The Parallel-Fed Crossover

Author: N.H. Crowhurst

To obtain power division, both inductance and capacitance must be used, for even the simplest network. Here the dividing elements do not absorb any power and all the power goes to the loudspeakers. If a capacitor is connected in series with a speaker, it will block the lower frequencies and allow only the high frequencies to get through to the speaker. The loudspeaker with an inductor in series with it will receive only the lower frequencies, because the inductor will block the higher ones.

A simple crossover

If the right values of inductance and capacitance are used, both loudspeakers will get half the power at a middle frequency, called the crossover point. At frequencies below this, more of the power goes to the speaker with the series inductance, whereas above the crossover point, progressively more of the power goes to the speaker with the series capacitor. The current between the two loudspeakers is divided in this way. Because each branch of the circuit delivers its current to a load resistance (one loudspeaker), the current is accompanied by a proportionate voltage, and a power division results. We can also use these components to effect a power division by dividing the voltage.

Frequency response of a simple crossover