[78-L] How a Columbia Record is Made (silently)

[Michael Shoshani]

On Thu, 2010-10-07 at 10:38 -0700, Michael Biel wrote:

> There is some info on [spiral-out grooves] in the aforementioned diaries of Harry O.
> Sooy.
> 
> http://www.davidsarnoff.org/sooyh-maintext1921.html
> 
> 1922: "August 30th: Instructions were issued by Mr. Royal in accordance
> with his desire to carry on some experiments to perfect an eccentric
> groove at the finish of master records, connecting with the record
> groove, for the purpose of operating an automatic brake. There were one,
> two and as many as three grooves tried on a number of records, but two
> grooves proved the best for various reasons, and were accepted as
> satisfactory December 5, 1922.

One thing I noticed on my Victrola with automatic brake: if you set it
using the inner eccentric groove, when you started the turntable the
part that was tripped actually cocked back the distance between the
grooves. The inner groove "set" the brake, but the outer groove actually
tripped it.


> "August 31st: After successful experiments with Eccentric Grooves, on
> this date we discontinued putting the concentric groove at the finish of
> the record spiral.

Just a quick note to any who may be confused: by "record spiral", Sooy
means the music groove of the record. Victor did not employ a spiral-out
groove until the 1930s.

> 
> "December 2d: A problem confronted us as to just how we could put
> eccentric grooves in the metal moulds and our stock matrices....

> "May 1st, 1923: In a conference with Mr. Royal, instructions were issued
> to proceed immediately to double the Red Seal Catalog, (that is,
> double-face them) and equip them with Eccentric grooves. Red Seal work
> was to precede Black Label class, which meant rolling Concentric groove
> out of Master matrix, and Eccentric groove put in a shell of each
> selection selected to be doubled, and give them new Catalog numbers. 

This seems to indicate that, for retrofitting older Red Seal records
with the eccentric grooves, they buffed the concentric groove out of the
original metal negative, plated a new positive mother from that matrix,
then cut the eccentrics into the new mother. Am I following this
correctly? (I'm presuming that for new recordings, the eccentrics were
cut into the master wax record.)

Were catalog numbers punched into the matrix? I'm presuming they were,
since they are raised rather than engraved on the finished record. I've
seen some reissues wherein the original catalog numbers were very
carelessly obliterated - in some cases no more than a strikethrough -
with new catalog numbers either beside the old one, or even on top of
it.

MS