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From: prk@charm.UUCP (Paul Kolodner)
Newsgroups: net.audio
Subject: Hitachi super-pure cable
Message-ID: <659@charm.UUCP>
Date: Tue, 7-May-85 19:23:16 EDT
Article-I.D.: charm.659
Posted: Tue May  7 19:23:16 1985
Date-Received: Wed, 8-May-85 06:26:06 EDT
Organization: Physics Research @ AT&T Bell Labs Murray Hill NJ
Lines: 67

The recent posting about Hitachi super-pure cable really
gave me a laugh.  The author raves about how the number
of oxide inclusions has been miraculously reduced from 50,000
to only 19 per meter!  Then he/she says, roughly, that
it's gratifying that scientists can finally measure things
that humans can hear.  Well, a scientist who suspects that
this new cable is hot stuff for hearing as well as purity
would have done exactly what another netter suggested a
few days ago:  do a double-blind test with a lot of subjects
to see if humans can perceive the changes in the cable
associated by its breathtaking purity, rather than advertise
its electrical properties.  My guess, by the way,
is that they can't - more on that later.  The point of my
message, however, is this:  It's easy to make a lot of
fancy electrical measurements on inanimate objects like
cables and speakers.  It's a lot harder to objectively
quantify what meaning, if any, those measurements have, and
it's irresponsible to run around quoting numbers if they're
irrelevant or meaningless. A recent case in point in my 
life: I went to stereo store to by speakers and cables.
The salesman told me enthusiatically that I should use
gold-plated banana plugs rather than nickel because they
have lower electrical resistivity.  Think: what effect could the
difference in resistance between a micron of gold and a micron
of nickel have on a circuit with an impedance of many ohms?
Answer: zero. Period.  Salesmen are distinguished by their
willingness to uncritically and enthusiastically repeat
things they don't understand.  Here on the vaulted *NET*,
I hope we can do better.  Don't tell us the number of
inclusions per meter until you tell us how many inclusions
per meter we can HEAR.  Until then, it's less than useless
to know.

Now, let's talk a little about how many we CAN hear.  First of
all, a reply to the original posting asked about the analogy
of these little inclusions with a string of little capacitors.
If they act like a bunch of capacitors in series, the poster
asked, how come they don't seem like a huge impedance at 
finite frequencies?  Answer: because, whatever they are, they're
also in parallel with the rest of the (purer) copper, which has
low resistance.  The analogy was incomplete.
As for how many of the little buggers is too much, let me
just remind you that the metallurgy of copper is not a new field.
Even I know about it.  Every low-temperature physicist knows
that oxygen-free copper has much better transport properties at 
cryogenic temperatures than normal, impure copper, because,
at low temperatures, the phonons, which do all the scattering
at room temperature, are frozen out, leaving only the impurities
to muck up the electrical properties. If cupric oxide inclusions
were the dominant source of scattering of charge carriers at
room temperature, then I would concede that reducing their
density might have a strong effect on usefulness of speaker
cable.  But that's not the case.  Phonons dominate, accompanied
by scattering by the boundaries between microcrystals (grain
boundaries) and by other impurities.  50,000 clumps of CuO (size
1 micron, shall we say?) per meter of wire of diameter
of, say, 2mm,  works out to reasonably high purity, and there are
other things in there besides oxygen!  So my guess is:
you can't hear the oxygen in speaker wire unless your living room
floor is covered with liquid helium.  And, as I said above,
the rebuttal to my speculations is not to refer the Net to Hitachi's
memorandum no matter how reasonable it sounds, unless it documents
that their improvements in puroty can be heard.

DISCLAIMER:  Many of the replies I see in the Net are nasty and personal;
it seems that the authors use anonimity as an excuse for inhumanity.
My comments are not meant in this vain - otherwise they'd be in private.