“It’s A C7b9 chord, and you’re playing an Effin’d natural!” the piano player is giving you the ray, which means you’re either about to get fired, or hear a lecture about how bass players don’t know jack. The lecture will be annoying, but your goal is to keep the gig, so you ask, “What should I be playing over a C7b9 anyway? I usually ignore those tiny sharps and flats in chord symbols.”
The pianist shakes his head and takes a long drag on his e-cig. In the old days, he would have put his real cigarette out on your bass. He won’t fire you—bass players are too valuable. Plus, you have a car and you drive him to gigs. But you might want to think about why he’s ranting. Does it matter which bass notes we use on a 7b9 chord? Last month, we looked at the whole–half diminished scale. Now, let’s get friendly with the half–whole diminished scale (Ex. 1).
Like the whole –half diminished scale, the half–whole diminished is an eight-note symmetrical scale. When you see the chord symbol 7b9 or 13b9, the half–whole diminished scale is a good choice (Ex. 2). At this point, let me tender a disclaimer to avoid a maelstrom of righteous indignation flooding my inbox: Chord/scale relationships offer only one of several ways to understand harmony and assist in creating, playing, and analyzing bass lines. In this Woodshed, I’m addressing chord/scale relationships.
Using the first three bars of the standard “It Could Happen to You,” we can explore the usefulness of the half–whole diminished (Ex. 3). Our focus is on the C7b9 chord in bar 2, which functions as a dominant chord leading into the Fm7 in bar 3. Bass players often like to walk up chromatically to the root of a chord. But be careful—this is where a clash can occur on a 7b9 chord. A typical bass line might look like Ex. 4: Playing the note D, which is the n9th of the C7 chord, creates a clash with the Db in the chord voicing and melody. At a fast tempo, this isn’t much of a problem; the momentum of a chromatic approach to the root F in bar 3 will disguise the sound of a D in the bass against Db in the chord in bar 2. At a medium or slow tempo, however, the sound of the n9th (D) in the bass will grate against the chord’s Db, the musical equivalent of a paper cut for one beat.
The more elegant solution uses a half–whole diminished scale, which contains the root, b9, #9, and 3rd of the C7b9 chord (Ex. 5), or a line which mirrors the b9 of the melody (Ex. 6). At a slow groove tempo, Examples 5 and 6 sound hipper. You might even get a nod of approval and some jazz eyebrows from your snarky piano player.
Example 7 shows a variation of the C7b9 sound. On the 1957 Miles Davis release Relaxin’ With the Miles Davis Quintet [Prestige], Paul Chambers chooses to go straight to the note E on the C7b9 chord, effectively making it sound like Edim7. Both C7b9 and Edim7 are found in the C half–whole diminished scale. Review last month’s Woodshed for more information about diminished chords and the whole–half diminished scale.
Example 8 shows another common way to play bar 2 of “It Could Happen to You” by using a minor IIm–V progression, in this case Gm7b5 to C7b9. The addition of the Gm7b5 simply adds more harmonic movement.
Diminished scales provide endless melodic material for soloing. Example 9 is a solo excerpt over the first five bars of “It Could Happen to You.” Note that the line in bar 2 uses the C half–whole diminished scale. In bar 4, the line uses the F# whole–half diminished scale. Next time, we’ll look at a solo étude composed entirely of diminished scales. Until then, make an effort to look at the extensions of chord symbols, and tailor your bass lines to the fit the details of the harmony and melody.
John Goldsby is teaching in July at the Aebersold Summer Jazz Workshops in Louisville, Kentucky, and the Sligo Jazz Workshop in Ireland. Introduce yourself in person, or online at johngoldsby.com.