Module 3: Theory II: seventh chords and the ii–V–ILesson 3beginner⏱ 75 min + two weeks of daily cycle practice

The ii–V–I

Understand why the ii–V–I is the central progression in jazz, hear and play its guide tones, voice-lead it with four-note shapes, and arpeggiate it in every key.

Why one progression gets a whole lesson

Open any jazz chart and count how many bars are part of a ii–V–I. In most standards it is more than half. The progression appears in the home key, in the relative minor, in passing keys for two bars at a time, and in disguise inside blues and rhythm-changes turnarounds. If you can hear it, voice it and improvise over it in every key, you can play a large part of the repertoire; if you cannot, no amount of scale practice will help. This lesson is about the major-key version; lesson 4 covers the minor-key version.

The ii–V–I is powerful for three reasons that you now have the theory to understand:

1. It is the three functions in order. Subdominant (ii7), dominant (V7), tonic (Imaj7): departure, tension, arrival, in three chords.
2. Its roots move in descending 5ths. Each root is a perfect 5th below (or a perfect 4th above) the previous one. Root motion by 5ths is the strongest there is; the whole circle of fifths is one long chain of it.
3. Its guide tones move by step. The notes that define each chord slide to the notes that define the next by a half step or not at all. That is what makes it sound inevitable, and it is what you will learn to hear and play in the middle of this lesson.

Construction in major

Take the diatonic seventh chords of a major key from the previous lesson and pick degrees 2, 5 and 1. In C that gives the three chords below.

A few things to notice straight away. The ii chord is always minor seventh, the V always dominant seventh, the I always major seventh (or major sixth; a chart may write C6 or just C for the tonic, and all three mean the same job). The root of ii is a whole step above the root of I, and the root of V is a perfect 5th above I. So from any tonic you can find the other two chords in your head: go up a whole step for ii, up a 5th (or down a 4th) for V.

Here are the three chords in the five keys that occur most often in the repertoire:

Hearing the ii–V–I

Play the three chords with the drop-2 shapes from lesson 1, one bar each, then start again. Then play only V7 to Imaj7 and notice that it already sounds complete; the ii chord is a preparation that makes the arrival feel bigger. Then play ii7 and stop. It sounds unfinished, and your ear will supply the V7 for you. That expectation is exactly what improvisers play with.

Guide tones: the 3rd and the 7th

Each seventh chord has four notes, but two of them carry the identity of the chord: the 3rd (major or minor) and the 7th (major or minor). These are the guide tones. The root is supplied by the bass player, and the 5th is the same in major, minor and dominant chords, so it tells you little. Take any ii–V–I, play only the 3rds and 7ths, and the progression is instantly recognisable. Look at the chord table above and trace the guide tones through the three chords:

• ii7: the 7th of the ii chord falls a half step to become the 3rd of V7.
• ii7: the 3rd of the ii chord stays where it is and becomes the 7th of V7.
• V7: the 7th of V7 falls a half step to become the 3rd of Imaj7.
• V7: the 3rd of V7 stays and becomes the 7th of Imaj7.

So at each chord change, one guide tone moves down a half step and the other does not move at all. Two half steps, two common tones, and the whole progression is explained. Play it:

\tempo 72
.
\ts 4 4
:1 (3.4 5.3){ch "Dm7"} | (3.4 4.3){ch "G7"} | (2.4 4.3){ch "Cmaj7"} | (10.4 10.3){ch "Dm7"} | (9.4 10.3){ch "G7"} | (9.4 9.3){ch "Cmaj7"} |

This is the skeleton of all jazz comping and of most bebop lines. In Module 4 you will add the root under these pairs to make shell voicings; in Module 7 you will write melodic lines that pass through them. For now, learn to hear which note moves.

Guide-tone lines as melody

Played one note at a time, the guide tones make a melody of their own. The example below runs through a ii–V–I in F and then in Bb. In each bar the first note is one guide tone and the second is the other, so the line alternates and you hear the half-step resolutions as you cross each bar line.

\tempo 84
.
\ts 4 4
:2 3.4{ch "Gm7"} 3.3 | 2.4{ch "C7"} 3.3 | 2.3{ch "Fmaj7"} 2.4 | :1 2.3 |
:2 3.3{ch "Cm7"} 1.4 | 2.3{ch "F7"} 1.4 | 0.4{ch "Bbmaj7"} 2.3 | :1 1.5 |

Voice leading with four-note shapes

The guide-tone principle (move as little as possible, keep common tones) is what tells you which inversion of a chord to play. Here is a ii–V–I in C with drop-2 voicings on strings 5–4–3–2. The Dm7 and Cmaj7 are the root-position shapes from lesson 1; the G7 is the same chord family with the 5th in the bass, chosen because it is the closest G7 to the Dm7 shape. Between each pair of chords, two notes stay and two move by step.

\tempo 80
.
\ts 4 4
:1 (5.5 7.4 5.3 6.2){ch "Dm7"} | (5.5 5.4 4.3 6.2){ch "G7"} | (3.5 5.4 4.3 5.2){ch "Cmaj7"} | (3.5 5.4 4.3 5.2) |

Look at what each finger does. From Dm7 to G7, the 5th-string note stays, the 4th-string note moves down a whole step, the 3rd-string note moves down a half step, the 2nd-string note stays. From G7 to Cmaj7, the bass drops a whole step, the next two notes stay, and the top note moves down a half step. No finger ever moves more than two frets. That is what "voice leading" means, and it is why the same three chords sound smooth here and clumsy when you jump between three root-position shapes. Module 8 does this systematically for every inversion; here you only need to feel the difference.

The ii–V–I in all twelve keys

Jazz is played in all twelve keys, and ii–V–Is pass through all of them inside tunes. The table lists the chords in every key. Use it to check your answers while you practise the cycle; after a couple of weeks you should not need it.

The standard way to practise anything through twelve keys is the cycle of fourths: each new key is a perfect 4th higher (equivalently, a perfect 5th lower) than the last. The order is simply the first column of the table read in a different sequence: start on C, and each next key is the root of the previous key's IV chord. The advantage is that the I chord of one key becomes the V chord of the next, so the ii–V–Is chain together without a break and you never have to stop and think where to go.

Arpeggiating the ii–V–I

Improvisers outline the chords before they decorate them. Here is a ii–V–I in C arpeggiated in one position: up each chord from the root and back down, eighths, with the hand around frets 3–8 and the index finger covering frets 3 and 4.

\tempo 84
.
\ts 4 4
:8 5.5{ch "Dm7"} 3.4 7.4 5.3 3.2 5.3 7.4 3.4 | 5.4{ch "G7"} 4.3 7.3 6.2 8.2 6.2 7.3 4.3 |
3.5{ch "Cmaj7"} 7.5 5.4 4.3 5.3 4.3 5.4 7.5 | :1 (3.5 5.4 4.3 5.2) |

And here is a short original line made only of chord tones, so you can hear what arpeggios sound like when they are rearranged into something melodic. Every note is a chord tone of the chord in force; the only "rule" being followed is that the notes on the strong beats (1 and 3) are guide tones.

\tempo 100
.
\ts 4 4
:8 3.4{ch "Dm7"} 2.3 5.3 3.2 6.2 3.2 5.3 2.3 | 4.3{ch "G7"} 3.2 6.2 5.4 3.4 5.4 4.3 3.2 |
5.2{ch "Cmaj7"} 5.3 4.3 5.4 2.4 5.4 4.3 1.2 | :2 5.2 r |

Exercises

1. Guide tones only. Play the two-note guide-tone pairs through ii–V–I in C, F, Bb, Eb and G, on strings 4–3. Find the pairs yourself from the chord notes in the progression table: 3rd of ii, then 7th of ii, then work out which one moves. Say "moves" or "stays" for each note.
2. Guide-tone melody. Play the F and Bb guide-tone line, then write out and play the same line in Eb, Ab and G. Sing it before you play it.
3. Voice-led drop 2. Play the voice-led ii–V–I in C, then move the three shapes together up five frets (key of F), down two frets (Bb) and up seven frets (G). Keep saying which notes stay and which move.
4. Cycle of fourths with arpeggios. Starting in C, play the arpeggio example, then repeat it in F, Bb, Eb, Ab, Db, Gb, B, E, A, D, G and back to C. Find each new ii root a perfect 4th above the last. Slow is fine; continuous is the point.
5. Hear it in tunes. Listen to any recording of a standard with a chart in front of you and mark every ii–V–I with a bracket. Count how many bars are covered.

Quiz