Why does the gauge of speaker wire matter? Options

[mkop]

I've read some things discussing speaker wiring such as speaker reviews and their is always something like "the included cables are ok but you'll probably want to go and get something thicker." My question is why do I want some huge python of a cable? And what principles are used to decide what size is big enough?

[JeanLuc]

There are three major parameters that influence electric conductivity (and thus the sound) of a given speaker cable.

1.
The specific ohm resistance (resistivity with the greek designation Rho, SI Unit is Ohm·mm2/m is a material constant which will be multiplied with length and divided by diameter and result in an non-frequency-dependent Ohm Value.

At 20°C, the Rho value for copper is: 0,0178 Ohm·mm²/m

This pure ohm resistance will neither cause phase shift of the electrical signal nor will it cause a loss in a relevant frequency band. If this resistance becomes bigger, you just lose volume (just like a potentiometer). Only in case of very high currents (some speakers' impedance undershoots 1 Ohm in the low end which will demand high currents from your amplifier), the cable will heat up and thus change its specific resistance and sound. This can happen, but most likely it won't.

2.

A cable always states a capacitance (C, measured in the SI unit Farad) which states a complex (frequency-dependent) Resistance RC (RC hyperbolically follows C/f which means that in the low-end, RC gets higher) ... your target should be to avoid a cable with a high capacity (funny thing is that thicker cables show even higher capacities).

Capacitance causes a positive phase-shift BTW.

3.

Inductivity (I, measured in Henry) is the third major resistance which mostly occurs when winding up cable to some sort of coil ... this resistance is complex as well and affects the high frequencies (RI follows I·f) - a cable with higher inductivity might dampen high frequencies.

Inductivity causes phase shift as well, in a reversed direction to capacitance.

If you take a look at a frequency crossover network, you will find resistors, capacitors and coils put together to split up frequency bands according to the used chassis in the loudspeaker.

As you can see, your cable doesn't need to be thick as long as you do not cover long distances or loading the cable with extreme currents - thick cable will show higher capacitance which might influence bass response in a negative way.

Marketing allows a lot of so-called "wonder cables" to be established in the high-end (or high-price) segment - but I think that no one will be able to reliably ABX some high-end Monster cable against standard copper cable of the same diameter (changes in simple loudness due to variation of diameter might be detectable, though).

What you might be able to ABX against speaker cable is perhaps some thin wire, used for door bells or telephones ....