Variations and harmonizations of the blues

Example #1

At this point we can see how to harmonize a blues chorus, harmonically enriching it with some complex solutions, that sometimes gives us jazz sounds, and other times rock. We will generalize these terms, given their numerous variations.
We will start with a basic harmonization that uses standard harmonic communication rhythms between one degree of the chorus and another. Look at the underlying harmonic base, which you can also listen to to help you better understand it.

Analyzing the succession of chords, we see that the II° - V° rhythms preclude a change of harmonic section, as in the case of bars 4 and 8, while using the F7 on the second bar serves mainly to create a typical blues sound, actually given by the I° - IV° passage, in our case C7 (first bar) and F7 (second bar).
In the sixth bar we see one of the more common harmonic substitutions used. The F7 in the fifth bar is followed by a chord lowered by a semitone, which is F#dim. This characterizes a chromatic movement on the basses, intended as F, F# and G, where the final G should be the bass to the tonal chord C7 in the seventh bar.
Finally we have the turn around on the last two measures. This term is used to identify a harmonic movement of chords based on the fall of dominants, movements that vary depending on the situation. In these two bars the turn around is made up of I° - VI° - II° - V°, which is C7 - A7 - D7 - G7.

Example #2

This is more of a pop-rock situation. As you can see the harmony of the chords is simplified to make room for some typical rock melodies. In many cases the use of bichords or power-chords in necessary, which allow the use of pentatonic scales, as well as major tonal scales, relating mostly to the C note. You need to make a precise choice on the use of the scales, because its possible, for instance, to play in the pentatonic of Cm to have a more bluesy (and rock) sound, but also on the major scale, which is typical of a pop context. The only point of harmonic change is found in bars 5 and 9, where the Bb appears. At this point melodically we can play in F (bars 5, 6, 9 and 10), then immediately return to C.

Harmonic transposition

Harmonic research in jazz has always been at the base of improvisation. The blues are expressed on a melodic and harmonic level, differentiating itself from the classical three chord base. Therefore the harmonic variations are endless.
In example #1 we saw a first harmonization based on this procedure. In the next page you will find a series of blues examples, each of which has a different harmonization. To make things easier they are written in one scale, but you should try them in all the scales. Remember that in a blues and rock context the most commonly used scales are A, E, G, C and D, while for jazz it is more common to find F, Bb, Eb and Ab. The difference is due to the fact that jazz normally uses wind instruments that prefer these scales.
In the chart below, we can see with what critera the notes are transposed. In the example we use the mixolidian C scale (upper line), the most common in standard blues, carrying it to mixolidian E (lower line), and therefore a third major above. Remember that all the ideas used this particular situation, can be found in the theory section. Observing the chart you can see how every note is carried a third major above.

To transpose a sequence of chords you follow the same reasoning. Depending on the interval, just transpose each chord into the new scale. Here is how to transpose a blues in C one fourth above, or from C to F. Remember that the % symbol indicates the repetition of the preceding bar.

Or from the scale of C to A.

Now that we have analyzed the fundamental concepts on the harmonic transposition, you can look at a series of harmonic variations in a twelve bar blues chorus.