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Re: [ARSCLIST] Retro Vinyl CDs
At 12:04 PM 5/4/2003 +0200, George Brock-Nannestad wrote:
----- I can see confusion indeed, because I do not know any mechanical
recordings actually pressed in polycarbonate. However, pressing in
polycarbonate is a part of the ordinary Audio CD manufacture (and actually
the wobble track in CD-R is pressed too). Incidentally, as a gimmick, I
have cut 78 rpm grooves in the outer parts of the clear side of a CD-R,
giving me a maximum of 90 seconds of sound, while the CD-R contains the
same selection as an only track in a digital form. Using 33 1/3 rpm and
400 grooves to the inch would give quite a self-contained archival medium:
when the digital part of the CD-R breaks down after the 361 (or whatever)
years, we still have the mechanical version to play.
The Verbatim discs are necessarily compliant with the CD standard and
therefore no more than 12 cm in diameter. A disc of the dimensions of a
"45" (half again as wide) could not be inserted into, or read or written by
a Compact Disc device.
Both sides of some blanks are clear. My guess is that George refers to the
upper surface with an acrylic lacquer over the metallizing rather than the
lower which is polycarbonate. In that case, extreme caution is needed for
any incision: the layer is thin and fragile and any damage to the metal
layer is fatal to the (optical) recording. An overcoating will reduce the
risk, of course.