A loudspeaker crossover is a circuit that divides an audio signal into different frequency ranges before sending those frequencies to the appropriate drivers within a loudspeaker. It allows each driver to reproduce the frequencies it has been designed to handle.

In a typical two-way loudspeaker, the crossover sends lower frequencies to the woofer and higher frequencies to the tweeter. In a three-way loudspeaker, the signal is usually divided between a woofer for bass frequencies, a midrange driver for the middle frequencies and a tweeter for high frequencies.

The point at which frequencies are divided between drivers is known as the crossover frequency. Rather than abruptly stopping one driver and starting another, a crossover normally reduces the output of each driver gradually around this frequency. This allows the drivers to work together and produce a smoother transition between different parts of the frequency range.

Passive loudspeakers generally use passive crossovers located inside the speaker cabinet. These circuits typically contain components such as capacitors, inductors and resistors and operate on the amplified signal received from the amplifier.

Active loudspeakers can use active or digital crossovers that divide the audio signal before it reaches the individual power amplifiers. Each driver can then have its own amplifier channel, giving the manufacturer greater control over how the drivers operate together.

A crossover does more than simply divide frequencies. Its design can also help balance the output levels of different drivers and influence their phase and overall integration. The crossover therefore plays an important role in determining how smoothly and accurately a loudspeaker reproduces music.

The quality of a loudspeaker depends on how successfully its drivers, cabinet and crossover work together. A carefully designed crossover helps create a consistent sound across the frequency range, allowing multiple drivers to behave more like a single coherent loudspeaker.