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What to do with BPM and key labels

Two numbers on a filename that most producers ignore. Using them properly is the difference between an hour of auditioning and five minutes.

Good packs write the tempo and key into every filename. Most producers scroll straight past both and audition by ear until something fits. That works, and it is the slowest possible method.

1.What the tempo actually tells you

Not just whether a sample fits your session. It tells you what your options are.

• Same tempo as your session. Drop it in, no processing, no artefacts. Ideal.
• Double or half your tempo. Also perfect, and the most underused fact in sampling. A phrase at 172 fits a session at 86 without any stretching whatsoever, because the bars line up exactly. Producers routinely reject samples for being too fast when they are simply at double time.
• Within a few percent. Stretch it. Modern algorithms handle three or four percent invisibly.
• Ten percent or more out. Now you are choosing. Stretch it and accept some smearing, or pitch it and accept that the key moves with it.

Which way you go often depends on where the material came from. Different eras of soul sit at very different tempos, and that is usually what decides whether a sample needs moving at all: 60s, 70s and 80s soul covers which decade lands where.

2.What the key tells you

• Whether two samples will sit together. Two phrases in the same key will layer. Two in unrelated keys will not, no matter how good both are. This is why layering attempts usually fail.
• Where to put your bass. The root note of the key is your bass note. That is the whole decision, made for you, in the filename.
• Which other samples are worth auditioning. Anything in the same key, or in the relative minor or major, is a candidate. Everything else is a longer job.

3.The relative minor, and why it matters

Every major key has a minor key that shares all the same notes, and vice versa. A sample in C major and a sample in A minor will sit together.

The pairs run three semitones apart: C major with A minor, G major with E minor, F major with D minor, and so on down the line. Learn the few you work in most and your usable library roughly doubles overnight.

4.A practical filing system

If your packs are labelled, you can sort and search rather than listen.

• Search by key when you have a project running. Working in F minor? Search your library for Fm and Ab. You have narrowed thousands of files to dozens without hearing a note.
• Search by tempo, including the double and half. Session at 90? Search 90, and 180, and 45. All three fit.
• Do not reorganise into folders by key. It sounds tidy and it breaks the moment a sample is useful in two contexts. Rely on search instead, which is exactly what the labels are for.

5.What to do when a pack is not labelled

Some are not. Two fixes.

1. Tempo. Your DAW will detect it. Check it over eight bars by ear, because detection is occasionally out by exactly double or half.
2. Key. A tuner plugin on the channel will tell you the root within a bar or two. Or play a bass note and move it until it stops clashing, which takes about fifteen seconds.

Treat a key reading from software as a starting point rather than an answer, because detection is unreliable on material that never settles on a home chord. There is more on why in soul chord progressions for beatmakers.

Then rename the file yourself, with the tempo and key in the name. Once.

Why a labelled library changes how you work

The real cost of an unlabelled library is not the auditioning. It is that you stop browsing, and end up using the same six samples because you know where they are and what they do.

A library you can search by tempo and key is one where you reach past the front of it. That is worth more than any individual sample in it.