A chord which is also referred to as
minor seventh flat 5 (m7b5), since it is exactly that... a
minor seventh with a flat fifth. The tones present in the chord are the
root, a
flat third, a
flat fifth, and a
flat seventh (this also makes it a
diminished triad with a
flat seventh stuck at the end), and if the seventh were flatted once again, it would be a
fully-diminished seventh. In strictly
diatonic music, one would play the
half-diminished seventh off of the seventh tone in a major key, or the second tone in a minor key. If you're soloing and another instrument is playing a half-diminished seventh, you can get away with playing the
minor blues scale,
locrian mode, or
altered scale of the chord's tonic note. This chord resolves quite happily to the
dominant seventh two whole steps down (eg, Bm7b5
-> G7).
We now deviate from theory to spell out a few half-diminished seventh chords:
- Am7b5 contains the notes A C Eb G
- Fm7b5 contains the notes F Ab Cb Eb
- Cm7b5 contains the notes C Eb Gb Bb
If you happen to play the guitar, here are the
CAGED forms of the chord on the guitar neck:
---2--------------------0------1---
---1------1-------------3------1---
---3------0-----4-------0------1---
---1------1-----3-------0------0---
---3------0-----1-------1----------
----------------3-------0----------
Cm7b5 Am7b5 Gm7b5 Em7b5 Dm7b5
By sliding those shapes around and using
this handy information, you can form any
inversion of a half-diminished seventh you damn well please.