Speaker wiring carries the amplified audio signal from the amplifier’s output terminals to the speaker drivers. While it may seem straightforward, the details of speaker wiring — gauge, polarity, routing, and connection quality — have a meaningful impact on sound quality, system stability, and longevity.
Wire gauge for speaker runs is generally less critical than for power wiring, since the current levels are lower and the distances shorter. That said, using adequately sized wire (typically 16 AWG for most applications, 14 AWG for longer runs or higher-power applications) ensures that resistive losses in the wire do not measurably reduce the power reaching the speaker or alter the damping factor of the amplifier-speaker interaction.
Polarity is critical. Each amplifier channel has a positive (+) and negative (−) output terminal, and each speaker has a corresponding positive and negative terminal. These must be matched consistently across all speakers in the system. Reversed polarity on one speaker in a pair causes them to work against each other, producing a thin, hollow sound with a noticeably diminished low-frequency response. The convention is to use the positive terminal for the positive wire throughout — typically identified by a red wire, a stripe, or a ribbed texture on one conductor of the pair.
Speaker wires should be routed away from power cables to avoid induced noise. In door installations, a service loop of extra wire should be left at the door hinge area to accommodate the door’s range of motion without placing tension on the conductors over years of use.
Termination at the speaker end can be done with spade connectors, bare wire wrapped around binding posts, or push-in terminals depending on the speaker design. Whatever the termination method, the connection must be mechanically secure and corrosion-resistant, as vibration and moisture in the vehicle environment will exploit any weakness over time.