Why changing tempo changes the key
Think of a cassette or a turntable: spin faster and voices go up, spin slower and they go down. Playing digital audio faster works the same way, every frequency gets multiplied by the same amount.
The numbers worth remembering:
- About 6% faster is about a half step higher.
- About 12% faster is nearly a whole step higher.
On the Camelot wheel, a half step up is a jump of 7: an 8A track becomes 3A, and no longer fits the 8A tracks you picked. See what the Camelot wheel is.
What key lock does
Key lock, also called Master Tempo, uses time-stretching: it lengthens or shortens the sound while keeping the pitch. Faster or slower, the key stays where it is.
When to turn it on
- Harmonic mixing with tracks more than a few percent apart in tempo. Without it, the keys you picked so carefully drift away.
- Tracks with vocals. Raised voices sound fake, especially female vocals.
- Previewing a track at your set's tempo before you play it.
When to consider turning it off
- Big tempo changes, above roughly 10–15%. Time-stretching starts to leave artifacts: warbling, a smeared kick, crunchy hi-hats.
- When you want the pitch to move, like speeding up for a higher, brighter vocal or slowing down for weight.
- Tiny adjustments of 1–2%. The key barely moves, so leave it off for the purest sound.
With TaxonomyDJ
The TaxonomyDJ player changes tempo from 0.5× to 2×, or straight to a target BPM with Speed ▸ By BPM, and always keeps the key, like Master Tempo. You hear a new track at your set's tempo before you decide to play it. Free on every plan.
No BPM for your library yet? Read how to find the BPM of a song.