Cable myths, or truths?

[Arturo Mieussens]

As far as I remember from my transmission lines class, for maximum power
transfer in a line the three impedances: output, line and input, have to be
the same, otherwise, reflections due to reactance (storal of electric
energy in circuit elements due to AC) occur and make part of the power 
travel back to the output stage. A "Directional" cable would have to be
made for connecting two speciffic devices only, and for a given lenght
only. it should also be constructed so that it haves a continuous change in
impedance, wich would be extremelly difficult to achieve.

Transmission line study is applied mostly for power lines, with great
distances and powers, and in wich a 0,000001% economy is a lot of money.
It's also usefull for high frecuency transmission lines (I mean Megahertz
or Gigahertz) at wich the reactive effects of the line are VERY big (think
about antennas, they are transmission lines).

For audio applications, with little power (yes, 1000 watts is little) and
very low frecuencies, it's more important to have good construction
quality, wich would reduce reactance, good noise rejection and basic
impedance matching than anything else, and yes, more power will make things
better.

And even if they where conducting DC a transmission line of any kind is
practically isotropic, that means, it's not "Directional" this includes any
metal such as copper, gold and silver (their molecular structure is really
all the opposite to directional, that's why metals can be bent without
breaking (plasticity) , so I also think this is B***S***.

Did you know that current is not the movement of all the electrons in a
conductor but a statistical average in the movement of the individual
electrons, wich occurs in ANY direction?, when potential (voltage) is
applied they are all "pushed a little bit more" to a side, but they are
allways moving randomly unless the temperature reaches absolute zero. So,
there's never a "Pure" DC (maybe in superconductors, but I haven't studied
that)

Buy good quality cable, with good noise rejection, low resistance and
overall good construction, there are many good brands (canare, for example)
and don't pay more than you have to.

I hope this helps.

Arturo.