Chords in B altered diminished

B° · Cm · D° · E♭+ · Fm · G · A♭

The course explains what this page shows in Lesson 19 · Harmonising the scale.

The chords in B altered diminished

  1. i°B°B°7
  2. iiCmCmMaj7
  3. iii°D°Dm7♭5
  4. IV+E♭+E♭+maj7
  5. vFmFm7
  6. VIGG7
  7. VIIA♭A♭maj7

The chords of B altered diminished are B°, Cm, D°, E♭+, Fm, G and A♭. With a seventh added they become B°7, CmMaj7, Dm7♭5, E♭+maj7, Fm7, G7 and A♭maj7.

If you stack every other note of B altered diminished, starting from each degree in turn, these are the chords you get. Nobody chose them: each one is built from the scale's own notes, arranged in thirds.

Every chord, where it lives

i°B°iiCmiii°D°IV+E♭+vFmVIGVIIA♭
Open♭51151♭3♭51♭31131
Fret 11♭5♭3♭5151♭3151♭3♭3♭51♭31♯513151♭351
Fret 22fr1♭51♭32fr13♯5♯512fr13351
Fret 33fr151♭353fr1♭51♭31♭53fr133♯5133fr151♭33fr1513513fr13351
Fret 44fr1♭5♭3♭54fr1♯513♯514fr1♭3♭354fr151351
Fret 55fr1♭3♭3♭55fr1♭51♭35fr1313♯55fr151♭355fr1513
Fret 66fr1♭5♭3♭56fr1♭3♭3516fr1♯513♯56fr151♭3156fr1513
Fret 77fr1♭51♭37fr13♯57fr133513
Fret 88fr151♭3518fr1♭3♭3♭58fr151♭358fr1513158fr133513
Fret 99fr1♭51♭39fr1♭5♭3♭59fr13♯53♯59fr131359fr151315
Fret 1010fr1♭3♭3♭51♭310fr151♭310fr1♭51♭310fr1313♯510fr1513510fr13135
Fret 1111fr1♭3♭3511fr1♯513♯5111fr1♭3♭35111fr15135
Fret 1212fr1♭51♭31♭5

The grid places seven chords across thirteen home frets on 7-string guitar. Every chord is within reach from fret 2 and fret 5 and fret 7 and fret 8 and fret 10.

Read down a column to find one chord all over the neck. Each shape appears once, in the row for the fret it starts on. The line in the margin marks the rows your hand covers from a position where every chord of the key is within reach. In this key those positions are fret 2 and fret 5 and fret 7 and fret 8 and fret 10.

Shapes for each chord

B° i°
♭51♭51♭5♭51♭5♭3♭5
Cm ii
151♭3151♭351♭315151♭315
D° iii°
♭51♭31♭3♭3♭51♭3♭5♭31♭3♭51
E♭+ IV+
1134fr1♯513♯513fr133♯513
Fm v
151♭351151♭35151♭35♭31♭351
G VI
13113511311
A♭ VII
4fr1513514fr151354fr13514fr1513

These are the most playable shapes for each chord, starting from the lowest position. Every shape fits within the reach of one hand, so none of them needs a finger you do not have.

Progressions in B altered diminished

Three chord
  1. i°B°
  2. IV+E♭+
  3. vFm
B°i°E♭+IV+FmvDE♭FFGA♭BBC+1+2+2+1+1

One of the six lines between these chords is flat: that note belongs to both chords, so it stays where it is. No voice moves more than two semitones.

Every one of these chords comes from B altered diminished.

Axis
  1. i°B°
  2. vFm
  3. VIG
  4. IV+E♭+
B°i°FmvGVIE♭+IV+DCBBFFDE♭BA♭GG−2−1−3+1−3−1

Three of the nine lines between these chords are flat: those notes belong to both chords, so they stay where they are. No voice moves more than three semitones.

Every one of these chords comes from B altered diminished.

Doo-wop
  1. i°B°
  2. VIG
  3. IV+E♭+
  4. vFm
B°i°GVIE♭+IV+FmvDDE♭FFGGA♭BBBC+1+2+2+1+1

Four of the nine lines between these chords are flat: those notes belong to both chords, so they stay where they are. No voice moves more than two semitones.

Every one of these chords comes from B altered diminished.

ii–V–I
  1. iimaj7CmMaj7
  2. v7Fm7
  3. i°7B°7
CmMaj7iimaj7Fm7v7B°7i°7CCBE♭E♭DGFFBA♭A♭−1−1−2−3

Four of the eight lines between these chords are flat: those notes belong to both chords, so they stay where they are. No voice moves more than three semitones.

These are the third and the seventh of each chord on their own. Together they decide whether a chord is major, minor or dominant, which is why they are called guide tones. If you play only these two notes, you can still hear the chords change. If you play only the root and the fifth, you cannot. 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 three semitones.

CmMaj7iimaj7Fm7v7B°7i°7E♭E♭DBA♭A♭−1−3

Every one of these chords comes from B altered diminished.

Rhythm changes
  1. i°7B°7
  2. VI7G7
  3. iimaj7CmMaj7
  4. v7Fm7
B°7i°7G7VI7CmMaj7iimaj7Fm7v7DDCCFFE♭E♭A♭GGFBBBA♭−2−2−1−2−3

Seven of the twelve lines between these chords are flat: those notes belong to both chords, so they stay where they are. No voice moves more than three semitones.

This diagram again follows only the guide tones, the third and seventh of each chord. Two of the six lines between these chords are flat: those notes belong to both chords, so they stay where they are. No voice moves more than three semitones.

B°7i°7G7VI7CmMaj7iimaj7Fm7v7DBBA♭A♭FE♭E♭−3−3−3−2

Every one of these chords comes from B altered diminished.

Twelve-bar blues
  1. I7B7
  2. I7B7
  3. I7B7
  4. I7B7
  5. IV7E♭7
  6. IV7E♭7
  7. I7B7
  8. I7B7
  9. V7F7
  10. IV7E♭7
  11. I7B7
  12. V7F7
B7I7E♭7IV7B7I7F7V7E♭7IV7B7I7F7V7D♯E♭D♯E♭E♭D♯E♭F♯GF♯FGF♯FAB♭AAB♭AABD♭BCD♭BC+1−1−1+2−1−1+1−1+1−1+2−2+1+1−2+1

Eight of the 24 lines between these chords are flat: those notes belong to both chords, so they stay where they are. 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.

This diagram again follows only the guide tones, the third and seventh of each chord. Four of the twelve lines between these chords are flat: those notes belong to both chords, so they stay where they are. 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.

B7I7E♭7IV7B7I7F7V7E♭7IV7B7I7F7V7D♯D♭D♯E♭D♭D♯E♭AGAAGAA−2+2−2+2−2+2−2+2

None of these chords belongs entirely to B altered diminished: all three of them use notes the key does not contain (F♯, A, B♭ and D♭). No single key contains all of them. Every one is a dominant seventh, and a dominant seventh pulls towards the chord whose root is a fifth below its own, one step anticlockwise on the circle (B7 → E, E♭7 → A♭, F7 → B♭). A chord drawn dashed, here and on the circle, goes outside the key.

There are six progressions in B altered diminished, including Three chord (B° E♭+ Fm) and Axis (B° Fm G E♭+).

Each row is one progression. It is written first in roman numerals, which name each chord by the degree of the scale it is built on, and then as the chords those numerals stand for in this key. A dashed outline means the chord borrows a note that B altered diminished does not contain. Under each progression, a diagram follows every note from one chord to the next. A flat line is a note that stays where it is, and a sloped line is labelled with the number of semitones the note moves.

B altered diminished on the circle of fifths

—1♯2♯3♯4♯5♯6♯5♭4♭3♭2♭1♭CAmGVIEmD°iii°BmAF♯mEC♯mB°i°G♯mF♯D♯mD♭B♭mA♭VIIFmvE♭+IV+CmiiB♭GmFDmB AlteredDiminished3♭

Each step clockwise around the wheel moves up a perfect fifth and adds a sharp to the key signature, or takes a flat away. The small numbers around the rim show each key's signature. B altered diminished has three flats in its key signature. Its B is not part of the signature, so it is written as an accidental each time it appears.

Why the chords land where they do

The two rings work in pairs. Each minor key on the inner ring is the relative minor of the major key just outside it: the two are built from the same seven notes and share a key signature. C major and A minor are one such pair.

Its two major chords, G and A♭ (the VI and VII), sit five steps apart on the outer ring rather than side by side. Its two minor chords, Cm and Fm (the ii and v), sit together on the inner ring. That accounts for four of the seven chords, and no single block contains them.

The other three chords sit apart and are outlined on their own. B°, the i°, is three steps from the nearest chord in the group. D°, the iii°, is one step from the nearest chord in the group. E♭+, the IV+, shares a spoke with Cm.

The wheel is still a map of harmonic distance, but this scale covers more of it than a major key does. Chords that sit close together sound as though they belong to one key, while each of the three that sit apart sounds like a departure. That sense of movement is a large part of this scale's character.

One step, on the neck

On the guitar, a perfect fifth is a shape you already know: the power chord. Play a root, then the note two frets higher on the next string up. Here it starts on B.

BEADGBE12345BF♯C♯

Now think of it as a chain. The F♯ you are already fretting is the fifth of B, and it is also the root of the next chord clockwise. Play the same shape starting from F♯ and you reach C♯. B → F♯ → C♯ is two steps around the wheel, and the same movement repeated up the neck.

The shape works here because these strings are a fourth apart. On the G–B pair the distance changes, so the fifth moves to a different fret. That is the one place this tuning breaks the pattern, and the reason familiar chord shapes change on the higher strings.

B altered diminished has three flats in its key signature. Its B is written as an accidental. Four of its chords sit close together on the circle of fifths, and three sit apart.

Four of B altered diminished's seven chords sit near each other on the wheel, and three sit apart.