Matrix numbers

A matrix number is an alphanumeric code (and on occasion, other symbols) stamped or handwritten (or a combination of the two) into the run-out groove area of a gramophone record. This is the non-grooved area between the end of the final band on a record's side and the label, also known as the run-off groove area, end-groove area, matrix area, or "dead wax".

A matrix number is intended for the internal use of the record manufacturing plant, but they are also studied and documented by record collectors, as they can sometimes provide useful information about the edition of the record.

There are two parts of the matrix number to be considered: the main number, which is usually printed on the label as well, and extra information which can include a cut or take number. Matrix numbers can refer to any of these elements, or all of them combined. The inscription area may also contain record plant codes or logos, the initials or signature of the disc cutting engineer, and cutting or copyright dates, among other things.

The matrix number printed on the label should not be confused with the catalogue number, which is usually in larger type, and will typically be the same number on both sides of the record. Matrix numbers will be different on each side, and are sometimes printed upside down on the label to prevent them from being mistaken for the catalogue number.

The purpose of the main number is to assign a filing number to the stamper, and to ensure each side receives the proper label, by visually comparing the number on the label to the inscribed number.

The most important part of the extra information is usually the cut number, which is a suffix to the main number. For example, matrix number 12345 is seen on a label, but examination of the run-out groove area reveals number 12345–3, which indicates this is the third cut of this side. It is not unusual to find records with a different cut number on each side.

Sides are recut for various reasons. Record stampers can only be used to make so many copies before they become worn, and a new cut is required. (As of the early 1980s, this was no longer true. Changes to master disc manufacturing methods, including the DMM or Direct Metal Mastering system, made it possible to make many copies of a master cut non-destructively, so a recut was no longer necessary when the plate used for pressing became worn.) Stampers can also become damaged from handling. Recuts can also be made when there is a problem with the previous cut, for example, a technical fault or improper banding (the visual separation between songs). When a new cut is made, several copies called test pressings are made for technicians (and, for a new record, the producer and the recording artist) to review the cut, and determine if it should be accepted or rejected. If it is rejected, another cut must be made.

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