Passive crossovers are used in 2-way and 3-way speaker systems to electrically channel low tones to the bass loudspeaker, and high notes and overtones to the high frequency speakers. If a passive crossover has to fulfill its function without compromise, it must be able to handle extreme variations in dynamics, the full range of audio frequencies, complex transients, and the varying impedance of a loudspeaker load. ESB passive crossovers are carefully designed to complement the exact characteristics of ESB speakers. Each crossover network circuit controls the signal to the high and low frequency speakers so that smooth acoustic response is maintained through the full audio spectrum. Naturally, such sophisticated engineering demands very close tolerances in production. Ordinary crossovers, for example, often use electrolytic capacitors with tolerances of +/- 20% and metal core inductors. Response through these crossover regions is ragged and characteristics vary from unit to unit. All ESB networks, on the other hand, use only non-inductive polypropylene or mylar dielectric capacitors (not electrolytic units) individually tested to meet ESB’s stringent tolerances. The special inductors used in ESB networks have extremely low insertion loss so that none of the driving power to the speaker system is wasted in the network. To avoid interference between the inductors, they have been installed with a rotation of 90°. This arrangement cancels the interactions. All the resistors used to align the level of the various speakers with each other are of the non-inductive type and their power is greatly over-sized. A switch located on the output side allows the user to adjust the tweeter level on two options according to the distance of the tweeter from the listener (and for the midrange in the 5.6K3 CX). Both the input and output connections are robust, two-way audio connectors with locking screws. They accept cables with gauges up to 4.5 mm (6 AWG). Even the PCB was not left to chance. The thick copper traces limit signal loss.