Organization: North Dakota State University, Fargo, ND
Lines: 30
In article <1992Jul24.203724.22543@rchland.ibm.com> jsimon@rchland.vnet.ibm.com (Gerald Simon) writes:
>This may sound stupid but, when I look at the back side of a CD (the side
>the music is on), the light reflected back in the first part of the CD
>(usually less than 1/4 inch from the outside) differs from the light reflected
>back from the rest of the CD. I've always assumed that's the portion of the
>CD where the music is recorded. If that assumption is correct, than there is
>a LOT of space left over for additional music over the rest of the CD....How
>wrong am I?
I don't know which part you think is the recorded part and the unused part,
but CD's are played from the center out, the opposite of records. So the
band around the outside edge is the unrecorded part.
I have noticed the difference in appearance, and I have also noticed that
the shorter the playing time of the CD, the bigger the band around the edge
is.
Also, believe it or not, the recorded part has a smoother appearance than
the unrecorded part. On most of my CD's the recorded part has a very smooth
looking surface, with a little speckly apparance, and the unused part has
what looks like rings, or very small, close "record" grooves. These grooves
are probabably caused by the finishing process used on the metal disk.
Maybe it is machined in a rotational fashon, making the circular lines,
which are later removed in the recorded part by the pressing...
Anyway, my Wierd Al CD, which is about 50 minutes long, has a half inch band
of unused space around the outside, but my Guns 'n' Roses Use Your Illusion II CD is 76 minutes long, and has an unused band less than 1/16th of an inch
around the outside edge. So 76 seems to be near the limit, and the band
