A crossover network divides an audio signal into multiple frequency bands. This is done to optimize which frequencies are directed to multiple speaker drivers, for example, a woofer for low frequencies and a tweeter for high frequencies.( It is difficult for one driver to accurately reproduce sound waves over the entire 20 Hz to 20 kHz frequency range of human hearing. Splitting the frequency range up into multiple bands with a crossover, each dedicated to their own driver, allows the speaker to more efficiently reproduce full-range audio with better fidelity. This requires a crossover network to divide the electrical audio into a high-frequency part and a low-frequency part before the signals reach the drivers.
The frequency where the sound is divided is called the “crossover frequency.” Ideally, when crossover network is used in a speaker enclosure, a crossover frequency is chosen that protects the tweeter, allowing it to produce only those frequencies that it can reproduce the best, and allows both the response and coverage pattern of the woofer to blend well with the tweeter.