On Thursday, April 02, 2009 11:10 AM, Michael Biel wrote:
Victor and other companies routinely polished their masters or
stampers with jeweler's rouge which probably removed the rough
edges of the sound wave -- namely the high frequencies. George
Brock-Nannestad discovered a document at EMI that discussed
Victor running a knurling tool thru the grooves to likewise
smooth them out.
There is evidence that Victor "dumbed down" their recordings,
so it is important that you have access to those test pressings
which might not have been compromised. But maybe some of the
things Victor was polishing off were cutter-head transient
Mike, you've got me thinking more about the manufacturing
process - thanks!
I have noticed on these test pressings that the outer edge/rim
of the disc was manually ground down - quite roughly I might
add. The edge is even chipped, presumably from the grinding
process. Not all the discs were roughly ground down in this
matter, some have the smooth outer edge that you normally find
on commercial discs.
The grinding is quite non-uniform - to the point that the radius
of the disc varies by as much as 1/8-inch (3 mm) even though
the spindle hole is properly centered.
If it matters, these test pressings are single-sided web-back
I also have the Victor QA/QC label from the back of the disc.
Most of these are not filled out, but I am curious what all the
abbreviations mean and how these were used. I have an image
scan (jpeg) of one of these for those who are curious.
Looking for more hints and enlightenment on how these test
pressings might have been manufactured...
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