The Crossover Frequency is the exact point at which a speaker's crossover "passes the baton" from one frequency to another between the speakers.

It is the frequency at which sound stops being reproduced by one speaker (such as the woofer) and starts being reproduced by another (such as the tweeter).

At this frequency, both speakers (woofer and tweeter) are working together, but one is decreasing its volume while the other is increasing it.

In a two-way speaker system, the crossover frequency is usually between 1 kHz and 3 kHz. The manufacturer's choice of frequency is one of the most important factors for the tonal balance and sound quality of the speaker.