Abstract: An audio loudspeaker comprises: an enclosure; at least two driver units mounted within the enclosure; crossover circuitry located inside the enclosure; and a plurality of input terminals located on the exterior of the enclosure. The input terminals include: first pairs of terminals for each of the driver units, each of the first pairs being connected directly to a respective one of the driver units; a second pair of second terminals having a first crossover circuit connected therebetween and normally electrically isolated from the driver units; and a third pair of third terminals having a second crossover circuit connected therebetween and normally electrically isolated from the driver units. Connector elements are used for interconnecting selected ones of said first, second and third terminals, externally of said enclosure, whereby the crossover circuits may be selectively connected in circuit between one or more of the first terminals and one or more of the driver units.