Re: [ARSCLIST] ET groove cutting ( was "More about ET preservation", was "Comparable collections anywhere?")

[Graham Newton <gn@xxxxxxxxxxxxxxxxxxxxx>]

Scott D. Smith wrote:

> All very good questions! I'm sure Graham will jump in here with some 
> well-informed answers as well, which I would love to hear about.

> Eric Jacobs wrote:

> > I stare at ET grooves all day it seems through a microscope, and I've
> > noticed that some of the groove bottoms are sometimes not as smooth as
> > others - there will be parallel striations, or in some cases the walls
> > look smooth but the bottom is very rough, almost jagged.

You must separate a pressing

from a lacquer (also referred to as a soft-cut, instantaneous cut, or 
incorrectly as an "acetate"... there is NO acetate in them, but that is a whole 
'nother story.)

A pressing can exhibit a wide range of peculiar looking grooves from 
mishandling in the processing and pressing... buffing of the stamper being a 
major contributor to the bottom of the groove looking strange!

In the case of lacquers, remember that before the introduction of magnetic 
tape, the only way to record (other than wire which had its own set of 
problems) was on a lacquer disc.  There were countless different home recorders
and the quality levels varied all over the map.  The lacquer discs for home use 
were often rejects from what a professional user (broadcaster or recording 
studio) would find acceptable to use.

The BIGGEST problem was that most people trying to cut a disc NEVER read the 
"how to " manual and didn't have the foggiest idea of how to do it right.
They cut using chipped styli, worn styli and styli that had cut so deeply that 
it hit the disc's base material, usually aluminum.  Worse, they often had the 
cutting head and stylus mis-aligned to the surface of the disc.  The resultant 
grooves bore the scars of the mistreatment and that consequently, is what you 
often see when looking at a groove under a microscope.

Additions to these problems were caused by people who never changed a worn 
stylus on their playback equipment and added scoring to the grooves.  This is 
why you often can play only one groove wall (stereo cartridge and stylus, of 
course) and get a much more quiet result than playing the mono sum of both.

In the above, I am referring to mono discs, where stereo presents its own set 
of peculiar problems.




... Graham Newton

--
Audio Restoration by Graham Newton, http://www.audio-restoration.com
World class professional services applied to tape or phonograph records for
consumers and re-releases, featuring CEDAR's new CAMBRIDGE processes.