Crossover Networks

Inside the speaker cabinet is an additional component called the "crossover network". This is made of one or more resistors, capacitors, and inductors (see schematic diagram of a typical circuit on the right). The property of a capacitor is to pass high frequencies, but to impede low frequencies, while inductors pass low frequencies and impede high frequencies. Resistors are used to balance the loudness between the various drivers. The components are wired so that only high frequencies are sent to the tweeter, midrange frequencies sent to the midrange driver, and low frequencies to the woofer (in the case of a three way design). The crossover network, named for the fact that it crosses over frequencies to the proper driver, has connections to the binding posts on the rear of the speaker, so that the signal passes through the crossover network, and then to the speaker drivers. The property of sending low frequencies to the woofer is called "low pass", and the property of sending high frequencies to the tweeter is called "high pass". You may see these terms used, for example, in setting the low pass frequency that a subwoofer crosses over at, sending all signals below this frequency to the subwoofer amplifier, and the high pass frequency, above which, signals are sent back to the main speakers.2003-07-crossover-networks-primer-diy7schematic.gif