degradation/dcc

[Dick Locke <wiltel!dlocke@uunet.UU.NET>]

The question of "Do CD's degrade, and if so over what period of time?" is
a matter of some debate.  The manufactures will claim that the discs
should remain playable with proper handling and storage for about 1000
years.  Mobile Fidelity claims that their gold cd's (they use gold
instead of aluminum) should last > 10,000 years.  In my opinion, it
is very likely that a CD will last longer than any form of tape.

The claim that CD's might become unplayable after 7 or 10 years is thought
to be based on some problems experienced with laser discs (like, the
big 12" discs they use for movies) that experience "laser rot".  Laser
discs are actually two discs glued together, and there were some
fairly significant problems where the 2 discs weren't sealed properly 
the discs would become unplayable.  Problems of this nature apparently
are rare today.  Since audio CDs are one-sided only this can't happen to 'em.

I think a person responding to the post was confused because he was
talking about DAT, which has been around for a few years by now, and
the NEW DCC (Digital Compact Cassette) which is totally different and
incompatible with DAT.  DCC machines are expected to cost about $1000
US dollars when they become available.

DCC machines, unlike the CD or DAT format, use a data compression
algorithm which PUPOSEFULLY REMOVES SOME MUSICAL INFORMATION in order
to fit all the bits on the relatively low capacity tape.  Thus,
CD is an inherently more musically accurate medium.  DCC is targeted
to eventually replace the plain old analogue cassette.  Since there
are already so many analogue cassettes and players, the manufacturers
have decided to make the new machines able to play (only) the analogue
format cassettes.  DCC's are generally thought to be sonically
superior to the average analogue cassettes.

Hope this helps,

-Dick (vinyl lives!) Locke