[78-L] Removal of 78 surface noise

[Royal Pemberton]

And isn't the shape of the grooves in a record pressed by a given stamper a
function of the shape and condition of the cutting stylus, the condition and
quality of each of the metal parts used in the production of that stamper,
and the condition and quality of the stamper itself?  So even if you had a
playback stylus that truly matched a given cutting stylus when verified by
checking it with a freshly-cut groove in a wax or lacquer, that's no
guarantee the stylus will match the grooves from a well-worn stamper made
from a tired mother made from a negative derived from an original cutting
the playback stylus may well have perfectly matched.

On Sun, Feb 7, 2010 at 7:34 AM, DAVID BURNHAM <burnhamd at rogers.com> wrote:

> Jeff Lichtman wrote:
>
> Figuring out what part of the groove corresponds to the original
> cutting stylus is worse than non-trivial. Really, if the groove shape
> deviates from the shape of the cutting stylus, how is one to figure
> out where the groove is supposed to be? Knowing the shape isn't
> enough - you need to be able to figure out the lateral displacement.
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> If I understand what you're saying here, the lateral displacement is the
> property which contains the recorded signal.  The process I described will
> locate the groove, or more accurately the cutting stylus' position when the
> recording was made.  The sequence of scans will indicate the lateral
> displacement of the groove.
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Here's a reduction ad absurdum argument. Suppose you have a record
> that is completely wiped out - the original signal has been worn from
> the grooves, so all that's left is noise. It seems obvious that no
> playback system could figure out the original signal - that
> information is gone. It doesn't help to know what the groove shape
> should be because the groove is worn so badly that the groove path
> could be literally *anything* (within the range of the recording
> medium). I maintain that, in the system you're proposing, the
> difference between a completely worn record and one that's only
> slightly worn is one of degree, not kind. Knowing what the groove
> shape should be doesn't necessarily tell you what the signal is,
> because every bit of wear removes some information that may not be
> deducible from the remaining groove.
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> To start off with, a record that is completely wiped out is not a record at
> all.   I'm not going to repeat everything I've written already, but as I
> emphasized in a previous posting, each scan contains no signal information
> whatsoever, the only thing which is accomplished by a single scan is that
> the position of the cutting stylus is established for that instant by any
> portions of the groove wall which correspond to the reference cutting style
> shape.
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