The four triad qualities · From Zero to Mozart

A triad is two thirds stacked. But a third can be major (4 half steps) or minor (3), and the two choices give you four kinds of triad — four different colours.

Quality	Lower 3rd	Upper 3rd	Root → 5th	Sound
Major	major	minor	perfect 5th	bright, settled
Minor	minor	major	perfect 5th	dark, settled
Diminished	minor	minor	diminished 5th	tense, unstable (it contains a tritone)
Augmented	major	major	augmented 5th	floating, no gravity

Hear all four on one root

Built on D, played as broken chords (root, 3rd, 5th):

72 bpm

D major, D minor, D diminished, D augmented — same root, four flavours. Major and minor differ by one note (the 3rd). Diminished pulls the 5th in too; augmented pushes it out. Play the four bars and listen: the last two won't sit still.

Major and minor rolled

The two "settled" triads are playable as a rolled chord on the violin — here's G major and G minor, open G and open D with the 3rd on the A string:

56 bpm

G major, then G minor — rolled bottom to top. The only note that moves is the 3rd on the A string, a half step. That half step is the difference between bright and dark.

Try it

Try

Play D and A (open D string, open A string) together as a drone-ish double stop. Now add F♯ (high 2 on the D string) in your ear — D major. Slide it back to F natural — D minor. You're hearing the 3rd flip the chord's whole character while the outer two notes hold still.

Triad qualities

The usual mistake

Hearing a diminished or augmented triad and assuming someone played a wrong note. They're meant to sound unsettled — that's their job. A diminished triad usually appears on the way to the tonic (it's built on the leading tone); an augmented one is a colour a composer reaches for deliberately.