7th Chords
From “7th Chords¨ in Music Theory for Electronic Music Producers
Triads are great, but we can go a step further and make our chords more colorful by using four notes in our chords instead of three. We call these 7th Chords.
Clearly, diads and triads are very common chord groupings (refer to 20240924121346-What_Chords_Are). But there are more groupings than just that. For example, there are what are called “7th chords,¨ or “VII chords,¨ which have four in-tune (mechanical) keys or their pitches instead of the three in-tune (mechanical) keys and pitches of a triad (Allen 2018, 99). To be clear (Allen 2018, 100):
From “7th Chords¨ in Music Theory for Electronic Music Producers
The number seven in the name “7th chord¨ doesn’t mean it has seven notes. It refers to the interval above a given root.
Chord naming
It seems the interval that an additional in-tune (mechanical) key or its pitch is beyond the triad for the given chord determines the number for which that chord is named, if it is neither a diad or a triad.
Chord naming exceptions
Are there any exceptions to the above apparent naming rule for post-triad chords?
The procedure for creating a 7th chord is just a continuation of the procedure for creating a triad (refer to Scale Degrees and Triadic Chord Construction).
That is, a 7th chord is built with the following procedure (Ibid):
From “7th Chords¨ in Music Theory for Electronic Music Producers
We start with a root, and go up the scale: skip the second, add the third, skip the fourth, add the fifth. Just like a regular triad. But in a 7th chord we continue on with the same scale: skip the sixth, and add the seventh.
The utility of 7th chords is that they “can give us a more refined feeling¨ (Allen 2018, 99):
From “7th Chords¨ in Music Theory for Electronic Music Producers
If a major chord is “happy,¨ a minor 7th chord can be “pretty.¨ If a minor chord is “sad,¨ a minor 7th chord could be “melancholy.¨
7th chords tend to be more common for a genre like jazz, and other adjacent genres (Ibid). It can have aesthetic utility insofar as:
From “7th Chords¨ in Music Theory for Electronic Music Producers
[…] 7th chords will give [a] track a “thicker¨ sound, […]
New Chord Qualities from the 7th Chord
The “thick¨ sound of 7th chords compared to triad chords may be due to the expanded expressiveness allowed by the additional qualities they can have. A triad chord has minor and major qualities (refer to Chromatic Interval Variability of Diatonic Chords), as well as a diminished quality (refer to 20240928130915-Two_Thirds_in_Triads) (Allen 2018, 100). However (Ibid):
From “7th Chords¨ in Music Theory for Electronic Music Producers
In 7th chords we can actually have four qualities of chords that emerge.
The equivalent to major and minor triads for 7th chords, i.e. major and minor 7th chords, consists in major 7th chords having 11 half-steps between the first and the seventh and minor 7th chords having 10 half-steps between the first and the seventh (Allen 2018, 101):
From “7th Chords¨ in Music Theory for Electronic Music Producers
11 half-steps make a major 7th, and 10 half-steps makes a minor 7th.
Further, if a major triad gets a major interval of a 7th, that is a major 7th chord, while if a minor triad gets a minor interval of a 7th, that is a minor 7th chord (Allen 2018, 101-102). Meanwhile, a diminished 7th chord “is still just a diminished chord like we’ve seen before, except it has a 7th on it now (a minor 7th)¨ (Allen 2018, 103). That is, a diminished 7th chord is just a diminished triad (again, refer to 20240928130915-Two_Thirds_in_Triads) with an interval of a minor interval of a 7th.
Dominant Chord Quality
The new chord quality that gets introduced by a 7th chord is that of a dominant 7th chord (Allen 2018, 104):
From “7th Chords¨ in Music Theory for Electronic Music Producers
[…] biggest difference […] is the introduction of the Dom7 chord. This is short for “dominant 7th,¨ and is a very powerful chord.
This new chord quality means our previous diatonic chord progression (refer to 20240927133630-What_is_a_Diatonic_Chord_Progression) must be modified for any chord progression built using 7th chords. Instead of the diatonic chord progression for triads, the diatonic chord progression for 7th chords is (Allen 2018, 103):
From “7th Chords¨ in Music Theory for Electronic Music Producers
Maj7 - min7 - min7 - Maj7 - Dom7 - min7 - dim7 - Maj7
Or, “M - m - m - M - dom - m - dim - M.¨ Note that this is basically the same as the diatonic chord progression for triads, save the substitution of the third instance of a major quality for the chords with a dominant quality instead (Ibid).
What constitutes a dominant 7th chord more specifically is “a major triad with a minor 7th¨ (Allen 2018, 104).
music_genre 7th_chord VII_chord key pitch chord_quality major_chord minor_chord major_triad minor_triad diminished_chord diminished_triad semitone minor_7th_chord major_7th_chord minor_VII_chord major_VII_chord minor_7th_interval major_7th_interval minor_interval major_interval dominant_7th_chord diminished_7th_chord dominant_VII_chord diminished_VII_chord interval_quality diatonic_chord_progression chord_progression diatonic_chord_progression_pattern music_theory minor_seventh major_seventh
bibliography
- “7th Chords.” In Music Theory for Electronic Music Producers: The Producer’s Guide to Harmony, Chord Progressions, and Song Structure in the MIDI Grid., 1st ed., 98. Minneapolis, MN: Slam Academy, 2018.