We covered a standard 12 bar blues in the last issue. In a jazz 12 bar blues, other chords are included in addition to the I, IV and V chords. Let's start by comparing chord progressions of a standard 12 bar blues to a common 12 bar jazz blues. Example one demonstrates the standard 12 bar blues.

Example two below demonstrates a 12 bar jazz blues progression.

The 1st bar is the same in each progression, the G7 or the tonic. The 2nd bar is a change, often called a quick IV (C7), which is common to blues and jazz blues progressions. The 3rd bar is the same in both progressions. The 4th bar of the jazz blues is called a ii-V progression (Dm7-G7), the building block of jazz music. The ii is minor and written in lower case Roman numerals, whereas the V is dominant and written in uppercase numerals. The ii-V progression is relative to the IV chord, not the I chord. In other words, the Dm7 is the ii of the C7 chord and the G7 is the V of the C7 chord. The ii-V progression leads to and resolves on the C7 chord. It is a way of harmonically moving from the I chord to the IV chord. The possible notes played over the Dm7 are exactly the same as the notes played over the C7 except the starting place is one whole step higher on the Dm chord, consequently changing the 3rds and 7ths. It is analogous to playing 3rd position over the Dm7 and straight harp over the C7. The reason this harmonic movement works so well is because of the relationship between the pitches of the 3rds and 7ths in each chord. They are right next to each other or 1/2 step apart:


Notice the 3rd of the Dm7 is the same note as the 7th of the G7. Try holding an F over both chords. This creates a sense of melodic movement even though you're sitting on one note because the chords are changing beneath the note. The 7th of the Dm7 is 1/2 step higher than the 3rd of the G7. Try playing the C over the Dm7 and then resolving to the B over the G7 chord. The 3rds and 7ths of the G7 and C7, again, are 1/2 step apart. The chords which have the most potential for altering and playing substitutions over are the dominant chords. You can play any note you want over a dominant chord as long as you land in the right place. In other words, it is possible to play altered notes, such as chromatic runs, over the dominant chords to create tension if you then create resolution in the following chord. A lick that illustrates this over our ii-V-I progression to the C7 chord is this:

This phrase outlines the harmonic movement of the ii-V-I chord progression by using the 3rds and 7ths to create tension and resolution. It starts with the Dm7 arpeggio up to the 7th. You'll notice an unusual note over the G7 chord, an A-flat. This is an altered flat-9 and creates tension. Then, the phrase moves to the root and 7th of the G7, finally resolving on the 3rd of the C7. The 6th bar of the jazz blues is a C# diminished chord. The diminished chord is a stack of minor 3rds, C#, E, G, Bb. The arpeggio is exactly the same as the C7 arpeggio, except the 1st note is 1/2 step higher. If you have learned the C7 arpeggio (1+ 2+ 2 3') just change the 1st note to 1' and you'll have the C# diminished arpeggio. This chord leads back to the I chord, G7. In bars 8 through 12 of the jazz blues there is a iii-VI-ii-V progression played twice. In this case, the iii-VI-ii-V progression is relative to the tonic or the G7 chord at the top of the progression. The iii-VI-ii-V progression is really a series of two ii-V's. It is just a repeat of the same harmonic movement. Let's again compare the 3rds and 7ths in the iii-VI-ii-V progression:


Again, notice the 3rds and 7ths of each chord are either the same note or only 1/2 step apart. Initially, all of this theory and #s may be overwhelming. The real meaning of the theory is identifying how the pitches work together. Start by playing the roots of each chord over a jam track. Continue up and down the arpeggios as we did in the last issue over the 12 bar jazz blues. Eventually, the sounds will become ingrained in your head and the melodies will make more sense in your improvisation. Example 4 below shows the basic arpeggio for each chord.

Overbend Chart
Bottom holes are draw. Top holes are blow. Colored boxes are overbends.