Key & harmony
Key lock
Key lock — master tempo on a CDJ — holds a track at its original pitch while you change its tempo. Without it, speeding a record up raises its key and quietly undoes whatever harmonic mixing you had planned.
Measured in our catalog
One semitone is a 5.95% tempo change, so a ±6% fader spans almost exactly one — and from 128 BPM that fader reaches 252,478 of 443,680 tracks with a detected tempo.
A semitone is also seven positions around the Camelot wheel, because each step of the wheel is a fifth. So running the fader to the end of its travel without key lock does not nudge the key — it throws it most of the way round the circle, which is why the setting exists at all.
5.95%
One semitone, in tempo
7
Camelot steps per semitone
121–135
A ±6% fader from 128
252,478
Tracks in that range
Measured on 11 August 2026 across the equal-tempered semitone ratio, against public tracks with a detected BPM for the reach figures.
Why it matters
It is the setting that makes key and tempo independent, and before it existed they were not. Pitch a record up to match a faster one and it arrives in a different key from the one the tag says, so a mix that looked correct on paper is not the mix you are playing.
It is not free. Every implementation is doing time-stretching in real time, and the further you push the fader the more the artefacts show — thin, glassy top end, smeared transients. Which is the argument for finding a record near your tempo rather than dragging one to it.
Frequently asked
Should key lock always be on?+
For harmonic mixing, yes — otherwise the key you are mixing is not the key on the tag. Some DJs turn it off for large tempo changes because the artefacts are more obvious than the key change.
How much does pitching change the key?+
A 5.95% tempo change is exactly one semitone, which moves you seven positions around the Camelot wheel. At 128 BPM that is a shift of about 7.6 BPM.
Does key lock affect sound quality?+
Yes, increasingly as you pitch further. It works by stretching audio in time, so small corrections are inaudible and large ones thin out the high end and blur the drums.
Related terms
Pitch fader
The pitch fader is the slider that speeds a track up or slows it down, usually by up to 6 or 8 percent. It is how two records are brought to the same tempo before they are mixed.
Camelot key
Camelot notation renames every musical key as a number from 1 to 12 plus a letter — A for minor, B for major. 8A is A minor. Codes next to each other on the wheel share most of their notes.
Harmonic mixing
Harmonic mixing means choosing the next track by key as well as tempo — staying on the same Camelot code, moving one step around the wheel, or swapping between the major and minor of the same number.
Beatmatching
Beatmatching is lining up two tracks so their beats land together — matching the tempo, then nudging the phase until the kicks coincide. It is the base skill every other mixing technique sits on top of.
Explore: Pitch and tempo calculator · The Camelot wheel · Browse by key · All DJ terms