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The problem it solves
The major triad is the most basic chord of tonal music and the basis of degrees I, IV and V; being able to build it and recognise it opens the door to harmony.
Detailed theory
Key idea
It stacks in thirds: a major third below and a minor third above.
Between the root and the fifth there is a perfect fifth, very consonant and stable.
Understand it
Start from a base note, the root. Add the note a major third (four semitones) above it: that is the third of the chord. On top of that put a minor third (three semitones) more: that is the fifth.
In C: C (root), E (major third above C) and G (minor third above E). From C to G there is a perfect fifth, of seven semitones, the interval that gives the chord its solidity.
The order of the thirds is what defines the quality: major below and minor above makes a major triad. Swap the order and you get a minor triad.
It sounds so stable for a physical reason: the octave (2:1), the perfect fifth (3:2) and the major third (5:4) are among the first harmonics of the natural series, and the ear processes them as consonant.
An analogy: building the triad is like stacking blocks skipping one each time (1 → 3 → 5). A major third below and a minor one above fit into a stable tower: the major triad.
Chord progression
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La diferència entre major i menor és NOMÉS la tercera: baixa el E a Eb i la tríada major (C-E-G) es torna menor (C-Eb-G).
How to recognise it
How it's written
It is written by stacking 1-3-5 on the root, for example C-E-G. In American chord symbols, a major triad is notated with just the letter of the root: C means C major.
How it feels
It sounds stable, open and full-bodied: a firm, resolved base. It does not necessarily mean happy; the same triad can sound bright or solemn depending on the context.
Common mistake
Playing the three notes as a block without knowing which is the root, the third and the fifth.
Confusing the major triad with the minor one: the only difference is the third, a semitone higher or lower.
Try it
Play C-E-G first as an arpeggio, one note after another, and then as a chord, all at once.
Lower the third (E) a semitone to Eb: you have just turned the major triad into a minor one (C-Eb-G).
On the instrument
Stacked triad
C major: a major third from C to E (4 semitones) and a minor third from E to G (3 semitones), with a perfect fifth between C and G.
Where it's used
- Accompanying
- Playing the tonic or dominant chord of a song.
- Recognising chords
- Telling a major triad from a minor one by ear.
- Accompanying melodies with coherent chords.
- Recognising chord qualities in real songs.
Examples
Chord progression
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La mateixa estructura major (1-3-5) en tres tonalitats: canvia la fonamental, però el so brillant i estable es manté.
Exercises
Play major triads — basic
Play the major triad shown, with simple roots (C, G, F).
Complete 5 attempts · 70% accuracy to pass
Play major triads — intermediate
Play the major triad shown, now with more roots (includes Bb).
Complete 8 attempts · 70% accuracy to pass
Play major triads — advanced
Play the major triad shown from any of the 12 roots, including notes with accidentals.
Complete 10 attempts · 70% accuracy to pass
Mini test
Check that you've got it.
0/8 answeredQuestion 1/8
Which three notes make up a major triad?