Loudspeakers, loudspeaker cabinets, loudspeaker racks, loudspeaker systems, control apparatus and equipment, namely, electronic controllers, signal processors and sound equalizers for loudspeaker systems, electronic controllers for loudspeakers, amplifiers, crossover networks consisting primarily of sound equalizers and crossovers, apparatus for recording, transmission and reproduction of sound and images, microphones, sound reverberation units consisting primarily of audio amplifiers, comput...