Uses electronics supplied with a power source and acting on the sound to shift sound reproduction tasks from one speaker driver to another. A crossover is necessary in a speaker because one driver cannot efficiently handle all sound reproduction tasks across the entire audible spectrum (the sounds distinguishable by the human ear – from around 20 Hz to 20 kHz).

The crossover splits up the frequency spectrum into pieces that are then handed over to various speaker drivers. A two-way crossover, for instance, may split the frequency spectrum into a frequency band from 20 Hz to 2 kHz and from 2kHz to 20 kHz. The woofer section of the speaker would then reproduce the section from 20 Hz to 2 kHz while the tweeter would take over above 2 kHz. This scenario works essentially the same for all crossovers (active and passive), however, an active crossover accomplishes this through adjustable electronic components.

Active crossovers are the most flexible types and they also are the highest quality (sound quality). Compared to passive crossovers, which are fixed and use specified filters and capacitors, active crossovers are adjustable and use electronic circuits to split up the frequency spectrum. These electronic circuits are often “cleaner” sounding than their passive counterparts. Active crossovers can be purchased as separate components to be used in an audio system. They are also used in many preamplifiers and receivers to set a crossover point for a subwoofer. In addition, most if not all powered subwoofers include active crossovers to split up the signal which they will reproduce from that which should be passed on to the other speakers. In contrast, passive crossovers are mainly found hard-wired into speakers themselves where they split up the signal between the driver elements in the speaker enclosure.