Re: Do CD's Degrade?, and DCC Question

[neilg@sfu.ca (Neil K. Guy)]

mujad@uxa.ecn.bgu.edu (James A. Drenter) writes:

>In simple terms, yes it is currently believed that CDs begin to oxidize
>after as few as 10 years. [...]

 If you want to see this right now, hold an older CD up to a bright
light. You'll probably see a number of bright points of light on the
disc. Those pinholes are apparently spots where the aluminium has
oxidised and is thus transparent. In fact, if you look at one of the
early CDs, which were made when oxygen contamination was more of a
problem than now, you'll see quite a peppering of little bright
pinholes. (for some reason these pinholes always give me the
creeps...) So one day all our CDs may well be totally clear and thus
unplayable.

 I hear also that a number of very early CDs used poorly formulated
paint for the lettering on the front, which ate away at the
polycarbonate. (the silkscreened side of the CD is the thin side,
closest to the actual aluminium coating.) Supposedly this is no longer
a the case.

 This is usually not a major problem, especially with higher quality
players. Good CD players with a decent tracking mechanism can
accurately track the laser and compensate for data loss by filling in
the gaps - extrapolating your favourite Kate number. So when you
listen to a CD a small percentage of the sound you hear was never made
by Ms. Bush at all, but is a kind of computer best guess. Sort of.
However, cheaper CD players often skip and otherwise choke on badly
pinholed CDs. You can try this by putting thin strips of black tape on
the shiny side of a CD, from centre to edge (radially). Lousy players
can't play a CD with a strip of tape on it, good ones can sometimes
compensate for a few strips. Of course, this can be risky thing to do
as you can completely wreck a player if the tape comes loose, so
forget I ever said that.

 If you're *really* worried about this sort of thing, you can always
buy gold CDs which don't oxidize. The life of these discs is limited
by the lifespan of the polycarbonate plastic itself.

>Incidentally, don't expect those new DAT decks to play your current
>standard cassettes, they won't.  The DAT standard is a completely
>different type of tape (physically, as well as operationally).  It is
>thicker, and resembles more of a small video tape (such as VHS-C).  DO
>NOT BUY A DAT SYSTEM IF YOU'RE NOT GOING TO USE DATs EXCLUSIVELY.

 I think the original poster was asking about the Philips DCC system,
not DAT. DCC is supposed to be able to play ordinary compact cassettes
(analogue flavour) as well as a new DCC digital variety. DATs, as you
point out, cannot play regular cassettes at all. It's a shame that
DATs haven't caught on and probably won't, as they sound darn good. I
suspect they'll be like Betamax - good technology killed by marketing.

 - Neil K. (n_k_guy@sfu.ca)

 (disclaimer. I'm no expert on this stuff. I've picked up this through
reading the odd audio mag and books on the subject of CDs and the
like. Corrections appreciated should I be wildly wrong on anything)