Walking Bass - Part 3: The “Chromatic 4” Walkup
So far, we have looked at five distinct techniques for building walking bass lines from the ground up: adding the fifth, using the triad, and mixing in leading tones, passing tones, and neighbor tones. While it is possible to make many great and functional walking bass lines with just those techniques, the “chromatic 4” or “half-step walkup” is a wonderful addition to any bass player's toolbox.
This technique is found in many styles of music as a foundational pattern for moving bass lines.
Similar to leading tones, the concept is based on movement by half-step leading to a “target note”. In the case of the “chromatic 4”, a series of half steps is used to lead to a target note over the course of a full measure.
Instructions for the "chromatic 4" walkup: When a chord lasts for a whole measure in 4/4 time, play the root of the chord on beat 1 and then play three quarter notes which lead by half-step to the root of the next chord.
This concept is exemplified perfectly in the bass line to the classic Jimmy Hendrix song “Hey Joe”: 
This technique can be used any time a single chord lasts for four beats. The most important thing is to get the roots of the chords to land on beat 1.
There are other uses of the “chromatic 4” that further lessons will explore.