A funny thing about the jazz idiom. In the Blues one has the basic 12 bar pattern that all agree on and all play from. In jazz there are several standardized form patterns to jam over that several jazz standards have been derived from as well as uniquely jazz-blues progressions and then jazz has a lot of songs with the name blues in it that have nothing to do with either the blues form or jazz blues form. The composer just attached blues somewhere in the name to confuse and confound everyone. But that's jazz.
All the above being stated jazz blues is a great introduction to the world of jazz playing for the non-jazz musician hoping to branch out stylistically. Jazz has it's own unique brand of theory and using "Jazz Blues" as a starting point allows us to see this theory in action.
I've written a song called "Blues For Yous Too" based on the most common "Jazz Blues" progression. Before we get to the song. Let's look at the big picture.
Here's what the chord chart looks like.
For those not familiar with chord charts they are representations of the chord progression intended as a short hand for writing / improvising over. In many cases all a musician may receive is a chord chart or a verbal instruction referencing the progression to "jam" over.
As those familiar with blues progressions may see that while the song starts similar to the typical 12 bar blues pattern but then deviates using chord movements more associated with Jazz progressions.
Traditional 12 Bar Blues Pattern
Conventional 12 Bar Jazz-Blues Pattern
While these progressions start the same in a general sense the differ along the way.
The first thing we notice is the heavy reliance on extended chords (9's and 7's) In conventional music theory the notes derived from the primary chord form are considered the most important notes. In jazz the root 3rd and the 7th are the most important. Also in jazz (and blues) when a chord is not expressed specifically as a Major 7th chord it is a major chord with a flattened seventh. The chord is spelled/played and explained as dominant 7th chord even though the chord does not function as a the dominant (V) chord.
Note the iii7-VI7 usage in measure 8. The iii chord is a common jazz substitution for the I chord. It can be thought of and explored in more then one way. The first being that the key is retained and it is acting as a ii-vi where by the VI7 is substituted for the vi7 (major for minor substitution or parallel substitution) Or it can be considered (more commonly) as a direct modulation up a whole tone to produce a ii7-V7. In measures 9 & 10 we see the classic ii7-V7 motion and finally in measures 11 & 12 the I-VI-ii-V progression used as a turn around..
In the next installment I'll be covering melody applied to these jazz blues changes. For now in order to become more familiar with the progression I've attached a midi file of the song sans the melody. Of special note I have a few "easter eggs" in the rhythm playing for further harmonic analysis in Part Three.
Until then play the following example a few times through simply to get the feel of the chord progression.