The concept I am about to show you is sometimes called Guide Tones or Voice-Leading.
And it works really well over any chord progression, simple, complex, or random! And you can use this for your bass solos and walking bass lines!
Here's why this works: Any chord progression, wether it's simple, complex, or random, has inner voice movement.
Inner voice movement occurs when a chord tone of a chord is followed by a nearby chord tone of the next chord.
Typically, the closest chord tone is a whole-step or half-step away (either up or down).
In some occasions, the closest chord tone is either the same chord tone (the chord tone doesn't change), or a chord tone that is a third interval away (either up or down).
Once you uncover an inner voice movement, you'll have a simple melody can be used as a framework for crafting your bass lines.
Using this framework will give your bass lines an overall direction, and making them sound more cohesive.
So here's how melodic direction is created using this concept.
The following steps will outline the best way to practice crafting bass lines with strong melodic direction over any chord progression.
I recommend practicing these steps a lot, until you are able to start hearing inner voice movement on your own.
Here's 4 steps for practicing voice-leading to create melodic direction with your bass solos or walking bass lines:
So for example, let's look at this chord progression: Bbmaj7, G7, Cmin7, F7
Now, write out each chord tone for each of these chords.
Bbmaj7 has these chord tones: Bb, D, F, A
G7 has these chord tones: G, B, D, F
Cmin7 has these chord tones: C, Eb, G, Bb
F7 has these chord tones: F, A, C, Eb
Let's say you were to start your melodic line on the note D.
When you arrive at the G7 chord, your melody can then start on the note B.
Then, when you arrive at the Cmin7 chord, your melody can start on the note Bb.
Finally, when you arrive at the F7 chord, your melody can start on the note A.
So your inner voice melody is: D, B, Bb, A. This is a descending inner voice melody.
Another one you can try is ascending: Bb, B, C, Eb
You can also try staying in a limited range, where the inner voice movement stays put, like this: F, F, Eb, Eb
Visualize your fretboard better and create lines from chord voicings using guide tones. Although this book is intended for guitarists, these concepts can easily be applied for your bass solos and walking bass lines!
The Changes - Sid Jacobs: Guide Tones for Jazz chords, Lines and Comping for Guitar
(Select any below that you agree with)