Altered chords

Altered chords are a special category of chords that - as the name implies - alter other chords. There are, for example, altered dominant seventh chords with a flattened or a sharp fifth: 7-5 and 7+5.

See diagrams of altered chords:

C7-5 D7-5 E7-5 F7-5 G7-5 A7-5 B7-5

C7+5 D7+5 E7+5 F7+5 G7+5 A7+5 B7+5

C7-9 D7-9 E7-9 F7-9 G7-9 A7-9 B7-9

C7+9 D7+9 E7+9 F7+9 G7+9 A7+9 B7+9

C7+11 D7+11 E7+11 F7+11 G7+11 A7+11 B7+11

C13+11 D13+11 E13+11 F13+11 G13+11 A13+11 B13+11


Theory of this chord category are presented here.

We can compare a normal dominant seventh chord with altered dominant chords in the note of C:

C7: C – E – G – Bb
C7-5 (C7b5): C – E – Gb – Bb
C7+5 (C7#5): C – E – G# – Bb

Concerning chord names, instead of minus (-), flat (b) are sometimes used and instead of plus (+), sharp (#) are sometime used. Therefore, C7-5 and C7b5 is the same chord and C7+5 and C7#5 is the same chord. Note also that C7+5 contains the same notes as Caug7.

Comparing a normal dominant seventh chord with another pair of altered chords.

C7: C – E – G – Bb
C7-9 (C7b9): C – E – G – Bb – Db
C7+9 (C7#9): C – E – G – Bb – D#

The names of these chords are C dominant seventh, sharp ninth and C dominant seventh, flat ninth. C7-9 and C7+9 could also be written C7b9 and C7#9 respectively.

Comparing with a third group of altered seventh chords.

C7: C – E – G – Bb
C7+11 (C7#11): C – E – G – Bb – F#

The name of this chord is C dominant seventh, eleventh sharp ninth (a correspondent C dominant seventh, eleventh flat ninth does not exist). C7+11 could also be written C7#11.

Other altered chords

Finally, lets look at some less common categories.

Altered ninth and thirteenth chords.

C9#11: C – E – G – Bb – D – F#
C13b9: C – E – G – Bb – Db – F – A
C13#11: C – E – G – Bb – D – F# – A

Continued reading: altered chords as substitutions and Altered chord on Wikipedia

Chord categories

Major chords Minor chords Seventh chords Extended chords Sus chords Dim chords Aug Chords Add Chords Altered Chords