Radio transmitters and receivers; audio-receivers and video-receivers, sound transmitting apparatus, sound reproduction apparatus, cassette and CD players, microphones, amplifiers and preamplifiers, Loudspeaker systems, Loudspeakers with built in amplifiers, Public address systems, Public address and sound system accessories, namely, microphones, loudspeakers, microphone cables, speaker cables, and sound mixers; and cables for electrical or optical signal transmission