Lesson 3b - Seventh Chords

Class Discussion

A seventh chord is a stack of 4 pitches, each seperated by a 3rd. As a reminder.

There are 5 types of seventh chords, and we will be using both of the common terms for them:

• Major major (abbreviated MM) or major seventh chord
• Major minor (abbreviated Mm) or dominant seventh chord
• Minor minor (abbreviated mm) or minor seventh chord
• Diminished minor (abbreviated dm) or *half-diminished seventh chord
• Diminished diminished (abbreviated dd) or fully-diminished seventh chord

These terms are interchangeable but they are typically used in different circles. We will refer to them as the pedagogical name (e.g. major major, etc.) and common name (e.g. major seventh chord, etc.).

The pedagogical names are useful in illustrating the structure of a seventh chord and is unsurprisingly often used by theory teachers. I asked the class to explain what the two words in “major major” meant, and the first suggestion was, “The first word is the triad quality (major triad on bottom), and the second word is the chord quality between the root and the 7th. This is close, but did not quite explain the true nature of the second word. The pedagogical naming system for seventh chords mixes a chord quality with an interval quality. The first word always describes the triad (the bottom three pitches) while the second word describes the interval quality between the root and the seventh chordal member. This interval is always a 7th.

• Major major (major seventh chord): major triad + M7
• Major minor (dominant seventh chord): major triad + m7
• Minor minor (minor seventh chord): minor triad +m7
• Diminished minor (half-diminished seventh chord): diminished triad + m7
• Diminished diminished (fully-diminished seventh chord): diminished triad + d7

Because the class had already been through a similar exercise for triads, they were able to quickly identifty the inversion figures as they relate to the intervals above the bass, not the root of the chord.

• Root position: 7 (7/5/3)
• First Inversion: 6/5 (6/5/3)
• Second Inversion: 4/3 (6/4/3)
• Third Inversion: 4/2 (6/4/2)

As a reminder, we will be using the term inversion figure to discuss this shorthand method of identifying inversions. Other systems refer to these same superscript numbers as figured bass, bass position Symbols, or figures, but we need not argue about which name is better. As long as the student understands the difference between inversion figures, true figured bass (i.e. Baroque system for writing keyboard harmonies), and the shorthand used in leadsheet notation, it does not actually matter which term is used.

Further Reading

From Open Music Theory

Seventh chords

A four-note chord whose pitch classes can be arranged as thirds is called a seventh chord.

Like with a triad, the pitch classes belonging to a seventh chord occupy adjacent positions (a four-pitch-class clump) on the circle of thirds. The four members of a seventh chord are the root, third, fifth, and seventh.

There are five qualities of seventh chords that appear in diatonic music: major seventh, dominant seventh, minor seventh, diminished seventh (also called fully-diminished), and half-diminished seventh. They are comprised of the following intervals above their roots:

• major seventh: M3, P5, and M7 above the root (or major triad with a major seventh)
• dominant seventh: M3, P5, and m7 above the root (or major triad with a minor seventh)
• minor seventh: m3, P5, and m7 above the root (or minor triad with a minor seventh)
• diminished seventh: m3, d5, and d7 above the root (or diminished triad with a diminished seventh)
• half-diminished seventh: m3, d5, and m7 above the root (or diminished triad with a minor seventh)

Following are the lead-sheet abbreviations for seventh-chord qualities:

• major seventh: maj7 or △7 (G^maj7 or G^△7)
• dominant seventh: 7 (B⁷)
• minor seventh: m7 (F♯^m7)
• diminished seventh: dim7 or °7 (D^dim7 or D^°7)
• half-diminished seventh: ⦰7 (A^⦰7)