Speaker wire

RCA speaker wire

Speaker wire is used to make the electrical connection between loudspeakers and audio amplifiers. Modern speaker wire consists of two electrical conductors individually insulated by plastic. Both a positive and a negative conductor are provided. Certain older designs also featured another pair of wires for a powered line to power an electromagnet in the loudspeaker before permanent magnets became economical to produce and use.

The effect of speaker wire upon the signal it carries is a much debated topic in the audiophile and high fidelity worlds and equally debated is the honesty of its marketing.

Explanation

A speaker wire acts like any other electrical connection and has three parameters that determine its performance: resistance, capacitance, and inductance. A perfect wire would have no resistance, no capacitance, and no inductance. The shorter a wire is, the closer it comes to being perfect. These three measurements are independent of the frequency of a signal being passed through the wire.

The quality of construction is often just for aesthetic purposes and convenience. Highly stranded wires tend to be more flexible and hence easier to work with. For a wire that will be exposed, often in a home, (rather than run in-wall or otherwise hidden), looking more appealing may be a benefit but is wholly subjective. Better purification of oxidizing materials such as copper will result in more consistent conductive properties throughout the life of the wire. Better jacketing may be thicker or tougher (to prevent breakage), less likely to tangle and easier to pull through a group of other wires, or incorporate a number of shielding techniques.

Even with a poor wire, an audible effect may not exist. Many supposedly audible differences in speaker wire can be attributed to the result of listener bias. Listener bias is helped in no small part by the large number of wire manufacturers making unscientific claims about their own product. Many manufacturers catering to audiophiles as well as those available in department stores make unmeasurable claims about wire being open, dynamic, or smooth. To justify the claims, many rely on less understood electrical properties such as skin effect, characteristic impedance of the cable or resonance (these have no measurable effect at audio frequencies but are important at radio frequencies) [1].

Resistance

The lower the impedance of the speaker, the greater the significance of the resistance of the speaker wire will be. Few speakers have the same impedance throughout the frequency spectrum; the rated impedance is generally either the maximum or the average impedance, depending upon the source. In speakers with variable impedance, the resistance of the wire will have the most effect at the frequencies where the speaker is a lower impedance, potentially leading to audible variation in the output if the impedence of the wire is high enough. Assuming a constant speaker impedance, a higher wire impedence will only lead to a loss in power.

To achieve a low resistance in the wire, use shorter lengths, a larger wire, better conducting materials. To keep mutual inductance to a minimum, keep the speaker wires away from heavy current circuits, and avoid random touching of grounded surfaces.

Wire gauge

A larger gauge of wire is achieved by increasing its size or diameter. The American wire gauge (AWG) system uses lower size numbers to represent a larger gauge. Sizing in millimeters is also common.

Wire material

The generally advised material for speaker wire is copper, which has low resistance and cost, which has made it the dominant conductor material. Copper and aluminum oxidize; however the oxides of copper are conductive, those of aluminum are insulating.

Silver has a slightly lower resistivity than copper, which allows a wire with a lower gauge but equal length to have a lower resistance. However, due to silver cost, a higher gauge copper wire is more economical and can result in the same resistance or lower much more cheaply. Like copper, silver also suffers from oxidation.

Gold has a higher resistivity than either copper or silver, about twice that of copper. Gold does not oxidize, so it is often used for wire end terminations through the use of gold-plated connectors, to achieve the best of all worlds.

Terminations

Speaker wire terminations are optional and largely for convenience, bare wire works just as well or better electrically. The most common termination types are soldered wire ends, soldered or crimped pin or spade lugs, and banana plugs. Which type to use is determined by the receptacle the speaker wire is being plugged into. Many terminations are plated in gold to prevent any change in conductivity.

Many speakers and electronics feature five way binding posts that can be screwed down or held down by a spring to accept bare or soldered wire and pins or springy "banana" plugs (through a hole in the outward facing side of the post. The use of the larger 12awg may necessitate cutting away 30% of the bare strands in the 0.375" length for a termination; but, such does not measureably change the electrical characteristics of the wire.

Proprietary connectors also exist, though largely on all-in-one entertainment centers and bookshelf stereo systems.

In recent years, the Neutrik Speakon connector is appearing more and more on European audio equipment. The reason for such is simple: in many European Countries, especially Germany, the banana plug is coincidentally the same size as the live pins of an electrical outlet, delivering a lethal 230 volts to the user and to the speaker or other attached equipment. Recent EU regulations prohibit banana plugs, unless they have a safety pin mechanism preventing insertion into a wall outlet. WBT Connectors makes a model of such a plug that is commercially available.

Speaker wire manufacturers