Compact disc

Extract from the archive: The arrival of the compact disc player


“It makes both the traditional LP record and the tape look positively old-fashioned,” we said, “and like so much today, it wouldn’t be possible without computer technology.

“With normal recording, the movement of the stylus in the grooves is converted into electrical signals, which output from the speakers as noise. On a tape, the magnetic signals are picked up by the playhead, but in both cases there is contact with the recording medium, which means that any imperfections, such as scratches or dust, will be heard in the form of clicks or hissing sounds.

“In the compact disc – it measures 120mm or 4.7 inches in diameter – the recording is printed on one side only, digitally, with the ‘grooves’ at 1.6 micron intervals. stylus or a reading head, the recording is “read” by a laser. Thanks to its highly precise focus, the tip of the beam looks through the thin transparent protective coating, ignoring – simply because it is unable to focus on them – almost any surface damage or dirt. The result is as close to perfecting an amplifier input signal as it is possible to achieve.

“All of this, of course, requires some pretty advanced technology to make it work. For starters, the record needs to be spun between 500 and 200 hours, depending on the game being played.”

For context, a vinyl record is played at 33 or 45 rpm, depending on its diameter.