When Numbers Get Serious

When Numbers Get Serious

Codes and matrix numbers … or how to sex a budgerigar. 

At the start of this project, the idea was I wouldn’t get hung up on catalogue numbers, nor list them. As time passed it became clear that it’s the only way to note reissues and various editions of a track, or to place tracks in sequence within a label. So catalogue numbers were retro-fitted. The catalogue number on a sleeve indicates that the record was sold in it initially. You can only be 100% certain if you bought it yourself, or a known and trusted source did. There are anomalies all over the place suggesting that design changes were not smooth transitions. EMI are more confusing than most in having stuff appear in sleeves abandoned six months earlier.

Major artists are the best route to finding out about a label. The Beatles for Parlophone, Elvis for RCA, Cliff Richard for Columbia, The Beach Boys for Capitol, Bob Dylan for CBS. There are lots of examples about and also the discs were on sale as “new” for many months or even years. That means that people try to track down the first release. This is where it gets arcane.

There is information etched onto the run-out groove of records. You will need a strong light. You may need a magnifying glass.

Matrix numbers

The matrix number is the true reference number of the individual song or track. It differs from the catalogue number, and will remain constant through reissues. The catalogue number refers to the disc itself, so is the same on both sides.

Matrix numbers are usually assigned at the time of recording. If the matrix numbers were sequential, such as 23567 and 23568, it’s a fair bet that the lower number is the A side. However the matrix numbers may vary considerably on both sides of a single, in which case the lower number may not be the A-side.

Some labels also print the matrix number in a smaller font next to the catalogue number on the label, often upside-down to distinguish it. For one Columbia release, the matrix number 7XCE 24786 45 breaks down like this:

EMI 7 matrix codes

Mother and stamper codes

A record before 1950 was recorded directly to master disc. Then tapes took over, and a master disc was made from the tape. Mastering was as much art as science, with the mastering engineer manually adjusting the groove cutter to allow for changes in sound. The master number was etched onto the runout area. In the early days the master was coated and used to press records, but soon they found they needed multiple masters and these were called mothers.  A mother was a sub-master. From the mothers, they created stampers which actually sat in the machines pressing the records. The mother could be used to make many stampers before it wore out, and a new mother was required. 

Stampers were electroplated nickel casts from the mother.  One was used for each side of the disc. They had a relatively short life before wearing out, and many were used simultaneously to press large numbers of hit records. The life of a stamper might have been as short as 300 discs, and not much longer than 2000. Hi-fi LPs would have been produced at a lower stamper-to-disc ratio than the run of the mill. Budget labels had a far higher stamper-to-disc ratio, and this is audible. Often the earliest runs, going to DJs and promotion, would be deliberately done at a low stamper-to-disc ratio, such as 300. This explains (partly) the value of DJ copies. They are, or could be, better.

The mother number, and the stamper number trace a disc back to a particular mother. On EMI discs, the mother number is etched on the run out groove at approximately the 9 o’clock position. The stamper is identified by letters at the three o’clock position.  In theory, an early stamper meant that the mother had suffered little wear, though in practice mothers were discarded and replaced early enough for it to make little difference, though “wishful hearing” is an audiophile affliction and some will be convinced that earlier stampers sound better.

Stamper codes

For all EMI labels, the letters in GRAMOPHLTD represent numbers:


So if 2 is etched at 9 o’clock, and AH at 3 o’clock, the record derives from the 2nd mother, and the 37th stamper. For a Beatles fanatic, 1  G would mean 1st mother, 1st stamper, so one of the first 300 copies ever pressed. The Island and Charisma labels conveniently adopted the same code reference system.

If there’s a letter outside GRAMOPHLTD (such as “J”) it will signify a demo stamper.

The Decca group used a similar system, also at 3 o’clock,  with the word BUCKINGHAM, a town beloved of limerick writers.

Buckingham code

The EMI and Decca codes are well-known. Beatles collectors drive the interest in EMI (with Cliff and The Shadows adding a little extra). London-American collectability, together with Elvis on Decca-pressed RCA and Rolling Stones on Decca mean interest in Decca codes.

In the early 60s, the other three pressing plants were Pye, Philips and Oriole / Embassy. They may have used similar systems, but they are obscure because there’s nothing on the labels with the massive collector value of The Beatles. Oriole-American is massively collectable, but there are very few copies and they’re all valuable. CBS bought Oriole solely for its pressing facilities.

It’s only when there a million copies swashing around the system that the fanatics start trying to rank the collectability of individual discs.

Contract pressings for EMI

EMI contracted pressing out to its rivals when there was a rush on, and Oriole in particular was contracted to press Beatles singles (they’re thicker). They bear no stamper codes. Beatles collectors seek out the different pressings, judging the origin by the style of the push-out centres and the feel of the outside edge. Some discs come to a point at the rim, some to a squared off edge, others are rounded. Other labels did the same with runaway hits. So ignoring what’s printed on the label, there are ways of detecting the pressing plant for EMI discs (Parlophone, Columbia, Apple).

EMI contract pressings

Tax Codes

Tax codes were stamped on British pressed records, showing the rate of purchase tax applicable at the time the record was pressed. These rates were particularly volatile in 1962 and 1963, thus narrowly dating the time a record was pressed, which is particularly interesting to Beatles collectors, as it covers their early records. PT and KT were EMI price rise dates rather than increases in purchase tax.

Record tac codes

Matrix number … not just The Beatles

My Mind's Eye matrix number copy

The matrix number on My Mind’s Eye by Small Faces, Decca,  1966, ends in T1-1C, which means it’s the withdrawn first mix. Mint value £30. If it says T1-2C it drops to £10.

American run-out codes

These are much the same, just that there are more of them. Major labels pressed in several locations, and collectors can detect which plant pressed a disc, and no doubt can spend hours trying to work out whether they sound different. Because Beatles collectors are the most fanatic, Capitol are first in the lists, and they also pressed for Warner Bros. They had four pressing plants:

Los Angeles – ☆ for Capitol, plus 5 mono, 6 stereo.  LW for Warner
Jacksonville, Illinois – 0  or () for Capitol, JW for Warner
Scranton, Pennysylvania – Ƨ for Capitol
Winchester, Virginia  – —◁ for Capitol

You can find lists online for all American labels – remembering that many labels commissioned those with plants to press for them.

Look at the auction details for an autographed copy of the White Album, which was sold in 2013 for $200,000:

The side opening sleeve is numbered 2595599 which makes it a Los Angeles Bert-Co 1968 second pressing. The vinyl is a Jacksonville pressing. The numbers on the run off groove are as follows: record 1 – Side 1, SWBO-1-101-J59 #2; record 1 – Side 2, SWBO-X2-101-J49 #3 2; record 2 – Side 3, SWBO-3-101-J55 #1; record 2 – Side 4, SWBO-X4-101-J48 #1. Each record is housed in a white inner sleeve. The vinyl itself is in very good condition, the record labels are in near mint condition. The poster and the photographs are in very good condition.


The cartoon illustrations are fifty years old (from Helen Shapiro’s Own Book For Girls), but they show record manufacture back in 1962, and explain master, mother, stamper, matrix. The “some people who have a copy” at the end of the story are the DJs who have demos.  

record manufacture 1

record manufacture 2