Module 14: Modern harmony and rhythmLesson 1advanced⏱ 90 min + 20 min daily for two weeks

Quartal voicings and modal comping

Build voicings from stacked 4ths, learn the "So What" shape, move quartal stacks through a mode on every string set, and comp a modal vamp the way the 1960s rhythm sections did.

Why 4ths

Every voicing you have learned so far is built in 3rds: shells, drop 2, drop 3 and rootless shapes all stack a 3rd on a 3rd, and each one tells the listener exactly which chord it is. That clarity is a virtue over fast-moving changes. It becomes a limitation when a tune sits on one chord for sixteen bars. Modal jazz, from the late 1950s onward, needed harmony that could stay on D minor for a long time without sounding like a stuck record, and the solution that McCoy Tyner, Bill Evans and Herbie Hancock arrived at was to stack 4ths instead of 3rds. A stack of 4ths is ambiguous: the same three notes can belong to four or five different chords, so the voicing suggests a mode rather than a chord, and the soloist is free. It is also physically ideal for the guitar, whose strings are tuned in 4ths: a stack of 4ths lies across the strings at (nearly) the same fret.

This lesson gives you the diatonic 4th stacks in D Dorian on every string set, the famous "So What" voicing and where its one 3rd comes from, a method for moving the shapes through any mode, and the rhythmic language of modal comping. The companion lesson on upper-structure triads does the same job for dominant chords.

Diatonic 4ths in D Dorian

Take the D Dorian scale and build a chord on each degree by stacking every other fourth note instead of every other third. Most of the resulting intervals are perfect 4ths; one of them, F to B, is an augmented 4th (a tritone), because that is where the mode's half steps fall. Stacks containing the F–B tritone sound noticeably harder and brighter; stacks of pure perfect 4ths sound open and hollow. You will use both.

Four-note stacks on strings 5-4-3-2

The exercise below walks the seven four-note stacks up the neck on strings 5-4-3-2, starting from the stack built on A at the nut and ending with the same stack an octave higher. Play each chord with four fingers or with a partial barre where three strings share a fret; let the chords ring into each other and listen for the two stacks that contain the tritone (the ones built on F and on G).

\tempo 72
.
\ts 4 4
(0.5 0.4 0.3 1.2).2{ch "Dm7"} (2.5 2.4 2.3 3.2).2 | (3.5 3.4 4.3 5.2).2 (5.5 5.4 5.3 6.2).2 | (7.5 7.4 7.3 8.2).2 (8.5 9.4 9.3 10.2).2 | (10.5 10.4 10.3 12.2).2 (12.5 12.4 12.3 13.2).2 |

The chord symbol Dm7 is there as the chart symbol of the vamp, not a description of each chord. Several of these stacks are not D minor chords at all when taken alone; they are D Dorian colours, and the bass player's D is what makes them sound like D minor.

Three-note stacks on 4-3-2 and 3-2-1

Three-note stacks are lighter and more practical for comping behind a soloist. Here are the same seven degrees on the top string sets. Memorise the pattern of frets rather than the notes: on strings 3-2-1 most stacks are "one fret, then the same fret twice", and on 4-3-2 "the same fret twice, then one fret higher".

\tempo 80
.
\ts 4 4
(2.3 3.2 3.1).4{ch "Dm7"} (4.3 5.2 5.1).4 (5.3 6.2 7.1).4 (7.3 8.2 8.1).4 | (9.3 10.2 10.1).4 (10.3 12.2 12.1).4 (12.3 13.2 13.1).2 | (0.4 0.3 1.2).4 (2.4 2.3 3.2).4 (3.4 4.3 5.2).4 (5.4 5.3 6.2).4 | (7.4 7.3 8.2).4 (9.4 9.3 10.2).4 (10.4 10.3 12.2).4 (12.4 12.3 13.2).4 |

The "So What" voicing

Bill Evans's voicing on Miles Davis's So What (1959) is the most imitated chord of modal jazz: three perfect 4ths with a major 3rd on top. The 3rd on top is what stops the chord sounding like an unfinished exercise; it gives the stack a top note that behaves like a melody. On guitar the five-note version sits on strings 5 to 1 with every string but one at the same fret.

The engine names each shape from its lowest note, so the shapes below are labelled from the chords whose tones they contain. The first is the four-note stack with D in the bass (root, 11th, 7th, 9th of Dm11). The second is the full five-note Evans voicing, which starts on E: taken by itself it is an Em11, and that ambiguity is exactly the point. Over a bass player's D it reads 9–5–R–11–13 of D minor, as the fretboard map shows.

The third and fourth shapes are the same two voicings moved up one fret, which is what happens at the bridge of the tune: the whole band shifts from D Dorian to Eb Dorian and back. That is modal harmony in one gesture: a parallel shift of an entire sound, not a chord change in the functional sense. Practise alternating the two positions in time, two bars each, with a metronome on 2 and 4.

Moving quartal shapes through a mode

The procedure for any mode is the same:

1. Write out the scale.
2. Pick a string set and a stack size (three or four notes).
3. Build the stack on each degree by taking every fourth scale note.
4. Play them in order up the neck, then in the order of the scale degrees you would like to hear as a top voice (the top note is the melody of your comping).

Dorian is only the most common case. The same stacks over a dominant pedal give the suspended, floating sound of modal dominant vamps. In G Mixolydian the tritone falls between B and F, so the "bent" shapes are the ones built on B and on F. The vamp below keeps a G in the bass under three-note stacks on strings 4-3-2.

\tempo 100
.
\ts 4 4
(3.6 5.4 5.3 6.2).4{ch "G7sus4"} r.8 (3.6 7.4 7.3 8.2).8 -.2.4 (3.6 5.4 5.3 6.2).4 | r.8 (3.6 10.4 10.3 12.2).8 -.2.4 (3.6 9.4 9.3 10.2).8 r.8 (3.6 12.4 12.3 13.2).4 | (3.6 2.4 2.3 3.2).4 r.8 (3.6 3.4 4.3 5.2).8 -.2.4 (3.6 5.4 5.3 6.2).4 | r.4 (3.6 7.4 7.3 8.2).8 r.8 (3.6 5.4 5.3 6.2).2 |

Quartal shapes over a ii-V-I

Quartal stacks are not only for modal tunes. Over a ii–V–I the stack built on the 9th of the ii chord, the stack built on the 7th of the V chord and a 4th-based voicing of the I chord give a modern, open sound with almost no hand movement. Each chord here is checked note for note against its symbol: the ii stack is 9–5–R–11 of Dm11, the V stack is b7–3–13–9 of G13 (the tritone is inside it), and the I voicing is 9–5–R–3 of C6/9, which is the first shape of the lesson moved down two frets.

\tempo 120
.
\ts 4 4
(7.5 7.4 7.3 8.2).4{d ch "Dm11"} (7.5 7.4 7.3 8.2).8 r.2 | r.8 (8.5 9.4 9.3 10.2).8{ch "G13"} -.2.4 (8.5 9.4 9.3 10.2).4 r.4 | (5.5 5.4 5.3 5.2).1{ch "C6/9"} | r.4 (5.5 5.4 5.3 5.2).4 r.8 (5.5 5.4 5.3 5.2).8 -.2.4 |

Modal comping rhythms

A functional progression supplies its own momentum; a modal vamp does not, so the comping has to. Four principles, all audible on the classic Blue Note and Impulse recordings of the 1960s:

• Oscillate between two or three stacks, not one. The movement of the top voice is the "melody" of your comping; a single repeated chord is static within two bars.
• Play the anticipation. Chords land on the and of 4 and the and of 2 more often than on downbeats, as in the comping rhythms lesson, but with longer rests between figures.
• Pedal in the bass. A low root or 5th held under moving stacks (Tyner's left hand) is the sound of modal piano, and the guitar can imitate it with the thumb.
• Leave holes. Modal soloists play long lines; a comper who fills every beat makes the music busy. Two-bar figure, two bars of near-silence, is a normal ratio.

The vamp below puts these together in two voices: the thumb holds a D pedal on the 6th string while the fingers move three-note stacks on strings 4-3-2 in a rhythm that lands mostly on upbeats.

\tempo 132
.
\ts 4 4
\voice 10.6.2{d ch "Dm7"} 10.6.4 | 10.6.2{d} 10.6.4 | 10.6.2{d} 10.6.4 | 10.6.2{d} 10.6.4 |
\voice :8 r (7.4 7.3 8.2) (-.4 -.3 -.2).4 :8 r (9.4 9.3 10.2) (-.4 -.3 -.2).4 | r.4 (10.4 10.3 12.2).4 :8 r (9.4 9.3 10.2) (-.4 -.3 -.2).4 | :8 r (7.4 7.3 8.2) (-.4 -.3 -.2).4 :8 r (5.4 5.3 6.2) (-.4 -.3 -.2).4 | r.2 (7.4 7.3 8.2).4 r.4 |

Exercises

1. The seven four-note stacks on strings 5-4-3-2 (the first example), ascending and descending, 60 bpm, half notes. Say the degree each stack is built on as you play it. Then the same on strings 6-5-4-3 by moving every shape one string lower (the shapes are identical because strings 6-5-4-3 are all tuned in 4ths).
2. Three-note stacks on 3-2-1 and 4-3-2 as written, then in random order, aiming for a specific top note each time.
3. So What shift. Two bars of the Dm11 and Em11 shapes in D Dorian, two bars one fret higher in Eb Dorian, continuously, 120 bpm, click on 2 and 4.
4. G7sus4 vamp as written, then invent your own two-bar rhythm using only the stacks built on G, D and C.
5. Quartal ii-V-I in C, then transposed to F, Bb and Eb by moving the whole three-shape cell (the shapes do not change; only the position does).
6. Pedal vamp as written for four minutes without stopping, keeping the thumb even. Record it and listen to whether the pedal note is steady.

Quiz