high end audio

Importance Of Overall Speaker Cable Geometry
We have been discussing problems within a single conductor, solid or stranded, regardless of polarity
(+ or -). The relationship between conductors is also very important. If this relationship is not consistent,
then the electrical parameters (such as capacitance and inductance) of the cable will be constantly
changing and the signal will be distorted. Conductors can be parallel, spiraled (twisted), or braided.
These various geometries have certain inherent qualities. Parallel construction is inexpensive. Spirals
have good RFI (radio frequency interference) rejection and usually lower inductance. Braids have good
RFI rejection and low inductance, but suffer the consequences of a constantly changing electrical environment
for each conductor.
A cable may have two or more conductors. The arrangement of these conductors dictates the magnetic
interaction, the capacitance and the inductance of the cable. Both capacitance and inductance cause
predictable and measurable filtering and progressively more phase shift at higher frequencies, though
neither is a magic key leading to optimum performance. The effect of capacitance is somewhat like a
cliff, you can go near the edge as long as you don’t go over the edge. In a given application there is a
value at which capacitance becomes a problem. At a lower value, away from the edge of the cliff, there
is not much penalty. On the other hand, inductance is always a problem-a constantly accumulating
problem. Capacitance and inductance are not the only important variables in cable design. However,
it is productive to create cables whose capacitance doesn’t "go over the cliff" while also designing for
minimum inductance.
One theory of cable design holds that the characteristic impedance of a cable should match the impedance
of the loudspeaker (When an antenna cable is referred to as 75 or 300, that is the characteristic
impedance). Impedance matching is a valid concept which only applies when the impedance of the
source, the cable and the load are all the same, and when the cable is longer than the wavelengths
of the frequencies to be transmitted. Amplifiers do not have 4 or 8 ohm output impedances, in fact
amplifier designers try to have as low an output impedance as possible. Speakers are all different and
never have the same impedance at all audio frequencies. Since characteristic impedance equals the
square root of the ratio of inductance to capacitance, very high (over the cliff) capacitance is a necessary
corollary of a low characteristic impedance. Such high capacitance can severely affect amplifier
performance and should be avoided.
Some of the first generation of specialty speaker cables had a characteristic impedance of about 8.
These very high capacitance cables sounded better or worse because of their ability or inability to deal
with the problems discussed earlier. However, many of these cables were accused of being extremely
bright and irritating. It was not the cables which were so bright, it was the sound of the amplifier,which
had been encouraged into instability by the cables.
Such false conclusions could be avoided if products were judged on their merit and then methodically
analyzed. Consumers, store buyers, and reviewers each need to discover what sounds good. Unfortunately
the desire to understand "why" can cause more confusion than insight if not pursued empirically
as well as theoretically.