ABSTRACT
The basic function of any crossover, be it passive or active, analogue or digital, is to take the audio spectrum that stretches roughly from 20 Hz to 20 kHz and split it into two, three, or more bands so they can be applied to loudspeaker drive units adapted for those frequencies. In hi-fi use the crossover frequencies are usually fixed and intended for work with one particular loudspeaker design, but for sound-reinforcement applications the crossover frequencies are normally variable by front panel controls. The need for any crossover at all is rooted in the impracticability of making a drive unit that can handle the whole ten-octave audio spectrum satisfactorily. There is of course much more to a crossover than simply splitting the audio signal into separate frequency bands. Crossover design is always a matter of compromise to some degree. Passive crossovers use only passive components, mostly capacitors and inductors. Active crossovers do have the important applications besides driving multi-way loudspeakers.
