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----- Original Message -----
From: "Rob Spencer" <[log in to unmask]>
> In any event, the typical pre-tape 78 was recorded direct to disk, ore
> or less, so unless there is access to the original metal parts or an
> intermediate form, the record itself is the lowest-generation copy
> available, so we are faced with the necessity of tracing its groove in
> one way or another.  In theory, the process discussed herein would seem
> to allow the most accurate extraction possible of the information
> represented by the groove.  At the least, it would allow the
> reconstruction of a mint copy of any record that has a groove that is
> pristine at some level all along its length.  This last consideration
> alone is enough to justify it for me.
Is not the analog signal...or, in any case, the analog signal as it would be
heard playing the original record...essentially defined by the path followed
by the exact centre of the groove? Thus, if an image could be obtained which
would allow the determination of that path (and I lack the expertise to
figure out how that could/would be done) then the original waveform as
recorded could be established and replicated. In this case, there would
only be problems if either the actual surface of the record had been
distorted in such a way that the groove no longer followed its original
path, or if a portion of the groove was actually missing due to substantial
damage to the record surface. It seems to me there are three possible
demarcations that might show up in an image: the left and right points where
the groove intersects the actual record surface and the center point where
the left and right malls intersect. Am I correct, or are these not actual
demaractions (in the sense that they are curved rather than the intersection
of planes)? If the latter, would there be an identifiable and thus
followable
path in an image of the surface created by shadowing, or is this so gradual
that it couldn't reliably be identified and followed?
Steven C. Barr