Last Updated on 25 February 2026 by Massimo M.
One of the most reliable ways to determine whether a record is an original pressing is by examining the numbers and inscriptions engraved in the vinyl run-out, also known as the dead wax. In this guide, we explain what matrix numbers are, how to read them correctly, and why they are essential for identifying first pressings, reissues, and special editions.
If you want to know how to recognize the original pressings of vinyl records, I recommend you read my guide written specifically on this topic.
What Is the Run-Out (Dead Wax) of a Vinyl Record
The vinyl run out sector aka dead wax, it’s the phisical area of disc between last groove and the label
In this space are hand engraved or printed some letters or numbers, the matrix numbers. These elements are written into the run-out mainly by mastering engineers, cutting engineers or disc pressing plant technicians. These matrix codes are used to identify the printer, engineer and pressing factory.
Matrix numbers are part of the group of elements that must be mastered in order to recognise original vinyl record pressings.
What are the matrix numbers engraved on vinyl discs?
Matrix numbers are basically unique identifiers that were originally used by those involved in the physical production of the disc, but today they will tell you everything you need to know about your album: where it was made, when it was made and, in some cases, even the person responsible for pressing your album. This information, together with the disc’s catalogue number, will help you to identify exactly which version of the album you own or would like to purchase..
How to read matrix numbers step by step
The letters and numbers written are obviously not random. Each one has its own specific meaning. Below are some examples:
A1 B1: A common code among early prints. Variants may include codes such as
A//1 B//1 o A-1 B-1. Of course, the numbers in these codes may change from one publication to another.
YEX/YAX: Commonly found on records by artists such as The Beatles, Queen and Pink Floyd. These prefixes often indicate that the associated record used stereo audio.
XEX: Widely used with the same publications as YEX and YAX, however, an XEX code normally indicates that the disc was pressed in mono.
1Y//1 2Y//1: This code often indicates a first pressing and can be found on discs by Cream, Rush, and Genesis.
XZAL: This code is often followed by a series of numbers depending on the publication in which it appears. It is often found on Rolling Stones records. It should be noted that for the Rolling Stones, as for the Beatles and other bands of the so-called English invasion, there is a further complication in identifying copies of the first albums produced. The discographies of these two bands differ on records with the same title but released in the UK or the US. See the discographies of the Beatles and the Rolling Stones with a list of the same records released in the UK and the US.
A* B*: A rarer variant of the A/B matrix that often contains no numerical information.
In some cases, artists or record labels include entire sentences or phrases alongside a record’s matrix numbers. For collectors, these can be fun to discover, adding an extra layer of intrigue to the vinyl experience. Most of the time, however, these are actually signatures that mastering engineers have left on their work, much like an artist signing a painting.
Popular phrases and names to look out for include ‘A PORKY PRIME CUT’, “TOWNHOUSE” and ‘BOPPIN’ BOB’. ‘Boppin’ John Robert Jones began his career as an audio mastering and cutting engineer in the 1960s with Decca Records, where he remained until 1968, when he moved to Madrid to work for Discos Columbia until 1975. Townhouse, on the other hand, refers to an engineering and mastering studio located near Shepherd’s Bush in London, with over 12,500 credits on Discogs! It was built by Richard Branson and boasts some of the highest quality record pressings. Among the most notable artists to have recorded at Townhouse are Kate Bush and Queen. Well known for his run-out grooves, Porky is the nickname of an engineer named George Peckham. He began his career in 1968 as an apprentice record cutter at Apple Studios and ended up with his own studio called Porky’s Mastering Services, where he cut some of the most important records of the 1980s.
Matrix number and first print: how to check
In the world of vinyl collecting, the term ‘first pressing’ is often surrounded by an aura of mystery (and unreal prices). But to understand whether you have a piece of history in your hands or a trivial reissue from the 1980s, it is not enough to look at the cover, as I explained in detail in the article How to recognise an original first pressing.
Here’s what you really need to check so you don’t make a mistake..
The myth of the low number
One of the most common mistakes is equating a low matrix number with the first pressing. Although in many cases a code ending in -1A or -1S indicates the first lacquer cut, this is not a universal rule.
Some pressing plants used several machines simultaneously, or shipped different matrices to various countries for global distribution. A low number indicates the disc’s proximity to the original master (which is great for sound quality), but does not guarantee that the vinyl was released in stores on the first day of release.
Seek total consistency
To correctly identify a record, you need to act like a detective and look for consistency between three key elements:
- Catalogue code: The one printed on the back of the cover. Learn more by reading the article on record catalogue codes.
- Label: The design, colour and legal text (rim text) must correspond to the era of release. For example, a changed logo or a different record company address can reveal a late reissue.
- Run-out (Matrix): The hand-engraved or printed text in the empty space between the end of the last track and the label. This is where the “DNA” of the record lies.
If the code on the cover says one thing and the matrix says another, you may have a “mismatch” or a copy assembled from parts of different editions.
Comparing with the database (Discogs)
In this search, your best friend is Discogs. Don’t just search for the album title; type in the alphanumeric code found in the run-out groove.
Pro tip: Pay attention to the smallest details. A misplaced comma on the label or the signature of a particular sound engineer engraved in the groove can make the difference between a £10 record and a £200 one.
FAQ matrix numbers
What is the difference between catalogue number and matrix number?
The catalogue number identifies the album commercially, while the matrix number identifies the specific recording on the disc.
Do matrix numbers guarantee that a vinyl record is original?
No, but they are one of the most reliable elements when compared with the label, cover and period of printing.
Can two vinyl records with the same catalogue number have different matrix numbers?
Yes, and this is very common: it indicates different pressings or reissues.
Where exactly are the matrix numbers located on a vinyl record?
Matrix numbers are engraved in the space between the last track and the centre label of the record, called the run-out or dead wax.
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