What Does Mixing in Key Mean?

Mixing in key means picking the next track so that its key is the same as, or harmonically related to, the key of the track already playing. When the two overlap, their melodies and bass lines agree instead of clashing, and the transition sounds like one piece of music.

Why key matters in a mix

Every melodic track is built on a scale. When two tracks in unrelated keys play at once, notes from one scale sit against notes outside the other's, and the result sounds sour even when the beats are locked. When the keys are the same or closely related, the overlap sounds intentional. The effect is strongest during long blends where bass lines and chords from both tracks are audible.

Which keys go together

Keys are related when they share most of their notes. The useful relationships for DJs are:

• The same key. Always safe.
• A fifth up or down. C major with G major or F major; A minor with E minor or D minor. One note differs between the scales.
• The relative major or minor. A minor and C major share every note.

Camelot and Open Key notation turn these relationships into neighbours on a wheel, so a DJ does not need music theory in the booth. On the Camelot wheel a track in 8A mixes with 7A, 9A and 8B.

How DJs do it in practice

1. Analyse the library so every track has a key, in whatever notation the software uses.
2. Sort or filter the browser by key when choosing the next track.
3. Prefer the same number or one step either way, or the other letter at the same number.
4. Use key lock if the tempo is being shifted, so the pitch, and therefore the key, does not move.

Energy, tempo and the crowd still come first. Key is a filter, not a rule.

When key does not matter

Drums carry no key. A DJ edit with a 16-bar drum intro and a 32-bar drum outro can be mixed into almost anything because, during the overlap, only percussion from one track is playing against the other. This is one reason DJs want edits with long clean edges. Vocals, pads and bass lines are where clashes happen.

How Club Ready Music helps

In the Studio you choose the key of a generated track from a Camelot list, and the panel shows which keys it mixes with. The finished MP3 carries the key three ways: the musical name such as Am in the standard key tag, the Camelot code such as 8A in an INITIALKEY text tag, and the Open Key code such as 1m in an OPENKEY text tag, so Serato, rekordbox, Traktor and VirtualDJ each find a notation they understand. The comment tag and the rekordbox XML repeat the key.

DJ edits of uploaded songs do not currently detect or shift key; they keep the song's original key and the pitch-preserving tempo shift keeps it that way.