Seventh chords represent an essential step in expanding any musician’s musical vocabulary. Their complexity adds depth and makes the song shine against its peers.
To understand these chords, think of them in two parts: the base chord and then a seventh added on top. Draw the root of the chord onto the staff before writing notes that correspond to its third, fifth, and seventh degree above it.
Major Seventh
Major seventh chords are musical forms composed of the first, third, fifth and seventh notes from any major scale. Commonly used in jazz and blues music to produce fuller sounds, major seventh chords are an ideal way to add dimension and depth.
Maj7 chords can be easily found at certain scale degrees and add depth and colour to your progressions. Their construction is straightforward and they’re highly effective when used appropriately.
As with triads, seventh chords are distinguished according to their quality and inversion (this will be covered further in the Chord Inversion and Figured Bass chapter). To identify its quality on a staff, draw its root and then name all three generic intervals above it: third, fifth and seventh intervals.
Seventh chords composed of do and fa (1 and 4) contain a minor triad and major seventh, while those constructed using sol and ti (5 and 7) with raised leading tone contain an inverted diminished triad and minor seventh.
Minor Seventh
The minor seventh chord is an indispensable voicing in jazz, often used to add tension in chord progressions. Additionally, it works great over minor triads to emphasize more bluesy feel in songs.
Minor seventh chords feature close spacing among its notes, similar to triads. The lowest note, known as the root, serves as the anchor of this structure while all others are named according to their interval distance from this origin as described by a note interval table.
Minor seven chords are created using the pattern of a minor third, major third, and minor seventh above any root note: G-C-Eb-A is one such minor seven chord. You can add a flattened seventh for a minor 11 chord; these chords can serve as effective alternatives to dominant chords in minor keys when used together with secondary dominant or diminished chords.
Dominant Seventh
A dominant seventh chord adds an additional note to a major triad chord, giving it a stronger sound. However, its tones tend to be darker and less bright than its major counterpart; as such it’s often used to create tension within songs.
Not only can this chord serve to resolve with its falling-fifth root motion to the tonic, it can also act as a modulation. When followed by another chord from its key – such as tonic chord – this gives a strong push toward new key.
Dominant seventh chords can harmonize all the notes in a major scale with the exception of its subtonic (sixth) and dominant (fifth) tones. When including a flat seventh tone, however, an unstable tritone interval emerges that requires resolution; hence making dominant seventh chords an inherently tension-filled and dissonant musical formation.
Half-Diminished Seventh
While major seventh chords tend to feel comfortable and stable, diminished seventh chords tend to create tension as their flattened fifth (b5) interval causes dissonance. Therefore, diminished seventh chords should only be played for short durations as they cause dissonance between chords; they are most commonly used between chords to create dissonance or connect other chords. Surprisingly enough, their interval structure mirrors that of triad chords; however the key difference lies in that major fifth of triads is major while diminished sevenths have minor fifths instead.
This chord, commonly written as m7b5, is often abbreviated to “o7,” although in bass clef it should read as “m7(b5).” It’s used frequently in jazz music for its melancholic tone and can often function as either the vi chord in major keys or chord ii in parallel minor keys – and is frequently included as part of blues progressions.