Voicing Box I · P4 + m2 + M3

Box I

The foundational rootless shape: a perfect fourth at the bottom, a half step in the middle, and a third on top. Each four-note shape voices six different chord qualities depending on which root you imagine underneath.

Voicing Boxes Series

Overview·Box I·Box II·Box III·Box IV·Box V·ii-V-I (I)·ii-V-I (II)

What this box is

Box I is a four-note rootless shape. Its interval signature from the bottom up is P4 + m2 + M3 (5 + 1 + 4 semitones). The shape itself doesn't change — only the chord you imagine underneath does. That's how a single fingering can voice 6 distinct chord qualities.

Six chord qualities

Each cell of Box I maps to these six qualities:

m77sus7♯9Δ♯5m7♭56/9

Cells

tap a cell to inspect its shape

Voicing

B – E – F – A

Stack from low to high — P4 + m2 + M3

Six chord interpretations of this shape

Dm7

7sus

G7sus

7♯9

D♯7♯9

Δ♯5

AΔ♯5

m7♭5

Em7♭5

6/9

F6/9

All six cells

Cell	Voicing	m7	7sus	7♯9	Δ♯5	m7♭5	6/9
1	B–E–F–A	Dm7	G7sus	D♯7♯9	AΔ♯5	Em7♭5	F6/9
2	E♭–A♭–A–D	G♭m7	C♭7sus	G7♯9	D♭Δ♯5	A♭m7♭5	A6/9
3	G–C–D♭–F	B♭m7	E♭7sus	B7♯9	F♯Δ♯5	Cm7♭5	D♭6/9
4	C–F–G♭–B♭	E♭m7	A♭7sus	E7♯9	BΔ♯5	Fm7♭5	G♭6/9
5	F–B♭–B–E♭	A♭m7	D♭7sus	A7♯9	EΔ♯5	B♭m7♭5	B6/9
6	A–D–E♭–G	Cm7	F7sus	C♯7♯9	GΔ♯5	Dm7♭5	E♭6/9

How to practise

Play one cell with both hands together — left hand finds the implied root, right hand plays the four notes.
Keep the right-hand shape and rotate the bass through all six chord interpretations. Notice how dramatically the colour changes.
Move up a perfect fourth to the next cell. The shape contour stays identical; only the keys change.
String two cells together as a ii-V — the boxes are designed to voice-lead by step.

Frequently asked

Why no root?

Two reasons. First, in a band the bass player has the root covered. Second, leaving out the root makes the upper structure shape work for many chords at once — that is the whole point of the system.

Are these chord shapes fixed?

The pitch-class set is fixed. The exact octave you place each note in is up to you and the voice-leading context. Most pianists keep the shape inside one octave to start, then spread it once it's under their fingers.

How does Box I relate to the other boxes?

Box I, II, III, and IV are four rotations of the same pitch-class set. Choose the one whose lowest note voice-leads best from your previous chord. Box V is a separate shape used for ♯11, alt, sus♭9 and minor-major colours.

Try these voicings in a tool

Pull up the Chord Finder for any chord in the tables above and you'll see the shape on the keyboard. Drill the cells against a click on the Chord Drill.

Voicing Boxes Series

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Voicing Boxes Overview

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