When you play the previous example, you will find that the diatonic method for approach tones works fine and is a viable option. After repeated hearings, you may begin to feel that this method of approach sounds rather bland much of the time. This is because the diatonic approach method often results in whole step resolutions between approach note and target note. In the previous example, there was only one instance of a half step resolution (from the approach note "A" in the first measure to the target note "Bb"), and many people feel that a half step resolution tends to sound stronger than a whole step resolution. If your ear is telling you the same thing, then it is time to examine the Chromatic method of approach.
When you use the Chromatic approach method, it is of no concern whatsoever whether the approach note is a part of the current chord scale or not. All that matters is that the resolution from approach note to target note is by half step from either below or above. If we modify the previous example from diatonic approach to chromatic approach, it will look like this:
At this stage, the Chromatic approach method is clearly the easier to implement of the two, since no real knowledge of chord scale construction is required to use it. But don't be fooled: While you can get by with this method for a "2 feel" bassline, you will need to become intimately acquainted with jazz chord scales in order to construct a walking bass line - our next project.
A typical walking bass line consists of a string of quarter notes in 4/4 time. When there are two chords per bar, we can construct a walking line by simply using the chromatic approach method to fill the spaces between target notes, as follows:
The line constructed by using this method is not only perfectly acceptable, but is also an extremely typical example of a walking line in a two-chords-per-bar context.
Building a walking line gets a bit more complicated when there is only one chord per bar. Beat 1 of each measure will be filled with target notes, and beat 4 will be taken up by approach notes. This leaves beats 2 and 3 of each measure open, as follows:
The spaces in a walking line like this one may be filled in one of two ways: by using chord tones, or by using scale tones. We'll look at how to use chord tones first.
The term chord tone refers to any of the following parts of the scale: Root, 3rd, 5th, or 7th. For example, in the F7 scale, the chord tones would be F (root), A (third), C (5th), and Eb (7th). To use these chord tones (abbreviated "C") to fill the holes in the above line, the main concern is to arrange the chord tones in an order that leads toward the next target tone. Then choose an approach tone that leads into the target tone by stepwise motion.
Using only the techniques discussed so far, you now have the tools to build basic "2 feel" and walking bass lines. We'll discuss the use of scale tones and how to combine them with chord tones in the next chapter. Until then, spend some time constructing lines with the basic tools you have so far: target notes, approach notes, and chord tones. Good luck!