Objectives

By the end of this chapter you will be able to:

Explain what a chord is and how it is built.
Build a major triad, a minor triad, and a 7th chord on the PO-33.
Write a 4-chord progression in the key of C major.
Recognise common chord progressions in popular music.

Musical concept: what is a chord?

A chord is three or more notes played at the same time. The most basic chord is a triad — three notes stacked in thirds. A major triad is built from the root, the major third, and the perfect fifth. A minor triad is built from the root, the minor third, and the perfect fifth.

In C major:

C major triad: C, E, G (pads 1, 5, 8).
C minor triad: C, D#, G (pads 1, 4, 8).

In C major:

F major triad: F, A, C (pads 6, 10, 13).
G major triad: G, B, D (pads 8, 12, 15).

The notes of the C major scale can be combined into 7 triads:

C major (pads 1, 5, 8).
D minor (pads 3, 6, 10).
E minor (pads 5, 8, 12).
F major (pads 6, 10, 13).
G major (pads 8, 12, 15).
A minor (pads 10, 13, 1 — but 1 is the next octave, so use pad 1 instead).
B diminished (pads 12, 15, 4 — but 4 is dissonant; skip).

Notice that three of the seven chords are major (C, F, G) and three are minor (D, E, A). The pattern is: in any major key, the I, IV, and V chords are major; the ii, iii, and vi chords are minor; the vii° chord is rare.

Sidebar — Roman numerals. Allen (Music Theory for Electronic Music Producers) uses Roman numerals to label chord progressions. The chord built on the first note of the scale (C in C major) is I. The chord built on the fourth note (F) is IV. The chord built on the fifth note (G) is V. So the progression I → IV → V is C → F → G. The progression vi → IV → I is Am → F → C. Roman numerals are universal: “I → V → vi → IV” is the same progression in every key.

The I-V-vi-IV progression

The most famous chord progression in modern pop is I → V → vi → IV. In C major, this is:

I = C major (pads 1, 5, 8).
V = G major (pads 8, 12, 15).
vi = A minor (pads 10, 13, 1).
IV = F major (pads 6, 10, 13).

Songs that use this progression: “Let It Be” (Beatles), “Someone Like You” (Adele), “No Woman No Cry” (Bob Marley), “Africa” (Toto), “Don’t Stop Believin’” (Journey), “Despacito” (Luis Fonsi), and over 1,000 other songs. It is the chord progression.

The PO-33 and chords

The PO-33 can play chords in a melodic slot by triggering three pads at the same time. But the PO-33 has only 4 voices of polyphony, so a 3-note chord uses 3 of those voices — leaving only 1 for the bass or the drums.

To write a chord progression:

Record a sustained melodic sound into slot 3 (a synth pad, a vocal “ahh”, a guitar chord).
Press WRITE, PLAY.
Step 1: press pads 1, 5, 8 simultaneously (C major chord).
Step 5: press pads 8, 12, 15 simultaneously (G major chord).
Step 9: press pads 10, 13, 1 simultaneously (A minor chord).
Step 13: press pads 6, 10, 13 simultaneously (F major chord).
Press WRITE to exit.

This is the I-V-vi-IV progression in C major. It will loop every 16 steps.

Sidebar — sustained notes. If your sample is short (1 second), the chord will cut off after 1 second. To make a chord last the whole 4 beats, your sample needs to be at least 0.5 seconds long. Longer is better — the chord will sustain across all 4 beats. Use a sustained sound (“ahhh”, a synth pad).

Voice management

The PO-33 has 4 voices. A typical track might use:

1 voice: kick drum (slot 9).
1 voice: snare drum (slot 10).
1 voice: hi-hat (slot 11).
1 voice: bassline (slot 2).

That’s 4 voices. Adding a chord progression uses 3 voices for the chord alone — too many.

Solutions:

Skip the hi-hat. The hi-hat is the most expendable voice. Replace it with a cymbal sample that plays only every 4 steps.
Use a one-note bassline. If the bassline plays only one note (the root), you can use it as part of the chord. The bass voice plays the root while the chord plays the third and fifth.
Drop the chord. The bassline + drums is enough for many songs. Add the chord only on certain steps.

In Part V we’ll learn pattern chaining, which gives you 8 voices of two patterns (16 voices of total polyphony across both). The PO-33 is not a multitrack DAW; you have to manage voices.

Guided exercise: the I-V-vi-IV progression

Success criteria: a 4-chord progression that cycles C → G → Am → F every 4 steps.

Record a sustained sound into slot 3 (sing “ahhh” and let it ring for 2 seconds).
Press WRITE, PLAY.
Step 1: press pads 1, 5, 8 (C major).
Step 5: press pads 8, 12, 15 (G major).
Step 9: press pads 10, 13, 1 (A minor).
Step 13: press pads 6, 10, 13 (F major).
Press WRITE to exit.

Listen to it loop. You should hear a clear chord progression that resolves into the F major chord at step 13. The chord returns to C on the next loop.

Creative challenge: the I-IV-V-I progression

The classic “three chords and a resolution”:

I = C major (pads 1, 5, 8).
IV = F major (pads 6, 10, 13).
V = G major (pads 8, 12, 15).
I = C major (pads 1, 5, 8).

Write this progression into steps 1, 5, 9, 13 of slot 3. Listen. This is the chord progression of “Twist and Shout”, “La Bamba”, and 80% of blues music.

Listening assignment

Listen to:

The Beatles, “Let It Be” (1970). I → V → vi → IV in C major. The same progression as the one we just wrote.
Adele, “Someone Like You” (2011). Same progression as “Let It Be”, but the melody uses notes from C minor. Same chords, different melody = different feel.
Journey, “Don’t Stop Believin’” (1981). I → V → vi → IV in E major. The same progression, transposed to a different key. The progression works in every key.
Toto, “Africa” (1982). The verse uses I → V → vi → IV. The chorus uses a different progression. The verse progression is the I-V-vi-IV we’re writing here.

Summary and checkpoint

Key takeaways:

A chord is three or more notes played at the same time. A triad is the most basic chord.
Major triads sound happy. Minor triads sound sad.
The I-V-vi-IV progression is the most famous in pop music. In C major: C-G-Am-F.
The PO-33 has only 4 voices. Manage them carefully.

Self-check:

[ ] Can you build a C major triad (pads 1, 5, 8)?
[ ] Can you write a I-V-vi-IV progression?
[ ] Do you understand why the same progression sounds happy in C major and sad in C minor?
[ ] Can you manage voices (skip the hi-hat if you have bass + chord + drums)?

If you answered “yes” to all four, you are ready for Part IV: groove and genre.

Part IV — Groove and Genre

Part III gave you the building blocks of melody and harmony. Part IV puts them into genre contexts — the specific combinations of BPM, swing, drum pattern, bassline, and chord progression that define a style of music. Each chapter is a different genre, a different feel, and a different recipe. By the end of Part IV you will have four complete beats in four different genres.