Create a Major Triad

In this tutorial, you'll build a major chord (triad) using just intonation ratios.

Objective

Create a three-note major chord where all notes play simultaneously.

Prerequisites

• Completed Build a Major Scale or equivalent experience
• Understanding of ratios for thirds and fifths

The Major Triad

A major triad consists of:

Note	Interval	Ratio	Decimal
Root	Unison	1/1	1.000
Third	Major third	5/4	1.250
Fifth	Perfect fifth	3/2	1.500

Step 1: Set Up the BaseNote

1. Open RMT Compose
2. Click the BaseNote (orange circle)
3. In the Variable Widget, scroll down to the bottom and click "Clean Slate" to remove all notes except the BaseNote
4. Verify the BaseNote settings are what you want:
   • frequency: e.g. 440 (A4)
   • tempo: e.g. 120 (120 BPM)

Step 2: Create the Root

1. With the BaseNote selected
2. In "Add Note / Silence" section, select "Note", then click "Create Note"
3. Select the new note
4. Set frequency:

base.f

Legacy JavaScript syntax

module.baseNote.getVariable('frequency')

5. Set duration to a whole note:

beat(base) * 4

Legacy JavaScript syntax

new Fraction(60).div(module.findTempo(module.baseNote)).mul(new Fraction(4))

6. Click Save

Step 3: Create the Third

1. With the root selected, click "Create Note" in "Add Note / Silence" (with "At Start" selected)
2. Select the new note
3. Set frequency (major third = 5/4):

base.f * (5/4)

Legacy JavaScript syntax

module.baseNote.getVariable('frequency').mul(new Fraction(5, 4))

4. Keep the same duration and start time
5. Click Save

Step 4: Create the Fifth

1. Select the root note again
2. Click "Create Note" in "Add Note / Silence" (with "At Start" selected)
3. Select the new note
4. Set frequency (perfect fifth = 3/2):

base.f * (3/2)

Legacy JavaScript syntax

module.baseNote.getVariable('frequency').mul(new Fraction(3, 2))

5. Click Save

Verification

1. Click Play
2. You should hear all three notes at once - a major chord!
3. The chord should sound bright and happy

Visual Check

In the workspace, all three notes should:

• Start at the same time (aligned vertically)
• Have different vertical positions (different frequencies)
• Be stacked: Root → Third → Fifth (bottom to top)

Understanding the Sound

The major triad sounds consonant because:

• 5/4 and 3/2 are simple ratios
• They align with the natural harmonic series
• The frequencies have many common overtones

Compare with 12-TET:

• TET major third = 2^(4/12) ≈ 1.26 (slightly sharp)
• Just major third = 5/4 = 1.25 (pure)

Exercises

Exercise 1: Minor Triad

Change the third from major (5/4) to minor (6/5):

base.f * (6/5)

Legacy JavaScript syntax

module.baseNote.getVariable('frequency').mul(new Fraction(6, 5))

The chord now sounds sad/dark!

Exercise 2: Add the Octave

1. Add a fourth note at the same time
2. Set frequency to 2/1:

base.f * 2

Legacy JavaScript syntax

module.baseNote.getVariable('frequency').mul(new Fraction(2))

This creates a fuller sound.

Exercise 3: Chord Inversion

Create a first inversion (third in the bass):

Note	Expression
Third (bass)	baseNote × 5/4
Fifth	baseNote × 3/2
Root (high)	baseNote × 2

Exercise 4: Chord Progression

Create a second chord that plays after the first:

1. Create a new root at startTime = firstChord.startTime + firstChord.duration
2. Build a chord on that root
3. You now have a two-chord progression!

Save Your Module

1. Menu > Save Module
2. Name it major-triad-just.json

Chord Reference

Other common chords in just intonation:

Chord	Ratios
Major	1/1, 5/4, 3/2
Minor	1/1, 6/5, 3/2
Diminished	1/1, 6/5, 36/25
Augmented	1/1, 5/4, 25/16
Major 7th	1/1, 5/4, 3/2, 15/8
Dominant 7th	1/1, 5/4, 3/2, 7/4
Minor 7th	1/1, 6/5, 3/2, 9/5

What You Learned

• Creating simultaneous notes using "At Start" positioning
• The ratios that make a major chord
• How to verify chord structure visually and aurally
• The difference between major and minor thirds

Next Steps

• Add Rhythm - Create rhythmic patterns
• Note Dependencies - Link chords together
• Explore the Chords category in the Module Bar