Choosing Loudspeaker Cable for the Audiophile

Loudspeaker cable is the least glamorous purchase in a system, and the most argued about. It is worth separating the properties that measurably affect the sound from the claims that are hard to pin down.

Resistance comes first. The cable sits in series between amplifier and loudspeaker, so its resistance wastes a little power and, more importantly, interacts with the loudspeaker’s impedance curve. Where the impedance dips, the cable’s resistance takes a larger share, and the frequency response shifts slightly. A common rule of thumb keeps the total resistance of both conductors to a small fraction of the loudspeaker’s minimum impedance, often quoted as no more than about five per cent. That means a heavier gauge for longer runs and for low-impedance loudspeakers.

Keep runs as short as the room allows, and make both channels the same length, even if one side needs a loop of spare cable. Unequal lengths are a small effect, but an easy one to avoid.

Inductance depends on the cable’s geometry. Conductors spaced well apart have more inductance, which can soften the top octave slightly on long runs. Closely spaced, twisted or woven conductors have less. Capacitance rises as conductors move closer together, and most amplifiers are indifferent to it. A few designs, however, can become unstable into very high-capacitance cables. If you are considering an unusual low-inductance cable, check with the amplifier’s maker first.

Tube amplifiers add one consideration. Their output impedance is already higher than that of most solid-state designs, so cable resistance is a smaller part of the total, but there is no reason to add more than necessary. Use the output tap that matches your loudspeaker’s nominal impedance.

Terminations matter more than they look. A loose or oxidised connection adds resistance and can make contact intermittent. Use well-made spades or plugs, or clean, freshly cut bare wire, tighten binding posts firmly by hand, and check them now and then. If your loudspeakers have two pairs of terminals, bi-wiring is an option; if you do not bi-wire, use good-quality jumpers rather than thin metal straps.

Beyond these basics, judge claims about direction, exotic materials and special treatments by listening in your own system, ideally with a return option. Buy enough good wire, route it carefully away from mains cables, and spend the difference where it can be heard.