m7♭5 and dim7

The half-diminished: m7♭5

Formula: 1, ♭3, ♭5, ♭7. On B: B, D, F, A. It’s a minor 7 chord with a flattened fifth. It’s written Bm7♭5 or Bø.

You already know it without realizing: it’s the chord on the 7^th degree of the major scale (B° in the table of keys), with its seventh.

e|---------------------|
B|-3-------------------|
G|-2---------4---------|
D|-3-----3-7---7-3-----|
A|-2-2-5-----------5-2-|
E|---------------------|

Chord fingering: A string at the 2^nd fret (B), D string at the 3^rd (F), G string at the 2^nd (A), B string at the 3^rd (D).

The diminished 7: dim7

Formula: 1, ♭3, ♭5, ♭♭7. On B: B, D, F, A♭. All its notes are a minor third apart: the shape repeats every three frets. Bdim7, Ddim7, Fdim7 and A♭dim7 are the same chord, inverted.

e|---------------------|
B|-3-------------------|
G|-1---------4---------|
D|-3-----3-6---6-3-----|
A|-2-2-5-----------5-2-|
E|---------------------|

It’s the passing chord par excellence: slipped between two chords a whole step apart, it walks the bass up a half step (C, C#dim7, Dm).

The minor ii-V-i

In major, the ii-V-I is Dm7, G7, Cmaj7. In minor, the ii becomes m7♭5: Bm7♭5, E7, Am. You hear it in countless jazz and bossa nova standards.

e|---0-0-|
B|-3-0-1-|
G|-2-1-2-|
D|-3-0-2-|
A|-2-2-0-|
E|---0---|

In a solo: the Bm7♭5 arpeggio, then target G# over E7 (its third, the leading tone of A minor), then C over Am. That G# comes from the harmonic minor scale, which you’ll meet in step 5.

Exercises

1. Both chords, then their arpeggios, at 60.
2. The climbing dim7: the same shape at the 2^nd, 5^th, 8^th and 11^th fret. Listen: it’s the same chord.
3. The minor ii-V-i on a loop, playing each chord’s arpeggio.

You’ve got it when…

• You can name the notes of Bm7♭5 and Bdim7
• You play the m7♭5 and dim7 arpeggios at 70
• You play the minor ii-V-i Bm7♭5, E7, Am, in chords then in arpeggios