Twelve notes. One ring.
Free music theory you can hear. Chords become shapes and keys become blocks, on the twelve notes of an octave.
C4 · 261.63 Hz ·
Twelve keys up, the same note.Twelve frets up, the same note.
Count twelve keys up from C, black and white together, and you land on C again. Same name, twice the frequency. So the twelve notes close into a circle.
Go twelve frets up the same string and you land on C again, at exactly half the string. Same name, twice the frequency. So the twelve notes close into a circle.
C4 261.63 Hz
Twelve equal steps.
Each step round the ring is one half-step. Every one multiplies the frequency by the same 1.0595, so twelve of them make exactly twice.
Tap any key on the ring to hear it.
A chord is a shape.
C, E and G make C major. Turn the triangle to any note and it stays a major chord. Flip it over and it turns minor: C and G stay, E drops to E♭.
From C to G is 7 half-steps. That distance is called a fifth.
Seven notes, almost evenly spread.
This is C major, the white keys. Its steps go 2, 2, 1, 2, 2, 2, 1. Each note now has a colour. Follow them round: they run smoothly, then break at E to F and at B to C, the two short steps.
Why these seven?
The lights go down.
The Half-Turn.
Same seven notes.
Six hold. Six turn half a turn.
Now each step round the ring is 7 half-steps. This is the circle of fifths.
One block. Slide it one notch.
In this order a key is seven neighbours in a row. Slide the block one notch and exactly one note changes.
C major
Every chord of the key sits inside the block.
On the turned ring a major chord is this shape and a minor chord is its mirror. Four of them make a loop: C, G, A minor, F.
Keep the ring open.
The same instrument, as three tools. Every one has the Order switch: half-steps or fifths.
Play something.
Play notes on the keys and the ring names the chord. If your browser supports it, a MIDI keyboard works too. Sing or hum one note and it lights the nearest one.
Play a few notes