The Physics of Electricity

“When a cable carries a pure tone, perhaps a sine or square wave, then frequency and time are interchangeable, meaning that the only distortion of the signal would be attenuation. But music is far from a pure tone, and is a complex flood of frequencies in the 20 Hz-20 kHz range. When you send multiple frequencies down a cable, you introduce the possibility of time-based distortion, as different frequencies are affected differently by reactive variables such capacitance and inductance. Our ears are quick to hear the deterioration in fidelity based on frequency-arrival time and phase coherence.

To compound the issues, audio frequencies lie in an awkward electromagnetic region for conductors. Don’t forget that audio frequencies are at the bottom end of the spectrum; these are among the slowest, longest wavelengths of electromagnetic energy we harness.

Electromagnetic wave propagation: what exactly is the “signal”?

To understand why cable design has an effect on a signal in the first place, it’s important to understand exactly what this “signal” is, and how it “travels” along the cable.

Visualize the wire as a tube that’s the diameter of a set of marbles which you can push down the tube; the marbles are the electrons. Electrons don’t move without also causing electromagnetic fields, so now imagine a donut with its hole centered around this marble tube. This is the magnetic wave (B field). Now, take a bunch of toothpicks and stick them around the outside of the donut—this is the electric field (E field) produced by the moving electrons.”