SonodexWhat the key has to do with the mix
Two tracks playing at the same time sound clean when their notes fit together. If they do not, dissonance arises, especially in long crossfades with melodies, chords or basslines. In short, purely rhythmic transitions it is hardly noticeable.
There are twelve root notes, each in major and minor, so 24 keys. To compare them quickly, DJs use the Camelot wheel: it gives each key a number and a letter.
How to find the key
Programs detect the key automatically from the audio. This is usually reliable, but not infallible: tracks without a clear melody (pure drums, percussion) or with key changes give uncertain results. When in doubt, you listen or trust your ear.
The key is stored as metadata in the file or in the library and can therefore be filtered in any DJ program.
Key and tempo change
If you change the tempo with the pitch fader, the pitch also changes without “Key Lock”: roughly 6% faster corresponds to about a semitone higher. Then the measured key no longer matches what you hear.
In practice: getting the key into the library
Have the key detected once for the whole library and pick a notation you stick with: original (for example Am), Camelot (8A) or Open Key. Switching notation midway causes confusion, because some programs write it to different fields.
If two programs determine the same key differently, that is normal: with ambiguous tracks, the truth often lies between the relative key and the root. Decide by ear, and record your choice in the library.
Related terms
Frequently asked questions
Do I have to mix harmonically?
No. It is a tool for long, melodic transitions. Rhythmic mixes in techno often work without a matching key, too.
How do I know whether the key is right?
Play the track in the preview function together with a track in the detected neighbouring key. If it sounds clean, the value is right.