Can you offer me any good approaches to take regarding walking bass lines?
What a walking bass line does is to provide a living metronome for other notes being played in a piece of music.
Creating a walking bass line is like solving a puzzle. Fortunately, a large part of the solution is automatically worked out for you, because on the beat that a chord symbol appears, you should play the root of that chord (which is to say, the same letter of the alphabet as the chord symbol) or, if it’s a slash chord notation, the note on the right side of the slash. The part of the puzzle that you have to work out is to find notes to fill in the beats between the chord symbols.
The simplest solution is just to play repeated notes on the root of the chord for as many beats as the chord lasts until the next chord. This actually works because it fulfills the metronomic function of the bass line. You could start out this way.
But then, the bass line isn’t really walking yet. “Walking” means that it is traveling from one place to another. The question then is how to travel between the roots of successive chords. The answer is to move by steps (scales) or by skips (arpeggios) or a combination of both. What follows will illustrate specifically how to do that.
There are finite possibilities for root movement between pairs of letters of the alphabet. For example, using the note A as the starting point, it could be followed by another A (repeated note, up an octave, or down an octave), or by B (up a second or down a seventh), or by C (up a third or down a sixth), or by D (up a fourth or down a fifth), or by E (up a fifth or down a fourth), or by F (up a sixth or down a third), or by G (up a seventh or down a second). The addition of sharps or flats to these doesn’t fundamentally change the puzzle.
Out of all of these possibilities, the most frequently encountered is a root movement of descending fifths (or ascending fourths, which yields the same alphabet letters). The seven alphabet letters in the order of descending fifths (ascending fourths) starting with A are: A, D, G, C, F, B, E.
Four of these in sequence form a word that is easy to remember—BEAD—and you can create your own mnemonic for the following GCF. Just open a fake book to any random page and you will almost always find some segment of the BEADGCF sequence. I am fond of saying that this accounts for about 85% of jazz tunes.
In 4/4 time, it is common for chords to last two beats or four beats, and sometimes eight beats, and occasionally one beat. Now all you need is a system for walking in two, four, sometimes eight, and occasionally one beat between the pairs A and A, A and B, A and C, A and D, A and E, A and F, and A and G, and all of their transpositions.
The easiest solution is when the chord lasts only one beat. In this case, you just play the root of that chord and then the root of the next chord. There are no beats to fill in between the chords. That takes care of that.
Another very easy solution is when the chord lasts eight beats. In this case, play an ascending or descending scale that starts and ends on the chord root. For example, if you have an Amaj7 chord for eight beats, you would play ascending A, B, C#, D (barline), E, F#, G#, A or descending A, G#, F#, E (barline), D, C#, B, A. The fact that the downbeat after the barline is a letter of the alphabet that doesn’t match the chord symbol is accepted as an exception to the rule.
When the chord lasts two beats, that is fairly easy because you only have to come up with one note between the chord roots. A solution is to approach the next chord root by a step, preferably a half step, either above or below it.
For example, let’s take the frequently encountered descending fifths (ascending fourths) root movement. If the chord progression is A to D in half notes, approaching by a half step above the next chord root would be either A up to Eb and down to D, or A down to Eb and down to D. In either direction, this creates the interval of a tritone (A to Eb). This is a commonly-used solution when the first chord is a dominant seventh, diminished seventh, or half-diminished seventh.
A solution approaching by a half step below the next chord root would be A up to C# and up to D, or A down to C# and up to D. This is a commonly-used solution when the first chord is either a major seventh or dominant seventh. An approach by a whole step either above or below the next chord root works best when the first chord is a minor seventh.
Now all you need is a system for getting from A to A in four beats; from A to B in four beats; from A to C in four beats; and the same for A to D, A to E, A to F, and A to G.
Let’s take an example. In the tune “Autumn Leaves” with a key signature of one sharp, the first seven chords are Amin7, D7, Gmaj7, Cmaj7, F#min(b5), B7, and Emin7. Notice that these are the seven alphabet letters, starting with A, in the order of descending fifths (ascending fourths).
Each chord lasts for four beats. On beat one of each measure, you would play the root of the chord. Now there are three beats remaining in each measure and it’s time to solve the puzzle.
The descending fifths progression in four beats is the most straightforward walking bass solution. Play the root of the chord on beat one and then to go down the scale on beats two, three, and four, arriving another step later on beat one of the next measure. So, Amin7 to D7 would be A, G, F#, E (barline), D.
The customary solution for walking an ascending fourth root movement in four beats is to play the root of the chord on beat one and then to go up a whole step and two half steps, no matter whether the chord is major or minor in its basic quality. So, Amin7 to D7 would be A, B, C, C# (barline), D.
These two patterns will get you through about 85% of jazz because of the ubiquity of the descending fifths (ascending fourths) root movements.
Another easy solution for when the chord lasts four beats is to play only the chord tones as an arpeggio. The chord A (add accidentals according to the chord quality) would be ascending A, C, E, A or descending A, E, C, A; and with the seventh would be ascending A, C, E, G or descending A, G, E, C. Then you proceed to the root of the next chord.
If the root of the next chord is not a step away from the note on the fourth beat, there will be some potentially inelegant skipping to the next root. Again, this is acceptable because the bass line not only maintains its metronomic function but it also travels from one root to the next. However, you can create solutions that are more elegant by combining steps and skips.
Here are some possible solutions for the other root movements in four beats (add accidentals according to the chord quality), but you may invent many others:
A to A (repeated note): A, B, C, B (barline), A
A to A (up an octave): A, B, C, E (barline), A
A to A (down an octave): A, E, C, B (barline), A
A up to B: A, E, C, A (barline), B
A down to B: A, E, D, C (barline), B
A up to C: A, B, C, D (barline), C
A down to C: A, E, A, B (barline), C
A up to E: A, B, C, D (barline), E
A down to E: A, E, C, D (barline), E
A up to F: A, C, D, E (barline), F
A down to F: A, G, F, E (barline), F
A up to G: A, C, E, A (barline), G
A down to G: A, B, C, A (barline), G
There are a couple of other artistic considerations when constructing a walking bass line. One is to go in contrary motion to the direction of the melody when possible. For example, in “Autumn Leaves” with a key signature of one sharp, the D7 measure has the melody notes D, E, and F# ascending on beats 2, 3, and 4. If you use the ascending walking bass solution for ascending fourths in four beats, you have the notes D, E, F, and F# on beats 1, 2, 3, and 4. The E in the bass is dissonant with the D in the melody, and same for the F in the bass with the E in the melody. Simply using the descending fifths solution instead of D, C, B, A will completely avoid this problem. Besides, contrary motion has a more balanced effect overall, even if dissonances don’t exist between the bass line and the melody line.
Another is to animate the bass line occasionally with some swing eighth notes. The easiest implementation of this is to repeat any of the bass notes on any beat of the measure, doing this once per measure. Using “Autumn Leaves” as an example, the Amin7 measure in the ascending pattern could be A-A (swing eighths), B, C, C#; or A, B-B, C, C#; or A, B, C-C, C#; or A, B, C, C#-C#.
Another is to alternate ascending and descending motion in the bass line so that it doesn’t travel too far in one direction.
Another is to keep in mind the approach-the-next-root-by-a-half-step rule even with chords lasting more than two beats.
If you are playing a walking bass line on an instrument other than a double bass or a bass guitar, then it is important to play the line in the actual range of a double bass or bass guitar. Many pianists let the line come too close to the center of the keyboard, for example.
As you develop sophistication in your walking bass lines, you may not choose every time to play the root of the chord on the beat that a chord symbol appears. This will work as long as you clearly define the identity of the chord with your choice of notes. A walking bass line in four beats for the chord A (add accidentals according to the chord quality) could appear as B, A, C, E; or C, D, E, A; or C, E, A, C, to give just three examples.
The last piece of advice is that you should listen to bass players and take inventory of what they are doing. If possible, talk to bass players about how they create their own walking bass lines.