The Gauge of Wire From a Crossover to a Speakerby David Lipscomb
The multiple individual transducers comprising a speaker system are called drivers. Each driver reproduces a section of the audible frequency range, but the full-range signal from the amplifier to the speaker must first be divided for accurate sound and to prevent driver damage. Crossovers are active or passive electronic networks, separating the signal into high, mid and low frequencies. Wiring from the terminal plate to the crossover and on to the individual drivers requires wiring, necessary in transferring the electrical information through the signal chain.
Gauge and Distance
Speaker wiring is chosen based on the distance it travels from the power source or amplifier to the speaker. The length of wire to the speaker terminals from the amplifier determines the gauge that may be used; longer distances require thinner wire. Up to 50 feet, 16 gauge wire is acceptable and necessary to prevent excess resistance in the wire. This creates a thin sound, lacking in impact. Beyond 50 feet, 14 or 12 gauge wire is required. However, inside the speaker from the terminals to the crossover and from the crossover to the drivers only requires 18 gauge, since the distances inside the cabinet are normally only a few inches. Larger gauges may be chosen for various design reasons separate from electrical necessity. However, thicker wire may make soldering and fitting drivers more difficult than necessary.
Car audio applications often present variables installation variables normally not present in a conventional home audio environment. Car audio crossovers are often designed with attractive cosmetics, under the assumption that they will be showcased with amplifiers, equalizers and other devices. In these cases, placing the crossover immediately by the speaker drivers they feed may not be practical nor desirable. Running the gauge needed to properly address the distance from the amplifier to the speakers is necessary. Remember that passive crossovers are parasitic, meaning that they absorb a certain percentage of amplifier power prior to the signal reaching the speaker. At minimum, it's wise to use 14 gauge speaker wire in mobile environments to counter these installation issues, as well as properly addressing the high-wattage amplifiers often used in car audio applications.
The primary difference between crossovers revolves around passive and active devices. Passive crossovers are those consisting of a board filled with resistors, chokes and capacitors. These units are most commonly found inside speaker cabinets and packaged with speaker systems designed as components for car audio. These require speaker wire. Active crossovers are powered devices, placed between a preamplifier and amplifier. Active crossovers use RCA signal cables and adjustable crossover points to divide the signal. Because amplifiers do not directly feed active crossovers, speaker wire gauge is not a factor. However, using excessively long RCA cables from the preamplifier to the crossover and on to the amplifier or amplifiers may result in a reduction in signal quality, due to increased capacitance.
Speaker Wire Terminations
Connections between amplifier, crossover and speakers vary depending on the specific configuration. Conventional connections inside a speaker cabinet usually involve crimped ring terminals connecting the two lead wires from the inside of the terminal cup to the crossover, which uses a soldered joint. The crossover outputs are also usually soldered, leading to crimped slip-on spade terminals to the back of each driver. Car audio systems usually involve crimped spade lugs under a screw-down compression plate to and from the crossover. Like home audio speakers, slip-on terminals are used at the back of each driver. Some premium drivers including subwoofers use spring-loaded binding posts, securing bare wire leads to the back of the speaker.