Lesson 36 · Part 6, Jazz blues and the capstone

Guide tones

Two notes tell you which chord you are on — the third and the seventh — and following just those two through the changes is the smallest thing you can play that still sounds like the harmony.

A dominant seventh has four notes, and two of them are doing the work. The root only says which chord it is, and the fifth says almost nothing — take either of them away and the chord still sounds like itself. The third and the seventh are different: the third decides major or minor, the seventh decides whether the chord wants to move. Lose those and there is no chord left.

Players call them guide tones, and the useful thing about them is that they are two notes instead of four, which means you can follow them as a line.

The thirds and the sevenths of a blues

  1. I7A7
  2. I7A7
  3. I7A7
  4. I7A7
  5. IV7D7
  6. IV7D7
  7. I7A7
  8. I7A7
  9. V7E7
  10. IV7D7
  11. I7A7
  12. V7E7
A7I7D7IV7A7I7E7V7D7IV7A7I7E7V7C♯CC♯DCC♯DGF♯GG♯F♯GG♯−1+1+1−2+1+1−1+1+1−2+1+1

None of the twelve lines between these chords is flat, so every voice moves at every change. No voice moves more than two semitones. The progression lasts twelve bars, but a repeated chord is not a change, so the ladder shows only the six places where the harmony moves.

Two of these chords go outside A major, borrowing G and C (A7, D7). No single key contains all of them. Every one is a dominant seventh, and a dominant seventh pulls toward the chord whose root is a fifth below its own, one step anticlockwise on the circle (A7 → D, D7 → G, E7 → A). A chord drawn dashed, here and on the circle, goes outside the key.

Twelve-bar blues in A Major uses A7, D7 and E7.

The chords appear in the order the bars play them, and the diagram below follows the same chords two notes at a time: the third and the seventh, and nothing else. A dashed outline marks a chord that borrows a note A Major does not contain.

Read the sentence under the ladder. In a plain blues every one of those lines moves at every change — there is no note that belongs to two chords in a row — and none of them travels more than a whole tone. So the whole harmony of twelve bars is two voices, each stepping a fret or two at a time.

Why jazz players hear a ii–V as one thing

The same two notes, through a ii–V–I

  1. ii7Bm7
  2. V7E7
  3. Imaj7Amaj7
Bm7ii7E7V7Amaj7Imaj7DDC♯AG♯G♯−1−1

Two of the four lines between these chords are flat: those notes belong to both chords, so they stay where they are. No voice moves more than one semitone.

Every one of these chords comes from A major.

ii–V–I in A Major uses Bm7, E7 and Amaj7.

The chords appear in the order the bars play them, and the diagram below follows the same chords two notes at a time: the third and the seventh, and nothing else. A dashed outline marks a chord that borrows a note A Major does not contain.

Now half of them hold. Two of the four lines are flat, which means those notes belong to both chords and stay where they are, and the ones that do move move by a single semitone. That is why a ii–V sounds like one gesture rather than two chords: almost nothing happens, and what does happen is as small as it can be.

Part 6 opened with a form full of ii–V pairs. This is what they feel like from the inside, and it is why adding them makes a blues sound smoother rather than busier.

What to do with them

Play the two lines and nothing else, one note to a bar, through a whole chorus. It will feel like too little. Then play your box again and notice that you can hear where the guide tones are even when you are not playing them — which is the point. You are not learning a new thing to play; you are learning what your ear was already listening for.

This lesson was drafted with the help of AI, so it may contain a mistake. Its diagrams are drawn by Everyfret’s own software. How Everyfret is made