Apparatus for reproduction of sound, apparatus and devices for use in public address sound systems, loudspeakers, loudspeaker cabinets, loud speakers with integrated sound amplifier, sound amplifiers, apparatus for processing sound signals, sound filters, signal compressors, amplitude limiters, equalizers, anti-distortion devices, attenuators, tone control apparatus, frequency dividers, apparatus for controlling public address sound systems, parts and fittings of the aforesaid goods, namely stands, cables, racks, patchbays and power distributors