Speaker wire is used to make the electrical connection between loudspeakers and audio amplifiers. Modern speaker wire consists of two or more electrical conductors individually insulated by plastic (such as PVC, PE or Teflon) or, less commonly, rubber. The two wires are electrically identical, but are marked to identify the correct audio signal polarity. Most commonly, speaker wire comes in the form of zip cord.

The effect of speaker wire upon the signal it carries has been a much-debated topic in the audiophile and high fidelity worlds. The accuracy of many advertising claims on these points has been disputed by expert engineers who emphasize that simple electrical resistance is by far the most important characteristic of speaker wire.

Resistance
Resistance is by far the most important specification of speaker wire. Low-resistance speaker wire allows more of the amplifier's power to energize the loudspeaker's voice coil. The performance of a conductor such as speaker wire is therefore optimised by limiting its length and maximising its cross-sectional area. Depending on the hearing ability of the listener, this resistance begins to have an audible effect when the resistance exceeds 5 percent of the speaker's impedance.

A speaker wire’s impedance takes into account the wire’s resistance, the wire’s path, and the dielectric properties of local insulators. The latter two factors also determine the wire's frequency response. The lower the impedance of the speaker, the greater a significance the speaker wire's resistance will have.

Where large buildings have long runs of wire to interconnect speakers and amplifiers, a constant voltage speaker system may be used to reduce losses in the wiring.

Wire gauge
Thicker wires reduce resistance. The resistance of 16-gauge or heavier speaker connection cable has no detectable effect in runs of 50 feet (15 meters) or less in standard domestic loudspeaker connections for a typical 8 ohm speaker. As speaker impedance drops, lower gauge (heavier) wire is needed to prevent degradation to damping factor – a measure of the amplifier's control over the position of the voice coil.

Wire size	2 Ω load	4 Ω load	6 Ω load	8 Ω load
22 AWG (0.326 mm2)	3 ft (0.9 m)	6 ft (1.8 m)	9 ft (2.7 m)	12 ft (3.6 m)
20 AWG (0.518 mm2)	5 ft (1.5 m)	10 ft (3 m)	15 ft (4.5 m)	20 ft (6 m)
18 AWG (0.823 mm2)	8 ft (2.4 m)	16 ft (4.9 m)	24 ft (7.3 m)	32 ft (9.7 m)
16 AWG (1.31 mm2)	12 ft (3.6 m)	24 ft (7.3 m)	36 ft (11 m)	48 ft (15 m)
14 AWG (2.08 mm2)	20 ft (6.1 m)	40 ft (12 m)	60 ft (18 m)*	80 ft (24 m)*
12 AWG (3.31 mm2)	30 ft (9.1 m)	60 ft (18 m)*	90 ft (27 m)*	120 ft (36 m)*
10 AWG (5.26 mm2)	50 ft (15 m)	100 ft (30 m)*	150 ft (46 m)*	200 ft (61 m)*

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