aq_cable_theory 9 | Biblioteca audio audioquest

as well as theoretically.

In low-current cables; skin-effect, electrical interaction, magnetic in-

minimum inductance.

The Challenge Of Interconnect (Low-Current) Cable Design

cables, then please read that first. The following is meant to build

If you haven't read the previous discussion of problems in speaker

problem. Capacitance and inductance are not the only important variables in cable design. However,

Page

bright and irritating. It was not the cables which were so bright, it was the sound of the amplifier,which

in which a particular material absorbs and releases energy), has a

fields is greatly reduced.

The problem is that any insulating material next to a conductor acts like a capacitor which stores and

never have the same impedance at all audio frequencies. Since characteristic impedance equals the

performance and should be avoided.

hierarchy among these problems differs.

of the frequencies to be transmitted. Amplifiers do not have 4 or 8 ohm output impedances, in fact

teraction and conductor quality are still primary problems. The nega-

nately the desire to understand "why" can cause more confusion than insight if not pursued empirically

analyzed. Consumers, store buyers, and reviewers each need to discover what sounds good. Unfortu-

more important in low level cables. Dielectric involvement (the way

amplifier designers try to have as low an output impedance as possible. Speakers are all different and

sary corollary of a low characteristic impedance. Such high capacitance can severely affect amplifier

tive sonic effect of internal mechanical modulation due to magnetic

CABLE THEORY

on that foundation. The same problems exist in both high-current

propagation are even more useful.

(speaker) and low-current (interconnect) applications. However, the

source, the cable and the load are all the same, and when the cable is longer than the wavelengths

One theory of cable design holds that the characteristic impedance of a cable should match the imped-

Some of the first generation of specialty speaker cables had a characteristic impedance of about 8.

is not much penalty. On the other hand, inductance is always a problem-a constantly accumulating

with the problems discussed earlier. However, many of these cables were accused of being extremely

had been encouraged into instability by the cables.

The electrical behavior of the dielectric (insulating material) is much

ance of the loudspeaker (When an antenna cable is referred to as 75 or 300, that is the characteristic

profound effect on an audio or video signal. Dielectric constant, the most often quoted specification for

square root of the ratio of inductance to capacitance, very high (over the cliff) capacitance is a neces-

Such false conclusions could be avoided if products were judged on their merit and then methodically

impedance). Impedance matching is a valid concept which only applies when the impedance of the

insulating material, is actually not very helpful in understanding the audible attributes of different materi-

These very high capacitance cables sounded better or worse because of their ability or inability to deal

it is productive to create cables whose capacitance doesn't "go over the cliff" while also designing for

als. The coefficient of absorption value is more relevant, and the dissipation factor and the velocity of