Deck controls
Key sync
Key sync shifts a track’s pitch so its detected key matches another track’s, independently of tempo. It is not key lock: key lock preserves pitch while tempo changes, key sync deliberately changes pitch.
In practice
Key sync moves a record into key; key lock stops tempo moving it. They are opposite tools with similar names.
Keep shifts small — one semitone is safe on almost anything, two is usually fine on instrumentals, and beyond that vocals start to sound processed. Check the detected key before trusting the shift, because the whole operation is built on it. And use it as an occasional widener rather than a default: a set where every record has been moved into key is a set that has been processed, and the accumulated artefacts are audible even when no single shift is.
1
Semitone, safe on anything
2
Usually fine on instrumentals
Not key lock
The opposite tool
Where these come from: Standard pitch-shift tolerances in DJ use — practice, not catalog figures. The catalog reading of key distribution is on the key pages. For what we can measure, see what it is built on.
Why it matters
It turns harmonic mixing from a selection problem into a processing one. Instead of finding a record already in a compatible key, you take one that is not and move it — which widens what you can play next considerably, at a cost.
The cost is that pitch shifting is not free. A shift of one or two semitones is usually inaudible on percussion and clearly audible on vocals, and everything about the result depends on the detected key being right in the first place. A wrong key detection plus key sync gives you a confident shift to the wrong place.
Frequently asked
What is the difference between key sync and key lock?+
Key lock holds the pitch steady while you change tempo. Key sync deliberately changes the pitch to match another track. Similar names, opposite purposes.
How far can I shift a track?+
One semitone is safe almost anywhere, two is usually fine on instrumentals, and beyond that vocals start to sound obviously processed.
Should I use key sync all the time?+
No. It is best as an occasional widener. A set where everything has been shifted accumulates artefacts that are audible even when no individual shift is.
Related terms
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.
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.
Key detection
Key detection estimates a track’s musical key from the audio by measuring which pitches dominate and matching that profile against major and minor templates. It is an estimate, and it is confident even when wrong.
Pitch vs tempo
Tempo is how fast a track plays; pitch is how high it sounds. On a turntable they are one control, because speeding a record up raises its pitch. Digitally they can be separated, which is what key lock does.
Explore: Key transposer · Key lock · Harmonic mixing · All DJ terms