For best design results, the
crossover should "see" the same resistance from the woofer through out the
frequency range. However, the voice coil resistance changes as frequency increases.
The woofer's impedance curve can be flattened by placing a resistor and capacitor between
the woofer and crossover network. The DC resistance ( R e ) and inductance ( L
) parameters of the driver are
needed to determine the component's values.