The Secret of Subtractive Rhythms

Great improvisers know that no matter how melodically or harmonically sophisticated their solos may get, there has to be a good rhythmic flow happening for things to groove and ultimately move the audience. In this lesson, we’ll explore a fun way of using what I call “subtractive rhythms.” First we’ll create a steady stream of eighth-notes over a common 12-bar blues progression, and then we’ll learn how to use an “eraser” to create a flowing, rhythmically happening jazz solo.

Jazz players often practice steady eighth-notes over tunes to internalize the overall structure, and absorb the melodic or harmonic relationships. The melodic shapes often come from solos they’ve heard or from patterns they practice. This kind of practice can really improve the internal flow of musical information and deepen the musical well from which they draw ideas. The second part of this ability is to respect the space between the notes, as well.

A fun, three-step musical game that can jump-start your process resembles a childhood art experiment where you use crayons to fill an entire page with different colors, then cover everything up with the black crayon, and finally etch shapes into the top layer to reveal magically colorful pictures. This is, of course, an exercise to demonstrate the importance of negative space in all art forms.

Translating that process into musical terms will mean filling up a piece of staff paper with a steady stream of eighth-notes, removing some notes to create hip rhythms, and crafting what’s left into something musical to practice.

Step 1: Discovering Your Licks
One of the benefits of writing out a practice solo is that it gives you an idea of what your licks or go-to melodic patterns tend to be. This might prompt you to explore new patterns and insert something different whenever you begin to repeat yourself. Now, the ear does enjoy hearing a certain amount of repetition, but your job is to decide when to change things up. In Ex. 1 I’ve written out a solo over a typical jazz-blues progression in the key of F.

Click here for Ex. 1

The chromatic scale plays an important role in helping jazz improvisers arrive at key anchor points in a line at just the right time. A good example of this can be found in measure seven. The goal is to create a delay in moving to a strong chord tone, in this case the 3 (A). Instead of heading right from Bb to A, we insert two chromatic approach tones (G and G#) to push the A on to a strong beat. More chromaticism is used in measure nine where we approach two different chord tones (Bb and G) with a pair of chromatic approach tones. Again, the goal here was to have the diatonic scale tones land on downbeats. Note the 5 (D) is inserted as an anchor point between the two melodic groupings. Everything wraps up with a chromatic scale all the way down from the 6 of C7 (A) to the root of F7.

Tritone Substitution
In its most basic form, a tritone substitution is simply overlaying a dominant chord with another dominant chord that’s a tritone (seven frets) away. For example, you could replace a C7 with a Gb7. Or an F7 with a B7. Also, it works for single-note lines as well as comping.

Arguably, the best way to use these substitutions is to avoid hitting the listener over the head with it. This can be achieved by starting your line on a note that both chords share, known as a common tone. The line in measure 10 over the C+7 chord is simply me visualizing a Gb Mixolydian (Gb–Ab–Bb–Cb–Db–Eb–Fb). Because the E (or Fb) can be considered the 3 of C7, I chose that as my starting point. By choosing this common tone, the ear hears this line more as a colorful C7alt. chord than an obvious tritone substitute. Superimposing other chords in lines is a good way to open up your color palette and break out of your usual set of licks.

Octave Displacement
One really useful tool to change things up is what is generally known as “octave displacement,” or, in the words of bebop master Barry Harris, “pivoting.” This is where you simply jump an octave in either direction and then continue your line.

Let’s revisit measure seven. Notice how the line would have logically continued downward from the 5 (C) to the 4 (Bb) then chromatically back up from the 2 (G) to the 3 (A). Moving the Bb up an octave quickly adds brightness to the line. Conversely, in measure 11 we jump from an Eb to an F# to create a mellowing effect over D7b9.

Step 2: Get Some Rhythm
One way to add rhythm to your eighth-note practice solo is to simply tap out or sing rhythms that sound good to you, and then go about erasing notes to match those rhythms. Make sure to save a copy of your original solo, just in case! This won’t always sound 100-percent natural, so you might need to make a few minor adjustments to improve the flow. You’ll notice that a lot of the lines in Ex. 2 still begin on downbeats, which can sound a little stiff in a jazz context. And your ear might prefer a sustained note here and there.

Click here for Ex. 2

Here’s the fun part where you can really get creative with your ideas. If you first tap or sing the rhythms in Ex. 3, you’ll see and hear the end result of this process. The overall rhythmic scheme in this example is probably closer to what you might expect to hear in a jazz solo than in Ex. 2. Things pop a bit more and there’s more variety—including triplets and some sustained notes. Notice how much more the phrase in measure three swings by inserting an eighth-note pickup before the downbeat and then moving everything on the other side of it up by an eighth-note. This type of simple editing can be found throughout the example. Sometimes you’ll come up with entirely new ideas during the course of this process. For example, take measure nine: Here, we create a classic altered-dominant sound by transposing a modified version of the Gm7 idea up a minor third, starting on beat 3.

Click here for Ex. 3

One last trick to note is in measure 12. Over the first triplet I’m playing a descending Bb major triad in 1st inversion (Bb–F–D). When we move to the C7, I simply move that whole shape down a half-step to hit the 13 (A), 3 (E), and b9 (Db) for a wicked-cool altered sound.

A final suggestion is to copy licks and patterns you like into a “hot licks” book that you keep accessible. Then you can create exercises where you take those patterns through a logical process, such as playing in all 12 keys or by starting the pattern on each step of a particular scale. Remember to not get caught in the eighth-note rut that traps many jazz players, no matter how long they’ve been playing. Think like a drummer and remember that groove trumps all!