Reference

Underpinning a discussion about the merits of potentially costly specialist audio cables is an obvious question: Why do we need them? Doesn't almost all wire conduct audio signals with negligible distortion and very little loss of power? Specialist hi-fi cables seem expensive for what you get. Especially at the upper end, they seem like a worse value than electronics and loudspeakers. Depreciation is greater, too: Cables are almost a consumable.

But if you wish to finesse the quality endeavor of classic separates-based hi-fi systems, you cannot do without them. Fundamentally, it is not the efficient transfer of audio power that's the issue; that is the easy bit. Rather, it is a matter of optimizing the transmission of the more subtle information that describes recorded acoustic, instrumental detail, the performers, and, not least, dynamics and rhythm: Are your feet tapping unconsciously in time to the performance?

The seemingly high cost of good cable is an inevitable consequence of often-arduous prototyping followed by a costly manufacturing run. Then consider stocking issues and the potential for product returns when the hoped-for improvement is not readily apparent when a cable is installed in a customer's system. What's more, a dealer needs excellent fieldcraft to reliably demonstrate the sometimes-elusive benefits that can come from cable substitutions. And then there's the markup.

How much of your budget should be allocated to a set of cables? Even the least expensive options will perform to some degree. With unlimited resources, you can spend whatever you like, even for small improvements, but 10%–20% of total system cost seems reasonable for a good audio system. Sometimes a given spend will have effectively topped out with just the speakers and electronics; subsequent system improvement can only be achieved by additional, perhaps stressful investments in those other bits, passive "components" such as cables and equipment supports, and—where aesthetically acceptable—room acoustic treatment.

Cables may sound mildly different from each other for a multitude of reasons (footnote 1). Mildly, because the gains to be won with cables are rather less than those experienced with most equipment substitutions. Some of these gains are significantly system dependent.

Take the usual passive loudspeaker–amplifier connection. At its simplest, it comprises a pair of insulated wires a few meters long of moderate—say, half an ohm—loop resistance, readily capable of carrying up to 25A or so of peak current. If our notional amplifier has an output resistance of 0.1 ohm, which is typical, the total resistance presented to the loudspeaker is then about 0.6 ohm. For a nominal 6 ohm speaker, the much-vaunted damping factor will be 6 divided by 0.6, or 10, which is unimpressive numerically. For many loudspeakers, both the Q factor (which controls damping) at low frequencies and the overall frequency response will begin to show increasingly audible changes at damping-factor values much lower than this. This is one way that small changes in sound quality may begin to intrude in a system unexpectedly.

Over-the-air audio signals, once limited to radio broadcast transmissions, now permeate modern domestic environments in the form of wide-bandwidth, high-frequency mobile phone, Wi-Fi, and Bluetooth signals. Hi-fi systems based on wireless connections have two significant implications with respect to cables, one positive, the other negative: On the plus side, they remove the need for interconnects and speaker cables and so one source of variability in system sound. On the minus side, they fill the space around our systems with a haze of high-frequency noise, which has the potential to influence how our systems (cabled or wireless) sound. Yet almost every system requires an AC power cord, which can affect the sound of a system in part by providing a route of entry for some of that noise into our systems via the AC line.

In classic, separates-based hi-fi systems, music information (in the form of electrical signals) travels along a selected cabled "track" from one component to the next—eg, from a phono cartridge to a step-up transformer to a phono preamp and on to a preamp and amplifier—or from a network player then to the preamp, etc., and then on to the speakers—all via suitably low-resistance cable. Each of those separates (except phono cartridges, step-up transformers, and passive preamplifiers) requires a power cable. These interconnects, speaker cables, and power cords all have the potential to moderately influence sound quality, individually and collectively. Moderately is a key word; such changes are small, yet we do get to choose if we want to, and with a following wind, perhaps make a difference that matters musically.

Notwithstanding market research, magazine reviews, dealer demos, and the advice of writers, dealers, and friends, we still must get those cables home and patiently try them out. Upon arrival, they are likely to need some mechanical relaxation and strain relief, gentle reflex bending in all directions following release from their packaging. Electrical running in and conditioning, too, often result in subtle improvements over time, maybe as much as months, with no guaranteed outcome.

Speaker cables may interact with the loudspeaker's load impedance, which typically is not constant over frequency. Such electrical matching effects may affect subtle shifts in timbre, bass weight and attack, and even midrange transparency. These may be rather more noticeable than anticipated from much vaunted superlow-loss insulators and superhigh-purity conductors. Such potential gains are frequently promoted to support heavy spending on hi-fi cables. At the same time, such technology improvements may well be audible in the sound-quality mix, usually as subtle nuances. It is all a matter of proportion.

Damping factor, which has already been discussed to some degree, is a measure of the connected system's ability to control power coming back from the operating loudspeaker. This may include electrically reactive components, ie, with phase shifts such as those generated in the crossover network and further compounded by reverse/reactive current from dynamic moving parts including driver voice coils. Keeping loudspeaker cable resistance low helps ensure more consistent performance overall, preserving the effective damping factor, especially for "dynamic," moving coil loudspeakers.

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Footnote 1: Stereophile published a theoretical examination by Malcolm Omar Hawksford on how and why audio cables might affect sound quality in October 1995. Also see this 1998 article on experimental evidence by Ben Duncan.—John Atkinson