What it is
Chords built by stacking fourths (or fifths) instead of thirds. Example from D: D G C F. They have no evident third: they sound open, modern, ambiguous between major and minor.
Diatonic quartal chords in C major
Stacking fourths with the notes of C: C F B (perfect fourth + augmented), D G C, E A D, F B E, G C F, A D G, B E A. Moving the same voicing by step (D G C → E A D → F B E) is the technique of diatonic planing in modal jazz.
The “So What” chord
Three perfect fourths plus a major third on top: E A D G B, over a D bass in D Dorian. Relative to the bass the notes are 9, 5, root, 11 and 13: the third (F) is missing, but the B (major 6th) says “Dorian.” Transposed to C Dorian: D G C F A over a C bass. It is a voicing that contains almost the whole mode.
Quintal
C G D A: stacked fifths, an epic sound, from soundtracks (Copland, film music, trailer pads). They are also the basis of the power chord with ninth.
Practical uses
- Quartal synth pads over a tonic pedal: a suspended atmosphere for hip hop and lo-fi.
- Modern guitar comping and fusion.
- Horn arranging: three trumpets in fourths give a “modern big band” sound.
- In K-pop and J-pop quartal voicings often appear in synth brass and in bridges.
Real example
“So What” by Miles Davis (Kind of Blue, 1959): Bill Evans's piano responses to the bass theme are precisely quartal voicings, which gave the chord its name.