Chords built around seventh intervals tend to be dissonant and require careful preparation and resolution in order to be use successfully in minor keys. We will explore five of these seventh chord types as part of this lesson.
We will begin our study of 7th chords by looking at the minor seven flat 5 chord. Also referred to as the James Bond chord for its frequent appearances in spy movies!
Major Seventh
Major seventh chords are four note chords composed of a major triad and an added major seventh interval, creating dissonant music that often provokes feelings of tension or emotion in music. They can also add character and flair to major or minor chords by giving them a “prettier” sound.
Learning major seventh chords requires keeping in mind that they can be formed using any note from the scale. To determine their quality (i.e. their name), simply observe how far apart are its root note from its third, fifth and seventh notes compared with what would normally make a seventh chord.
As with triads, seventh chords can be represented on the staff by stacking thirds into them – an excellent way of visualizing how they are constructed and named. Simply draw the root of your chord on the staff before adding thirds, fifths and sevenths above it; this will form a complete major seventh chord with all necessary accidentals taken into consideration.
Minor Seventh
The minor seventh chord is an integral element in many forms of music. Resembling the sound of the minor triad but with an additional flattened seventh note for more dramatic and unpredictable effect. Most commonly found as the V chord in minor key charts but can also function as an I or IV chord depending on context.
Notation for this type of seventh chord may appear daunting at first, but is actually quite straightforward. Simply add a flatted seventh to a pattern of minor triads from Intervals section for easy notation.
As with triads, seventh chords can be identified based on their root, quality and inversion (covered in the Chord Inversions chapter). To identify a seventh chord on the staff and in a major key signature. Next use note intervals to identify its quality – this works for open-spaced or crossing clef sevenths – see examples below in Table.
Dominant Seventh
A dominant seventh chord’s tension comes from its flat seventh root note, which lies one half step below the tonic note in each key. All other notes in the chord, including roots, thirds, and fifths remain constant (although fifth may be raised or lowered depending on key), with its seventh being written enharmonically as pluses or minuses for easier reading on lead sheets.
Early in rock ‘n’ roll history, dominant 7th chords were a hallmark of many iconic tunes – Carl Perkins’ classic track ‘Blue Suede Shoes’ made use of D7 and E7 chords to produce its foot-tapping rhythm.
One approach for quickly creating chords of this sort is taking an existing major triad and adding a minor seventh above it, such as in this example where C major triad with C-E-G chord is modified into D7 by adding B since minor scale seventh interval is one step lower than major scale seventh interval.
Half-Diminished Seventh
Building a seventh chord gives you access to eight distinct qualities. Each quality follows the pattern of major scale with some subtle modifications. To determine its quality, draw the root on a staff and add any necessary key signature accidentals for that scale; then think or write out (imagine) or visualize (write out) a triad with its third, fifth and seventh notes above the root; these notes form your seventh chord.
An A half-diminished seventh chord’s root note, D, forms its triad: A-C-E; when altered by switching out its perfect fifth for an diminished fifth, its status changes to minor seventh.
This chord, known as a semi-diminished seventh chord (m7b5), shares many of the same tonal functions with fully diminished sevenths, yet sounds somewhat less harsh due to not suspending third. This chord can help create tension by producing sound changes with each note played on it.