Build a Major Scale

In this tutorial, you'll build a major scale using just intonation ratios - the exact fractions from the natural harmonic series.

Objective

Create an 8-note major scale (Do-Re-Mi-Fa-Sol-La-Ti-Do) using pure ratios.

Prerequisites

• RMT Compose running
• Familiarity with the Variable Widget
• Understanding of Core Concepts

The Major Scale Ratios

Degree	Name	Ratio	Decimal
1	Do	1/1	1.000
2	Re	9/8	1.125
3	Mi	5/4	1.250
4	Fa	4/3	1.333
5	Sol	3/2	1.500
6	La	5/3	1.667
7	Ti	15/8	1.875
8	Do	2/1	2.000

Step 1: Start Fresh

1. Open RMT Compose
2. Click Menu (☰) > Load Module > Reset to Default Module
3. Or load the "octave" interval module as a starting point

Step 2: Set Up the BaseNote

1. Click the BaseNote (orange circle)
2. In the Variable Widget, verify:
   • frequency: new Fraction(440) (A4, but any frequency works)
   • tempo: new Fraction(120) (120 BPM)

Step 3: Create the Root (Do)

1. Click the BaseNote
2. Click "Add Note" > "Add at Start+Duration"
3. Select the new note
4. Set its frequency:

module.baseNote.getVariable('frequency')

5. Set its duration to a quarter note:

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

6. Click Save

Step 4: Create Re (9/8)

1. Select the Do note you just created (Note 1)
2. Click "Add Note" > "Add at Start+Duration"
3. Select the new note (Note 2)
4. Set its frequency:

module.baseNote.getVariable('frequency').mul(new Fraction(9, 8))

5. Click Save

Step 5: Create Mi (5/4)

1. Select Note 2
2. Click "Add Note" > "Add at Start+Duration"
3. Select Note 3
4. Set its frequency:

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

5. Click Save

Step 6: Create Fa (4/3)

1. Select Note 3
2. Add a new note
3. Set frequency:

module.baseNote.getVariable('frequency').mul(new Fraction(4, 3))

Step 7: Create Sol (3/2)

1. Add note after Fa
2. Set frequency:

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

Step 8: Create La (5/3)

1. Add note after Sol
2. Set frequency:

module.baseNote.getVariable('frequency').mul(new Fraction(5, 3))

Step 9: Create Ti (15/8)

1. Add note after La
2. Set frequency:

module.baseNote.getVariable('frequency').mul(new Fraction(15, 8))

Step 10: Create High Do (2/1)

1. Add note after Ti
2. Set frequency:

module.baseNote.getVariable('frequency').mul(new Fraction(2, 1))

Or simply:

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

Verification

1. Click Play to hear your scale
2. You should hear 8 notes ascending
3. The last note (high Do) should sound like the first note, but higher

Check Your Work

Select each note and verify the frequency ratio in the Variable Widget:

Note ID	Expected Ratio
1	1/1
2	9/8
3	5/4
4	4/3
5	3/2
6	5/3
7	15/8
8	2/1

Save Your Module

1. Click Menu > Save Module
2. Rename to major-scale-just.json

Exercises

Exercise 1: Descending Scale

Modify your scale to descend from high Do to low Do.

Hint: Change the order of start times, or create new notes in reverse order.

Exercise 2: Change the Root

1. Click the BaseNote
2. Change frequency to new Fraction(330) (E4)
3. Play - the scale is now in E major!

Exercise 3: Longer Notes

Change all durations to half notes:

new Fraction(60).div(module.findTempo(module.baseNote)).mul(new Fraction(2))

What You Learned

• Major scale intervals as pure ratios
• Creating sequential notes using "Add at Start+Duration"
• How changing BaseNote transposes the entire scale
• The relationship between tempo and duration

Next Steps

• Create a Major Triad - Build a chord
• Add Rhythm - Create varied rhythms
• Compare with 12-TET to hear the difference