Lesson 61 · All 12 keys

Quartal Chord Trainer

Learn how a Quartal chord ("So What" voicing) is built one semitone-count at a time — five notes stacked entirely in perfect 4ths, instead of the stacked 3rds every other chord in this app uses — then put it to work with three MIDI exercises: playing all 12 quartal chords around the circle of fourths, and 5 jazz plus 5 gospel chord progressions that show off its color, in every key.

How a Quartal chord ("So What" voicing) is built

A Quartal chord ("So What" voicing) — written quartal (e.g. Cquartal) — is a 5-note chord: five notes stacked entirely in perfect 4ths, instead of the stacked 3rds every other chord in this app uses. Every quartal chord — in any of the 12 keys — is built the exact same way, by counting semitones to the right from a root note:

  1. The starting note — this note names the chord.
  2. Count 5 semitones up from the root — a perfect 4th, the first "stack."
  3. Count 5 more semitones up (10 semitones from the root) — another perfect 4th stacked on top, landing on the ♭7th.
  4. Count 5 more semitones up (15 semitones from the root — an octave plus a minor 3rd) — another perfect 4th stacked on top.
  5. Count 4 more semitones up (19 semitones from the root — an octave plus a perfect 5th) — the top voice, closing out five notes built entirely from stacked perfect 4ths.
Example — Cquartal: start on C, count 5 semitones right to reach F, count 5 semitones more to reach B♭, count 5 semitones more to reach E♭, count 4 semitones more to reach G. C‑F‑B♭‑E♭‑G is the Cquartal chord.
Every other chord in this app is built by stacking 3rds; a quartal chord is built by stacking perfect 4ths instead — named for its famous use in Miles Davis’s "So What," and a modal-jazz and gospel-vamp staple ever since.

Try it: pick a root and build the chord step by step

Step 1 of 5
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Chord toneNoteSemitones from rootMIDI #

All 12 quartal chords at a glance

ChordRootStacked 4th (♭7th, oct.)Stacked 4th (♭3rd, oct. up)Stacked 4th (5th, oct. up)Stacked 4th (top voice)

This MIDI exercise plays all 12 quartal chords, one after another, moving around the circle of fourths — each chord's root sits a perfect 4th (5 semitones) above the last one: C → F → B♭ → E♭ → A♭ → D♭ → G♭/F♯ → B → E → A → D → G → back to C. Every chord is played as a full 5-note Quartal chord ("So What" voicing) (root, stacked 4th (♭7th, oct.), stacked 4th (♭3rd, oct. up), stacked 4th (5th, oct. up), stacked 4th (top voice) together).

Chord 1 of 12
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The 12 chords, in circle-of-fourths order

#ChordRootStacked 4th (♭7th, oct.)Stacked 4th (♭3rd, oct. up)Stacked 4th (5th, oct. up)Stacked 4th (top voice)

Five jazz chord progressions built around the Quartal chord ("So What" voicing). Pick a progression and play it in one key or cycle through all 12.

Key of C
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Progression in C

DegreeChordNotes

Five gospel chord progressions built around the Quartal chord ("So What" voicing). Pick a progression and play it in one key or cycle through all 12.

Key of C
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Progression in C

DegreeChordNotes