1.5 Basic Triads
Three-note chords: the foundation of Western musical harmony
Key Concepts
- Triad: A chord consisting of three notes stacked in thirds
- Components: Root, Third, Fifth
- 4 Types: Major, Minor, Diminished, Augmented
- Pattern Scale: The major scale generates 3 major, 3 minor and 1 diminished
- Inversions: 3 positions (basic + 2 inversions)
- Progressions: Sequences of chords that create harmonic movement
What is a Triad?
Definition
A triad is a chord consisting of three notes stacked in thirds. It is the simplest and most fundamental chord in Western tonal music. The name derives from the Greek ‘trias’ (three), referring precisely to the three notes that make it up.
Structure of a Triad
Each triad consists of three essential elements, each with a specific role:
1⃣ Fundamental (Root)
The root note of the chord – the one that gives it its name. It is the harmonic centre. In C major, the root note is C.
2⃣ Third
The interval of a third from the root. It determines the nature of the chord: a major third = a major chord; a minor third = a minor chord.
3⃣ Fifth
A note a fifth above the root (or a third above the third). It completes the sound of the chord, adding fullness and stability.
C major triad: C (root) – E (major third) – G (perfect fifth)
Historical Background
Triadas as we know them today emerged gradually during the Renaissance (15th–16th centuries). Before that, medieval music mainly used fourths and fifths (organum). Terts were considered dissonant! It was only with composers such as Josquin des Prez and Palestrina that triads became the basis of harmony. During the Baroque period (1600–1750), with Monteverdi and Bach, the tonal harmonic system based on triads became fully established.
The Four Types of Triads
Classification by Intervals
There are four types of triads, determined by the interval of the third and the fifth in relation to the root. Each type has a distinctive sound and a specific musical application.
Major Triad
Major third + perfect
fifth. A bright, steady, joyful sound. It is the most ‘harmonious’ and positive triad.
C major (Do maggiore)
Formula:
Root note + 4 semitones + 3 semitones
(4 semitones = major third, then +3 = perfect fifth)
Examples of major triads:
- C = C - E - G
- G = G - B - D
- F = F - A - C
- D = D - F♯ - A
Famous Songs:
- "Let It Be" – The Beatles (C major)
- "Sweet Home Alabama" – Lynyrd Skynyrd
- "Three Little Birds" – Bob Marley
Minor Triad (Minor)
Minor third + Perfect
fifth. A dark, melancholic, introspective sound. It conveys sadness or emotional depth.
A minor (A minor)
Formula:
Root note + 3 semitones + 4 semitones
(3 semitones = minor third, then +4 = perfect fifth)
Examples of minor triads:
- Am = A – C – E
- Dm = D – F – A
- Em = E – G – B
- Bm = B – D – F♯
Famous Songs:
- "Stairway to Heaven" – Led Zeppelin (Am)
- "Losing My Religion" – R.E.M.
- "Mad World" – Tears for Fears
Diminished Triad
Minor third + diminished
fifth. A tense, unstable, dissonant sound. Requires resolution to a consonant chord.
B° (diminished B)
Formula:
Root note + 3 semitones + 3 semitones
(Two overlapping minor thirds = a tritone between the root and the fifth)
Examples of diminished triads:
- B° = B - D - F
- F♯° = F♯ - A - C
- C♯° = C♯ - E - G
Usage:
It is frequently used as a passing chord between two stable chords. The seventh degree of every major scale is diminished (e.g. B♭ in C major).
Augmented Triad
Major third + augmented
fifth. An ambiguous, suspended, mysterious sound. It creates tension without a clear direction.
C+ (C sharp)
Formula:
Root note + 4 semitones + 4 semitones
(Two overlapping major thirds = symmetrical)
Examples of augmented triads:
- C+ = C - E - G♯
- F+ = F - A - C♯
- G+ = G - B - D♯
Usage:
Rare in pop/rock music, but more common in jazz and impressionist music (Debussy). It has some interesting symmetrical properties: any note can be the root note!
Quick Comparison (from C)
| Type | Notes | Intervals | Semitones | Sound |
|---|---|---|---|---|
| Major (C) | C - E - G | M3 + m3 | 4 + 3 | Bright |
| Minore (cm) | C - E♭ - G | m3 + M3 | 3 + 4 | Dark |
| Decrease (°C) | C - E♭ - G♭ | m3 + m3 | 3 + 3 | Teso |
| Increased (C+) | C - E - G♯ | M3 + M3 | 4 + 4 | Ambiguous |
How to Build Any Triad
Three Construction Methods
Method 1: From La Scala
Take a note from the scale and stack the thirds (skip a note, take the next one).
Example: Constructing D major (D) from the D major scale
- D major scale: D – E – F♯ – G – A – B – C♯ – D
- Essential: D (Level 1)
- Third: skip E, play F♯ (3rd degree)
- Fifth: skip G, take A (5th degree)
Result: D – F♯ – A (D major triad)
Method 2: Counting Semitones
Use the semitone formula for each type of triad.
Example: Playing E minor (Em)
- Essential: E
- E + 3 semitones (minor third) = G
- G + 4 semitones (another third) = B
Result: E – G – B (E minor triad)
Method 3: By Intervals from the Fundamental
Calculate the third and fifth as intervals from the root.
Example: Constructing G major (G)
- Essential: G
- Major third from G (4 semitones) = B
- Perfect fifth from G (7 semitones) = D
Result: G – B – D (G major triad)
Harmonisation of the Major Scale
The Universal Pattern
When we build triads on each degree of a major scale, we always get the same pattern of major, minor and diminished chords. This pattern is universal and applies to all 12 major scales.
Example: C Major scale
| Grado | Name | Agreement | Notes | Type | Symbol |
|---|---|---|---|---|---|
| I | Tonic | Do | C - E - G | Major | C |
| ii | Supratonic | D minor | D - F - A | minor | Dm |
| iii | By means of | E flat minor | E - G - B | minor | Em |
| IV | Subdominant | It | F - A - C | Major | F |
| V | Dominant | Sol | G - B - D | Major | G |
| vi | Supra-dominant | The minor | A - C - E | minor | Am |
| vii | Sensitive | It has decreased | B - D - F | decreased | B° |
Universal Pattern
In ALL major scales, the triad pattern is always:
I – ii – iii – IV – V – vi – vii°
(Upper case = major, lower case = minor, ° = diminished)
In Other Shades
G Major:
G – Am – Bm – C – D – Em – F♯°
D Major:
D – Em – F♯m – G – A – Bm – C♯°
F major:
F – Gm – Am – B♭ – C – Dm – E°
In Maggiore:
A – Bm – C♯m – D – E – F♯m – G♯°
The Triads’ Inversion
What are Inversions?
An inversion is created by moving the lowest note of a triad up an octave. This changes the bass note of the chord but not the notes that make it up. Every triad has three inversions: the root position and two inversions.
Ground State
The fundamental is the lowest
note (fundamental position)
C / E / G
(1 - 3 - 5)
Grade: C
Primo Inversion
The third is the lowest
note (the root is above it)
E / G / C
(3 - 5 - 1)
Grade: C/E
According to Inversion
E is the lowest
note (the root and the third above it)
G / C / E
(5 - 1 - 3)
Notation: C/G
Why Use Inversions?
- Voice leading: Creating more melodic and fluid bass lines
- Varying the sound: Same chord, slightly different tone
- Avoid sudden changes: Move more gradually between chords (especially on the piano)
- Bass line: The bass can follow a melody or provide an independent counterpoint
Notation of the Inversions
The ‘slash’ notation is used: the name of the chord followed by ‘/’ and the bass note.
- C = C major in root position (C in the bass)
- C/E = C major, first inversion (E in the bass)
- C/G = C major, second inversion (G in the bass)
- Am/C = A minor, first inversion (C in the bass)
Harmonic Progressions
What Are Progressions?
A harmonic progression is a sequence of chords that creates musical movement and direction. Progressions are the ‘driving force’ that propels the music forward, creating tension and resolution.
V → I (Perfect Cadence)
The strongest and most decisive progression. It creates a sense of definitive conclusion.
G → C
Why does it work?
The V (dominant) contains the sub-dominant (B), which resolves to the tonic (C), creating a strong magnetic pull towards the I chord.
Songs: Used at the end of almost all classical and pop tracks
I → vi → IV → V (Pop/Rock)
One of the most commonly used chord progressions in pop and rock music of all time.
C → Am → F → G
Famous songs:
- "Let It Be" – The Beatles
- "No Woman No Cry" – Bob Marley
- "With or Without You" – U2
- "Don't Stop Believin'" – Journey
IV → I (Plagal cadence)
Known as the ‘Amen cadence’. A gentler, more relaxed conclusion.
F → C
Commonly found in sacred music, gospel and spirituals. It has a softer sound than the perfect cadence, and is less ‘urgent’.
Example: The closing ‘Amen’ in religious hymns
I → IV → V (Blues/Rock)
The foundation of the blues and rock and roll. Simple yet incredibly powerful.
C → F → G
Famous songs:
- "La Bamba" – Ritchie Valens
- "Twist and Shout" – The Beatles
- "Wild Thing" – The Troggs
- 12-bar blues (standard)
Other Common Progressions
- I → V → vi → IV (C-G-Am-F): “Axis of Awesome” – thousands of pop hits
- ii → V → I (Dm-G-C): A fundamental element in jazz, the ‘turnaround’
- I → IV → I (C-F-C): Folk, country, simple music
- vi → IV → I → V (Am-F-C-G): A widely used pop variation
- I → vi → ii → V (C-Am-Dm-G): ‘Circle progression’, 1950s–1960s
- I → iii → IV → V (C-Em-F-G): Doo-wop, oldies
Study Tips
Recommended Exercises
- Play all 4 types of triads from each note (12 × 4 = 48 chords)
- Practise harmonisation: build the seven triads of each major scale
- Play the inversions of each triad (3 positions per chord)
- Practise the standard scales in all keys
- Analyse the chord progressions of your favourite songs
- Write triads on a staff to memorise the notes
Common Mistakes to Avoid
- Confusing major and minor (always check the third!)
- Not understanding the difference between ‘diminished’ and ‘minor’ (the fifth!)
- Memorising chords without understanding how they are constructed
- Ignoring inversions (they’re essential for voice leading!)
- Do not practise scales in every key
- Studying theory alone without playing the chords on your instrument
Recommended Course of Study
- Weeks 1–2: Learn major and minor scales. Practise C, G, D, Am, Em and Dm
- Weeks 3–4: All 12 major and 12 minor scales. Memorise the formulas (4+3, 3+4)
- Weeks 5–6: Scale harmonisation. I–ii–iii–IV–V–vi–vii° pattern
- Weeks 7–8: Inversions. Practise the three positions of each chord
- Weeks 9–10: Decreases and increases. Less common but important
- Week 11+: Progressions. V–I, I–vi–IV–V, I–IV–V in all keys
Summary
Triads are chords consisting of three notes (root, third, fifth) which form the basis of tonal harmony. There are four types: major (bright), minor (dark), diminished (tense) and augmented (ambiguous). Every major scale produces a universal pattern of seven triads: I–ii–iii–IV–V–vi–vii°.
Inversions allow you to vary the bass whilst retaining the same notes, which are essential for smooth voice leading. Harmonic progressions (sequences of chords) create movement and musical direction. Progressions such as V–I, I–vi–IV–V and I–IV–V form the basis of countless songs across all musical genres.
Next Steps
Congratulations! You have completed Level 1 – Fundamentals!
You now know the basics of musical notation, rhythm, intervals, scales and triads. You’re ready for the intermediate level:
- Modes (2.1) – The 7 modal scales derived from the major scale
- Seventh Chords (2.2) – Expanding triads with a fourth note
- Theory Index – Back to the full list of lessons
Remember: Triads are everywhere in music. Even the most complex chords (seventh, ninth, eleventh) are built from triads. Make sure you’ve fully mastered this level before moving on!