# Diminished 7th and minor-major 7th

*Module 10 · Lesson 2: Seventh chords · BazzLow*

> Know the two seventh chords that come from the harmonic minor scale.

Before this lesson: [10.1 The four main seventh chords](https://bazzlow.com/en/seventh-chords/four-seventh-chords/) · [6.4 The harmonic minor scale](https://bazzlow.com/en/minor-scales/harmonic-minor-scale/)

The harmonic minor scale of lesson 6.4 gives two more seventh chords. Both sound dark and tense.

## Diminished 7th

The **diminished 7th** chord (also **fully diminished**) has the symbol **C°7**. Its formula is **1 ♭3 ♭5 𝄫7**: C E♭ G♭ B𝄫, three minor 3rds stacked. The 𝄫7 sounds like a major 6th but is written as a 7th, B𝄫 and not A, because the chord is built in thirds (lesson 4.4). **Half-diminished** (ø7) and fully diminished (°7) differ only in the 7th: ♭7 versus 𝄫7.

It is **symmetrical**: every note is a minor 3rd apart. So there are only **three different-sounding** diminished 7th chords. C°7, E♭°7, G♭°7 and A°7 contain the same four pitches, spelled differently, and every one of the 12 roots belongs to one of the three groups.

*The 12 diminished 7th chords in three groups. Chords in the same group contain the same four pitches, spelled differently.*

| Group | Chord | Notes |
| --- | --- | --- |
| 1 | C°7 | C E♭ G♭ B𝄫 |
| 1 | E♭°7 | E♭ G♭ B𝄫 D𝄫 |
| 1 | G♭°7 | G♭ B𝄫 D𝄫 F𝄫 |
| 1 | A°7 | A C E♭ G♭ |
| 2 | D♭°7 | D♭ F♭ A𝄫 C𝄫 |
| 2 | E°7 | E G B♭ D♭ |
| 2 | G°7 | G B♭ D♭ F♭ |
| 2 | B♭°7 | B♭ D♭ F♭ A𝄫 |
| 3 | D°7 | D F A♭ C♭ |
| 3 | F°7 | F A♭ C♭ E𝄫 |
| 3 | A♭°7 | A♭ C♭ E𝄫 G𝄫 |
| 3 | B°7 | B D F A♭ |

It occurs naturally on the 7th degree of the **harmonic minor** (G♯°7 in Am), and acts like a dominant: tense, resolving to the tonic.

## Minor-major 7th

The **minor-major 7th**, symbol **Cm(maj7)**, is **1 ♭3 5 7**: C E♭ G B. It is a minor triad with a major 7th, the i chord of the harmonic or melodic minor. It sounds dark and tense, typical of film and jazz.

> **Diagram:** C°7: C E♭ G♭ B𝄫.

> **Diagram:** Cm(maj7): C E♭ G B.

One more chord appears in the harmonic minor: the **augmented major 7th** (+maj7, 1 3 ♯5 7) on the III degree. It is rare. It is mentioned for completeness, as it appears in the Key Chords tool.

## Try it

Play C°7 as an arpeggio, then move the same shape up 3 frets (E♭°7), and again. Notice that you keep playing the same four notes.

## New terms

- diminished seventh chord
- fully diminished
- minor-major seventh chord
- augmented major seventh

Page: https://bazzlow.com/en/seventh-chords/diminished-and-minor-major-seventh/