From Steven C. Barr: "...And, no, I have no idea why these numbers were/are
shown on the
labels of commercially-made records"
The matrix number on the label tells the worker in the plant which side (top
or bottom) of which record press to place that particular label on so that
it will be molded as part of the finished record.
Bob Olhsson Audio Mastery, Nashville TN
Mastering, Audio for Picture, Mix Evaluation and Quality Control
Over 40 years making people sound better than they ever imagined!