Groove pitch controls how tightly the grooves sit together on a lathe cut record — and it determines the trade-off between playing time, volume and bass response. Here's how it works.
Every record — pressed or lathe cut — is a continuous spiral groove cut into the disc from the outside edge to the label area. Groove pitch is how close together the individual revolutions of that spiral sit. Pack them tightly and you get more grooves on the disc, meaning longer playing time. Space them further apart and each groove has more room — room that translates directly into volume and bass headroom.
Groove pitch is measured in LPI: Lines Per Inch. One LPI means one groove revolution per inch of the record's radius. A typical 12" record runs somewhere between 90 LPI for loud, bass-heavy club music and 300+ LPI for longer, quieter material. Most lathe cut services operate in the 90–200 LPI range depending on the content and format.
The relationship between pitch, playing time and audio quality is the central technical constraint of the format — and it applies to every record, whether it was cut in 1975 or this afternoon on a VinylRecorder.
There are two ways a cutting lathe can manage groove pitch — and they produce meaningfully different results, especially on longer or more dynamic material.
The groove spacing stays constant from the first revolution to the last. Whether the audio is a loud kick drum or 10 seconds of near-silence, every groove is the same distance from its neighbour.
This makes the cutting process simpler and more predictable. You set a pitch before cutting — say, 130 LPI — and the lathe holds that figure throughout the side. The playing time and available groove width are determined at the start and don't change.
The limitation: quiet passages don't need wide grooves, but they get them anyway. That wasted space could have been used to add more music, or given back to the louder sections. With fixed pitch, you're optimising for the worst case.
The lathe reads the audio signal and adjusts groove spacing dynamically — widening during loud passages and tightening during quieter ones. The cutting system anticipates the signal (usually looking a second or two ahead) and pre-adjusts the pitch before the loud moment arrives.
This is how commercial pressing plants have always worked. It allows significantly more audio to fit onto a disc at comparable quality — or alternatively, better quality for the same playing time. A well-implemented variable pitch system on a 12" can add several minutes of playing time per side compared to fixed pitch at the same volume.
The trade-off: more complex setup, more variables to manage, and the lookahead system needs to be calibrated correctly to avoid groove collisions — where adjacent grooves physically overlap and damage the stylus or disc.
In practice for lathe cutting: most lathe cut services — including Diz — use fixed pitch cutting. Variable pitch requires dedicated pitch-control hardware or software tightly integrated with the cutting chain. Fixed pitch at a sensibly chosen LPI gives consistent, predictable results and is well-suited to the short run and one-off nature of lathe cutting. The playing time limits are real, but they're predictable and manageable if you master your material correctly.
The table below gives practical playing time estimates by format and LPI setting. These assume material mastered at a sensible level for vinyl — not maximised for streaming. Loud masters with heavy bass will need more conservative settings (lower LPI) to avoid groove distortion.
| Format | Speed | LPI | Approx. playing time / side | Bass headroom |
|---|---|---|---|---|
| 7" | 45rpm | 90–110 | 3–4 min | Full — ideal for loud, bass-heavy cuts |
| 7" | 45rpm | 130–160 | 4–6 min | Good — still handles bass well with solid mastering |
| 7" | 45rpm | 180–220 | 6–8 min | Reduced — mid-heavy content only, bass must be modest |
| 10" | 45rpm | 90–120 | 6–8 min | Full |
| 10" | 33rpm | 120–160 | 10–14 min | Good |
| 12" | 45rpm | 90–110 | 8–10 min | Full — the classic club cut format |
| 12" | 33rpm | 120–160 | 15–20 min | Good with careful mastering |
| 12" | 33rpm | 180–260 | 20–28 min | Reduced — suitable for voice-led or acoustic material |
These are approximate ranges. The actual achievable time depends heavily on the dynamic range of the master, the low-frequency content, and the cutting level. A heavily compressed techno track and an acoustic folk record can be cut at the same LPI with completely different outcomes — the techno will require a more conservative pitch, the folk record will have more room to play with.
Bass is the biggest constraint in vinyl cutting. A sub-bass hit at 40 Hz requires the stylus to move a large lateral distance every 25 milliseconds — which needs a wide groove. The lower the frequency and the louder the level, the wider the groove needs to be. Pack the grooves too tightly and a loud bass hit will cause the stylus to physically jump into the adjacent groove — a groove collision, resulting in a loud crack and potentially damage to the stylus or disc.
The standard approach is to high-pass filter below 30 Hz and apply an elliptical (mono) filter to bass frequencies below around 150–200 Hz before cutting. This ensures bass information is mono in the groove (lateral only, no vertical component), reducing the excursion required without affecting the perceived low end on playback through a well-set-up system.
As the stylus travels toward the centre of the disc, the linear velocity drops — the groove is moving past the stylus more slowly for the same LPI. This means less time between cycles of a given frequency, which limits the stylus's ability to accurately trace high-frequency content. This is why the inner grooves of a record always sound marginally worse than the outer grooves — it's physics, not poor mastering.
Practically: if you have material with significant high-frequency content (cymbals, high hats, bright synths, sibilant vocals), it's better placed at the beginning of a side than the end. Long sides make this more pronounced.
At 45rpm, the groove moves past the stylus faster than at 33rpm for any given radius. This means better high-frequency reproduction, less inner groove degradation, and more headroom for dynamic content — at the cost of playing time. A 7" 45rpm single is the format with the best audio quality per minute of material on a lathe cut record. If sound quality is the priority and playing time is flexible, 45rpm is the right choice.
When you place an order, you'll be asked for your track length and format. The LPI is set based on this — and on the character of the material if you tell us. A 4-minute 7" at 45rpm gets plenty of groove space and can handle whatever your master throws at it. A 7-minute 7" at 45rpm needs more modest low end and dynamics. If your material sits in between, describe it and the cut will be optimised accordingly.
People sometimes arrive at lathe cutting expecting a full LP-side per format — 22 minutes on a 12", 8 minutes on a 7". These numbers are achievable, but they come with caveats that matter if you care about sound quality.
Long sides require quiet masters. You can push 20+ minutes onto a 12" at 33rpm, but the LPI required means tight grooves, reduced bass headroom, and roll-off in the upper frequencies toward the end of the side. This works for speech, acoustic music, or carefully mastered ambient material. It doesn't work for techno at 0 dBFS.
Bass-heavy music has a hard ceiling. Dub, drum and bass, grime, club techno — anything with significant sub-bass energy — needs generous groove spacing to translate properly. For this material, 5–6 minutes per 7" side or 10–12 minutes per 12" side at 33rpm is a realistic target for a cut that sounds right on a decent system. Push past that and you're trading sound quality for playing time.
The sweet spot is shorter, louder, and punchier. The format that plays to a lathe cut's strengths is a 7" 45rpm single: 3–4 minutes of well-mastered music with proper headroom. This is the format with the best signal-to-noise ratio, the widest grooves relative to playing time, and the most consistent results from the inner to the outer groove.
None of this is a reason to avoid longer formats — it's just useful context before you approach mastering. Know your format, know your LPI, and prepare the master accordingly. If you send files and you're not sure, say so — the cut can be assessed and you'll get advice before anything is committed to disc.
If this raised more questions about how lathe cut vinyl works, these pages cover the rest of the technical ground.
The full overview — how a lathe cut record is made, how it sounds, and how it compares to a pressed record.
Read the guide →When to cut, when to press — a practical comparison of both formats by cost, quality, turnaround and use case.
Read the comparison →