Hooking up a crossover in a PA system requires all components to be separate. Many small systems use integrated mixer/amps, and have "passive" electronic crossovers built into full-range speakers. In a component system, crossovers are "active" rack mounted components, used to split sound frequencies for efficient and adjustable distribution to separate amplifiers and speakers. The use of dedicated amps and speakers for each frequency is called "bi-amping" or "tri-amping," for two or three-way systems respectively. In a simple bi-amped system run in mono, a single stereo power amp can be used by assigning one channel for low frequencies, and the other for high frequencies.
Plug one end of a shielded input cable into the mixer's main output, and the other end into the crossover's input. The cable connectors will be dictated by your particular mixer and crossover, and will be either standard 1/4" or 3-pin XLR connectors. Consult the owner's manual of all components for specific details and recommendations.
Plug another shielded input cable into the crossover "high" frequency output, and the other into the crossover's "low" frequency output.
Plug the cable coming from the crossover "high" output into the channel one input on the stereo power amp, and the cable from the crossover "low" output into the channel two input of the power amplifier.
Plug one end of the unshielded speaker cable into the power amp channel one speaker output, and the other end into the horn tweeter.
Plug one end of the second unshielded speaker cable into the power amp channel two speaker output, and the other end into the woofer. The connections are now complete.
Follow all owner's manual recommended frequency settings for the crossover, and consult the speaker and horn manufacturer specifications sheet for frequency handling.
If a component equalizer will be used, it is connected between the mixer and crossover.
Always remember "input to output" when connecting any component.
Three, four, and five-way systems may be achieved by adding additional speakers and power amp channels to crossovers designed for these systems. They are hooked up in the same fashion, there are just more wires, amps, and speakers.
Not following speaker frequencies set by the manufacturer can cause serious speaker damage.
Label or color-code all cables to assist in future set-ups, and to prevent potential system damage from cable mix-ups. Plugging low frequencies into the horns will blow the horn drivers.
Make certain that the speakers can handle the amplifier power, especially the horn tweeter driver. Horn drivers don't require as much power as woofers, and can blow easily. If your amplifier is too powerful, you will need to add a separate amp of lower power to drive the horns.