Knowledge

The Anatomy of a Compact Disc (CD)

CD’s changed the world when they were introduced offering a compact means to digitally store vast amounts of data when compared to the formats the preceded them.  At first glance a CD bears more in resemblance to vinyl records than to the cassette tapes that it was replacing, but gone are the days of needles and static.  With CD’s your music sounds the same on the 200th play as it does on the first.  You are also able to effortlessly skip and replay tracks with the push of a button.  With all that in mind let’s go over what makes a CD. 

Hub: This is the innermost portion of the disc, made of clear polycarbonate, and is where the disc is mounted in the case and player.

Stacking Ring: On the underside of each disc, this thin ring of raised plastic is used to keep a small amount of space between each disc when stacked up for boxing and/or shipping.

Mirror Band: Generally marked with the manufacturer info or barcode identification.

Data Area: The recordable area that data (music) is stored. The largest reflective surface on the CD where the laser reads the data from “pits” on the metallic reflective surface

The Anatomy of a CD Case

Just like cassette tapes before them CDs came largely in clear plastic cases made from injection-molded polystyrene that allowed for artwork and tracking listings to be displayed.  This guide will cover plastic jewel cases which is how the overwhelming majority of CD’s were packaged.  There exists another style called the “digipak” which utilized folded cardboard packaging with a plastic tray for the disc glued inside.  

Lid: This is clear front portion of the case that is attached by hinges to the back. The insert or booklet contained in here has the album artwork as well other images, lyrics, and credits.

Back: Also clear like the lid the back functions to hold the case together by allowing the lid hinges to lock in as well as providing a place for the tray to snap in.  Artwork with track listing is generally displayed on the back.

Tray & Hub: Early examples tended to have a black tray most switched later in the 90’s to clear.  The teeth on the center hub help to hold the disc firmly in place.