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- Oxygen Free Cables
Re: Oxygen Free Cables
** You incredibly illiterate moron!!!!!!!!!???????!!!!!!
He asked "Anyone got an equivalent circuit to model the impedance of an
ESL?" You answered - "No, but I've got two cream cakes for little-lunch".
** Learn to read English. Then comes comprehension lessons. Don't even
think about trying to reply coherently until you pass.
Re: Oxygen Free Cables
You are right to be sceptical about "oxygen-free" -and indeed that most
claims about purity of the conductor make any difference to the sound. The
usually quoted explanations for effect of purity are changes in resistance
and diode effects.
You have to add a lot (certainly more than the ppm cable manufacturers
rabbit on about) of impurity or other crystal defects to affect the
resistance - it was a technique used in the Dept of Tribophysics of CSIRO
based in Unimelb in the 1950s to study metals (before my boss in
Cambridge/Oxford developed electron-microscopy techniques for more direct
examination of such defects in metals). Put simply, the conduction
electrons are effectively detached from their atoms in metals (hence they
are called 'free electrons') and there are so many of them (of the order of
10**22 per cm**2) that they only have to travel very slowly (mm/sec) to
conduct even the largest of the currents likely to occur in audio ( less
than 100 A). You have to put a lot of barriers in their way for them to
notice any difference in resistance - and this can always be compensated for
by making the conductor slightly thicker.
Likewise you have to work pretty hard to dissolve enough oxygen to form
copper oxide precipitates inside copper . Oxides are semiconductors (i.e.
they have fewer free electrons) but this does not automatically create
'diodes' - and any such effect would in any case be short-circuited by the
metal around them.
On the other hand, the dielectric around the conductors will affect the
propagation of the electromagnetic fields which drive the electron currents
inside the metal, for reason explained in earlier posts - see
This article also explains why thickness of the conductors may be important
through 'skin effects' - AC currents become increasingly concentrated on the
surface as frequency increases, even at audio frequencies. Likewise the
geometry of the strands will affect the AC capacitance & inductance of the
cable (and as Hawksford explains, you generally have to trade one off
against the other).
I have certainly heard differences between cables but it tends to only
become important in high resolution hifi systems.
Dr Rod Crawford
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