Audio Engineering

Loudspeaker Enclosures 729

In the crossover’s pass band where there should be no (attenuative) action on the signal
voltage at all, the crossover should be “ transparent. ” In practice, one pass band is another
driver’s stop band. Even a steady-state test signal will experience the added reactive
loading at most frequencies. In turn, the crossover is liable to add to the peak current
demanded by the drive-units. With music signals, a passive crossover stores energy and
can “ kick back ” like a speaker, potentially adding to the speaker’s demands. Overall, for
the amplifi er’s own good, passive crossovers benefi t no less than the drive unit from being
coupled to an amplifi er with very low source impedance, with ample current sourcing and
sinking capability.