
evidence present out-of-context. However I have so far been dissuaded as
the series hasn't finished, and I also have an article (on a quite
different topic) to be published in a later EW. :-) Been hoping that
someone else would be willing to spend the time pointing out the problems
with his articles. ;-

I would recommend the articles to any engineer or academic who wants to
have material for a 'forensic analysis' of the mistakes people can make
when trying to understand or explain a technical topic. Indeed, such an
analysis might make a neat MSc dissertation for someone. The articles are
well filled with bones which can be picked out. :-)

More seriously, I must admit I sighed when I first saw these articles. I
had hoped people would no longer be getting confused like this. Must admit
I am wondering if the editor of EW is running it deliberately to stoke up
loads of 'letters to the editor', etc. ;-

Slainte,

Jim

--
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