Well, if it were a very rare 78, it would probably be a pressing from the first
and only stamper (since they'd only make multiple stampers for records which
sold in huge numbers), so it would not be "many generations removed from the
original groove". It would be as close to the groove on the metal stamper as you
could possibly get. I don't know of any property of shellac which resembles what
you describe, but of course the quality of the shellac varied widely, and was
especially poor during WWII when old 78s were ground up and reused.
As for "baking in" the surface noise: the negative would simply copy the surface
noise of the positive, neither increase nor eliminate it.
A 78 stylus normally rides on the two groove walls of a pressed disc, and doesn't
usually touch the very bottom of the groove. However, the groove walls of a 78
which has been played to death with a heavy and dull needle may be damaged so
badly that the stylus reaches the very bottom of the groove and obliterates it. My
idea would only work when the very bottom of the groove is still intact.
The two tips of the bi-point stylus do ride on the walls the inverted groove, where
the wear is worst, but by choosing a small enough bi-point, it might be possible to
capture just the tip of the ridge (the very bottom of the original groove), where
the damage would often be much less. I agree, this may be wishful thinking ;-)
I agree that optical scanning still holds much promise (the Library of Congress
is about to scan a broken glass disc for me).
[log in to unmask]
> Date: Sat, 24 Nov 2012 10:09:07 -0500
> From: Tom Fine <[log in to unmask]>
> Subject: Re: Stuff of which dreams are made
> Hi Doug:
> I was thinking about this concept. Do you think you'd get a well-defined enough negative of the
> groove to play it back? It seems to me that you're so many generations removed from the original
> groove that what you end up with will be too physically different and distorted to sound any good. I
> thought one of the problems with shellac is that it ends up with a non "sharp" reproduction of the
> groove. Plus, wouldn't you be "baking in" surface noise from the non-smooth shellac surface? I was
> thinking using optical scanning and "photoshopping" the resulting image, you could sharpen up the
> groove's pitch and path and also "erase" the roughness of the walls and bottom.
> -- Tom Fine
> ----- Original Message -----
> From: "Doug Pomeroy" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, November 23, 2012 10:53 AM
> Subject: Re: [ARSCLIST] Stuff of which dreams are made
> Indeed, a machine cannot create out of thin air something it "thinks" is "missing", but
> the technique of interpolation (now more than twenty years old) can often provide a
> convincing fill-in. I believe Sonic Solutions' NoNoise was the first, followed by processors
> from CEDAR and many others using versions of the basic idea: analysis of the music
> before and after an audio disruption, be it a "click" or scrape or whatever, can give the
> computer enough information to synthesize something like the missing music. This
> doesn't always work, of course, especially if the texture of the music is rapidly changing,
> or if the duration of the disruption is very long.
> The device (IRENE) which Carl Haber developed is a unique tool, originally developed
> for playing vertical recordings, but the audio quality has, so far, been less than ideal.
> One idea which might prove fruitful, would be to make a new negative impression from
> a worn 78, and plate it and play the plated metal part with the bi-point styli designed for
> playing negatives. The idea here is that the ridge on the negative represents the very
> bottom of the original groove, and since most groove wear is on the sides and not at
> the very bottom, this might allow a cleaner transfer of the music.