Key & harmony
Perfect fifth
A perfect fifth is the interval of seven semitones — the most consonant interval after the octave, and the one the Camelot wheel is built from. Moving one step round the wheel is moving a fifth.
In practice
Seven semitones, six shared notes out of seven. Every +1 and −1 on the wheel is this interval.
You never need to name it in a booth, but it is worth knowing when the wheel stops being enough. If a record is unlabelled, or a detector has clearly got it wrong, the question "does the bassline of this one agree with the pads of that one" is the same question the fifth answers — and your ear can answer it directly. Twelve fifths return to the start, which is why the wheel closes and why any key is reachable from any other in at most six moves.
7
Semitones in a fifth
6 of 7
Notes two fifth-apart keys share
12
Fifths back to the start
Where these come from: Interval arithmetic and the construction of the Camelot wheel. The measured behaviour of the wheel moves in real sets is on the harmonic mixing page. For what we can measure, see the wheel this builds.
Why it matters
It is the reason the wheel works at all, and knowing it turns a lookup into an understanding. Two keys a fifth apart share six of their seven notes, so almost nothing in one disagrees with anything in the other — which is why the +1 and −1 moves are safe and why they are the two moves every DJ makes most.
It also explains why the wheel is a circle rather than a line. Keep moving by fifths and after twelve steps you arrive back where you started, which is exactly the twelve numbers on the wheel. The Camelot system is that sequence with the theory removed.
Frequently asked
Why is the Camelot wheel arranged in fifths?+
Because keys a fifth apart share six of seven notes, so neighbouring numbers are the safest moves. The wheel is the circle of fifths with the theory relabelled as numbers.
What makes a fifth "perfect"?+
It is a naming convention for intervals that are neither major nor minor — the unison, fourth, fifth and octave. It reflects their simple frequency ratios rather than any judgement of quality.
Do I need to know intervals to mix in key?+
No. The wheel exists so you do not. Knowing them helps when the label is missing or wrong, which is the situation the wheel cannot help with.
Related terms
Circle of fifths
The circle of fifths arranges the twelve keys so that neighbours are a fifth apart and share almost all their notes. The Camelot wheel is this diagram with the keys relabelled as numbers and letters.
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.
Parallel key
A parallel key shares its root note but swaps major for minor: A major and A minor. It is not the same as a relative key, which shares the notes but not the root.
Enharmonic
Two notes are enharmonic when they sound identical and are written differently — C sharp and D flat are the same pitch with two names. It is a notation difference, not a musical one.
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