Beyond the Common Seventh Chords
In the previous lesson, we explored how adding a seventh to a three-note chord structure creates a seventh chord. We looked at the construction of the most familiar seventh chords and began to understand how their different interval structures affect their sound.
However, these aren't the only combinations available.
We can also create seventh chords by extending augmented triads, combining minor triads with major sevenths, or adding sevenths to suspended chord structures.
Some of these chords are less common, but they introduce distinctive sounds and demonstrate how even small changes to a chord's intervals can produce very different results.
In this lesson, we'll explore these additional structures, how they're constructed, how they're written and where you might encounter them.
Minor-Major Seventh Chords
We briefly introduced the minor-major seventh chord in the previous lesson. Let's look at what makes it different from the more familiar minor seventh.
A minor seventh chord contains a minor third and a minor seventh. A minor-major seventh chord retains the minor third but uses a major seventh instead.
1 – ♭3 – 5 – 7
Compare this with C minor seventh: C – E♭ – G – B♭. The only difference is the seventh, which has been raised by one semitone.
This seemingly small change has a noticeable effect on the sound. The major seventh sits just one semitone below the root, creating a distinctive tension against the minor chord structure.
Minor-major seventh chords can be heard in jazz, film music and other styles that make use of more unusual harmonies. They also occur naturally when building a seventh chord on the first degree of the melodic minor scale in its ascending form.
Extending Augmented Triads
An augmented triad contains a major third and an augmented fifth.
1 – 3 – ♯5
Unlike a standard major triad, the fifth has been raised by one semitone. This raised fifth gives augmented chords their distinctive sound. We can extend the structure by adding either a major or minor seventh.
Augmented-Major Seventh Chords
1 – 3 – ♯5 – 7
This chord can be written as Cmaj7♯5 or C+maj7.
Augmented Dominant Seventh Chords
1 – 3 – ♯5 – ♭7
For example, C7♯5 can resolve to F major. The raised fifth, G♯, lies just one semitone below A, a note belonging to the F major chord.
Diminished-Major Seventh Chords
There is another possible combination: adding a major seventh to a diminished triad.
1 – ♭3 – ♭5 – 7
This chord can be written as Cdim(maj7). The combination is unusual because it places a major seventh above a diminished triad.
Why Is This Chord Uncommon?
Unlike major seventh, minor seventh and dominant seventh chords, the diminished-major seventh is not a standard part of the most familiar diatonic chord collections.
Suspended Chords with Sevenths
Suspended chords replace the third with either a major second or a perfect fourth.
sus2: 1 – 2 – 5
sus4: 1 – 4 – 5
Because neither structure contains a third, they are not classified as major or minor triads. Adding a seventh creates a four-note chord while retaining the suspended character.
Dominant Seventh Suspended Fourth (7sus4)
1 – 4 – 5 – ♭7
One common way of using this chord is to move from C7sus4 to C7. As the chord changes, F moves down by one semitone to E while the other notes remain the same.
Suspended Chords with Major Sevenths
Cmaj7sus4: C – F – G – B
Formula: 1 – 4 – 5 – 7
Cmaj7sus2: C – D – G – B
Formula: 1 – 2 – 5 – 7
Recognising Unusual Seventh-Chord Structures
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Cmaj7 → Cmaj7♯5: Raise the fifth.
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C7 → C7♯5: Raise the fifth.
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Cm7 → Cm(maj7): Raise the seventh.
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C7 → C7sus4: Replace the third with the fourth.
Putting the Theory into Practice
Choose a chord type from this lesson and compare it with the more familiar chord it is derived from. Start with C7 and then change it to C7♯5. Next, compare C7 with C7sus4. Finally, try moving from C7sus4 to C7, paying attention to how the F resolves down to E.
Summary
We've now expanded our understanding of seventh chords beyond the most familiar major, minor and dominant forms.
