Apparatus and devices for recording, transmitting and reproduction of sound; amplifiers; preamplifiers of sound; audio mixers; apparatus and installations for public address; equalizers, namely, sound equalizers and graphic equalizers; sound filters, namely, electronic devices for selecting an audio signal by frequency bands; radios; radio receivers; radio signal tuners; recorders of sound using magnetic tapes; recorders of sound using compact disks and optical disks; audio cassette players; ...