How to Read Vinyl Matrix Numbers & Runout Codes

The matrix area is the smooth, ungrooved ring of vinyl between the end of the last playable groove and the outer edge of the label. On 12-inch LPs it's typically about 1.5cm wide. On 7-inch singles it's narrower. The codes are either etched (hand-scratched with a stylus during mastering) or machine-stamped (impressed during the pressing process).

To read the codes:

1. Hold the record at roughly a 30-degree angle to a bright light source (a desk lamp or your phone flashlight works)
2. Rotate the record slowly so the light catches the etched marks
3. Use a magnifying loupe (5x-10x) if the codes are faint or the etching is fine
4. Read around the entire circumference — codes are often scattered, not lined up in one place

Both sides matter. The matrix on side A is different from side B (each side was cut separately at the lathe). Read both. Sometimes one side will have a clearer code than the other, especially with worn pressings.

What to actually look for

You're scanning for three kinds of marks:

• A matrix string — usually contains the catalog number or release ID, a side identifier (-A, -B, sometimes -1, -2), and one or more take/cut numbers
• Engineer signatures or plant codes — initials, names, or recognizable etched symbols
• Mother and stamper numbers — single letters or small numbers indicating which production part was used

A typical Blue Note 1960s matrix might look like: BST-84163-A-1 RVG etched into the deadwax of side A. That decodes as: catalog number BST 84163 (the Joe Henderson Inner Urge stereo release), side A, first cut, mastered by Rudy Van Gelder at his New Jersey studio.

Recognizing what's in front of you is mostly a matter of having seen enough deadwax codes to know the patterns. The first hundred records you look at carefully will teach you more than any guide.

Beyond the matrix string, many pressings include single letters or numbers that identify the mother and stamper used to press your specific disc. Understanding this requires a quick detour into how records are physically made.

The chain from master to your record

When an album is mastered for vinyl:

1. An engineer cuts a lacquer master — a soft aluminum-and-lacquer disc that becomes the original cut. There's one per side
2. The lacquer is electroplated to create the father (a metal negative — playing surface inverted, hills where the lacquer had grooves)
3. The father is plated again to create the mother (a metal positive — same as the lacquer, but durable)
4. Multiple mothers can be made from one father if needed
5. Each mother is plated to create stampers — these are the parts that actually press your record. Stampers wear out after several thousand pressings, so each mother typically produces many stampers
6. Each stamper presses many records

What the codes look like

UK pressings (especially EMI, Decca, Philips) often etch a letter that indicates the mother, plus a number for the stamper. The classic EMI system uses the word "GRAMOPHCO" or "BIEMRECORD" with each letter representing a number 1-10. So a stamper code of G would be 1, R would be 2, A 3, and so on. A pressing with stamper code G/A is from mother 1, stamper 3.

US Columbia plants used a different system — usually a small letter near the catalog number indicating the stamper batch.

Why this matters

Stampers wear over their pressing life. The first few hundred records pressed from a fresh stamper sound crisper than the last few hundred pressed before the stamper was replaced. Low stamper numbers (the earliest pressings off a given stamper) are often considered the best-sounding pressings of any given run.

The relationship isn't always linear — a label might cut multiple stampers in parallel for high-demand albums, so "low number" doesn't always mean "earlier pressing." But within a single pressing batch, low mother/stamper combinations are usually a positive sound-quality indicator.

This is exactly the kind of detail that the parent pillar on vinyl identification summarizes; if you want the deeper dive into how mother/stamper progression interacts with label-variant changes, that's where the cross-reference table lives.

The third class of mark you'll see in deadwax is the engineer's or plant's signature. These are often the most valuable to recognize because they directly affect price — certain engineers cut audibly better masters, and collectors pay premiums for their work.

Engineer signatures

• `RL` (Robert Ludwig) — Sterling Sound, NYC. RL-cut pressings of 1970s rock are among the most collected. The RL Led Zeppelin II (Atlantic SD 8236, the "Brown Bomber") is the textbook example: NM copies trade at $400-$1,500 versus $40-$80 for non-RL cuts of the same album
• `STERLING` (in block capitals) — cut at Sterling Sound, NYC (not necessarily by Ludwig). Generally indicates a careful cut
• `PORKY'S` or `PECKO` or a hand-drawn pig snout — George Peckham at Apple Studios, London. Peckham cut many Beatles and Apple-era pressings. The PORKY signature is a positive sign of a careful UK cut
• `KENDUN` — Kendun Recorders, Burbank, CA. 1970s rock cuts
• `MASTERDISK` — Masterdisk, NYC. Often associated with Bob Ludwig's later work after he left Sterling
• `MoFi` or `MO_FI` — Mobile Fidelity Sound Lab. Audiophile reissue series
• `RVG` — Rudy Van Gelder, the legendary jazz engineer who cut nearly every Blue Note classic, plus Prestige and Impulse releases. RVG in the deadwax of a 1950s-60s jazz pressing is what you want to see
• `PR/RVG` — pressed by Plastylite from an RVG cut. Plastylite was Blue Note's main pressing plant until 1966; the PR mark looks like an ear (the "ear" that collectors talk about) and confirms a true Plastylite-era pressing
• `A1/B1` with no other marks — common on UK pressings to indicate the very first cut/take of each side. Strongly suggests a first pressing
• `Bilbo` — a US engineer at various plants

Plant codes (US)

• Plastylite (NJ): ear-shaped PR mark — the gold standard for early Blue Note
• Columbia plants: small letter codes (the plant locations were Pitman NJ, Terre Haute IN, Santa Maria CA) — code identifies which
• Capitol's Scranton, Jacksonville, Los Angeles plants — typically identified by small letter prefixes in the catalog number area
• Specialty Records Corp (SRC): an SRC mark or small logo. Common on 1970s-80s rock pressings

Plant codes (UK)

• Hayes (EMI's plant for Parlophone, HMV, Columbia UK) — usually indicated by EMI stampers and the GRAMOPHCO/BIEMRECORD coding system
• New Malden (Decca's plant) — Decca-coded matrices
• Phonodisc — Polydor and related labels

What to do with this

When you're inspecting a record at a shop or fair, scanning the deadwax for engineer and plant codes takes 30 seconds and can completely change your read on the pressing. An RVG mark on a Blue Note tells you it's at least cut from the right master. A PR ear mark tells you it was pressed at Plastylite (which is what makes it a true Lion-era original rather than a Liberty reissue). An RL etching on the right Led Zeppelin pressing turns a $50 record into a $500+ record.

These signals are also what the pressing variants pillar uses to distinguish originals from reissues — the engineer and plant codes are often the cleanest dividing line.

Every major label developed its own matrix conventions. Once you've internalized a label's pattern, you can identify their pressings at a glance. Here are the major labels you'll encounter:

Blue Note (Lion era, pre-1967)

Format: BLP/BST-####-A/B-CUT RVG (plus PR ear mark if pressed at Plastylite)

Example: BST-84163-A-2 RVG with a PR ear = Joe Henderson Inner Urge stereo, side A, second cut, mastered by Rudy Van Gelder, pressed at Plastylite. That's a Lion-era original.

Columbia (mono/stereo 1950s-60s)

Format: XLP-#####-A/B 1A (or similar) — the trailing letter+number identifies the mother/stamper

Example: XLP-44890-1A on a Miles Davis Kind of Blue (CL 1355 mono) side A would indicate first mother / first stamper

EMI / Parlophone (UK)

Format: catalog number + side letter + take number + stamper codes using the GRAMOPHCO or BIEMRECORD letter-coding

Example: YEX 637-1 G O on side A of Sgt. Pepper (UK PMC 7027) would indicate take 1, mother G (=1), stamper O (a number in their coding scheme)

Decca (UK, mono/stereo)

Format: ZAL-####-#W (mono) or ZAL-####-#W with -SKL prefix differences for stereo

RCA Victor (US)

Format: catalog-related number + take + W or B (cutting room marks)

1970s rock pressings

Format varies but often includes: catalog number, side identifier, take number, often plus the engineer signature (RL, STERLING, KENDUN, etc.)

What this means in practice

You don't need to memorize all label conventions — you'll learn the ones for the genres and eras you collect through repetition. The point is to recognize that matrix patterns are label-specific signatures. If you see a Blue Note album with a matrix that doesn't match the Blue Note pattern (no RVG, no Plastylite ear, weird formatting), it's almost certainly a later reissue or, in rare cases, a counterfeit.

For a deeper view of how matrix codes interact with mono/stereo variants — particularly relevant for early 1960s jazz where mono and stereo cuts often had very different matrix histories — see the mono vs stereo pressings guide.