In my November ’17 woodshed, we looked at simple triad exercses. This month, let’s grab some 7th-chord arpeggios up and down the neck. There are five main 7th-chord types: major, minor, dominant, half-diminished, and diminished. We’ll explore four of these chord types this month, and we’ll save one for next month (I’ll reveal why in a minute).
Before you pick up your bass, think about James Jamerson, who holds the title of #1 bassist of all time, as rated by the BP staff [The 100 Greatest Bass Players of All Time, February ’17]. Jamerson’s fluid use of arpeggios enhanced his incredible groove and bodacious tone. Listen to any Jamerson track, and you’ll probably hear arpeggios.
You’ll find 7th-chord arpeggios in all styles of music, so mastering them will make you a better bassist. There are several ways to understand 7th-chord construction: stacked major-and minor-3rd intervals, scale degrees, or triads with an added 7th on top.
Example 1 shows a C major 7 arpeggio (Cmaj7), followed by the notes arranged as a chord, plus the C major scale. The Cmaj7 chord is constructed with intervals of a major 3rd (marked “3” on the music, C to E), minor 3rd (“m3,” E to G), and major 3rd (G to B). Thinking in scale degrees, the C major scale generates the Cmaj7 chord from the 1st, 3rd, 5th, and 7th—the notes C, E, G, B.
The C7 chord in Ex. 2 is generated from the C dominant scale, also called the C Mixolydian mode. The intervallic construction is: 3 (C to E), m3 (E to G), and m3 (G to Bb). Notice that the difference between the Cmaj7 and the C7 is the 7th note of the scale. In the Cmaj7 chord, the 7th is B; in the C7 chord, the 7th is Bb.
Example 3 gets dark. The minor-3rd interval between the root (C) and flatted 3rd (Eb) defines the C minor sound. The intervallic construction of the Cm7 chord is: m3 (C to Eb), 3 (Eb to G), and m3 (G to Bb). The scale in Ex. 3 is C natural minor (also called C Aeolian), but the Cm7 chord also occurs in C Dorian and C Phrygian modes.
Even darker than minor, the diminished sound is the most mysterious-sounding of the five basic chords. Example 4 shows the Cdim7 arpeggio, Cdim7 chord, and the Db harmonic minor scale. Why Db harmonic minor? The chord built on the 7th degree of any harmonic minor scale is a diminished 7th. In this case, the note C is the 7th degree of the Db harmonic minor scale. The Cdim7 is built in 3rds from the root C, using the notes found in the Db harmonic minor scale: C, Eb, Gb, Bbb. The intervallic construction of the Cdim7 chord is all minor-3rd intervals: m3 (C to Eb), m3 (Eb to Gb), and m3 (Gb to Bbb). Bbb is the enharmonic equivalent of the note A. You might see either the note Bbb or the note A written in bass parts, depending on the key signature and the nerdiness factor of the person notating the chart.
Now that we’ve slogged through the theory detailing 7th-chord construction, let’s work out on the bass. Example 5 moves major-7th chords through the circle of 4ths. Play the three chords shown here, and keep traveling around the circle to play all 12 major-7th chords.
Shout out to James Jamerson! The chords in Ex. 6 move in intervals of minor 3rds: C7, Eb7, Gb7, A7. You should continue through all 12 keys by playing the same pattern over Bb7, Db7, E7, G7; and Ab7, B7, D7, F7.
Example 7 outlines minor-7th chords moving down in half-steps. Play the four arpeggios shown here, and then continue the pattern down chromatically through all 12 keys. Note: You’ll have to jump up the octave when you reach the Ebm7 arpeggio.
Example 8 demonstrates the magic of diminished chords. This exercise targets a minor-7th arpeggio, which is preceded by a diminished-7th arpeggio. Think of the pattern in two-bar groupings: Bdim7 to Cm7, Edim7 to Fm7, Adim7 to Bbm7. Once you get these six bars down, move the pattern around the circle and play all other combinations of diminished to minor chords: Ddim7 to Ebm7, Gdim7 to Abm7, Cdim7 to Dbm7, Fdim7 to Gbm7, A#dim7 to Bm7, D#dim7 to Em7, G#dim7 to Am7, C#dim7 to Dm7, and F#dim7 to Gm7.
We’ve heard how minor chords sound dark, and diminished-7th chords sound even darker. Next month, we’ll ponder the in-betweenness and functionality of the half-diminished chord (e.g., Cm7b5). Half-diminished chords sound minor-ish, but not really diminished. Also called minor 7 flat 5, the half-diminished chord is often misunderstood, and deserves special consideration in the next Woodshed.