A common rite of passage for jazz players is learning to play on 'rhythm changes',
variations on the chords to Gershwin's song "I Got Rhythm", written in 1930.
First, let's look at the harmony in its most basic form.
Then we'll examine some variations frequently used by jazz musicians.
In the second part of this series, we'll check out some ideas
for improvising lines on the changes...Basic Rhythm Changes
The chords in their simplest form look something like this:
Bb \ Gm \ | Cm \ F7 \ |Bb \ Gm \ | Cm \ F7 \ |
Bb \ Bb7 \ | Eb \ Ebm \ | Bb \ F7 \ | Bb \ \ \ |
Bb \ Gm \ | Cm \ F7 \ |Bb \ Gm \ | Cm \ F7 \ |
Bb \ Bb7 \ | Eb \ Ebm \ | Bb \ F7 \ | Bb \ \ \ ||
bridge:
D7 \ \ \ | \ \ \ \ | G7 \ \ \ | \ \ \ \ |
C7 \ \ \ | \ \ \ \ | F7 \ \ \ | \ \ \ \ ||Bb \ Gm \ | Cm \ F7 \ |Bb \ Gm \ | Cm \ F7 \ |
Bb \ Bb7 \ | Eb \ Ebm \ | Bb \ F7 \ | Bb \ \ \ ||
Note that the form is standard 32-bar (A-A-B-A) song form.
(The original version had a two-bar tag that is almost never used by jazz players.)
The A Section
The first four measures of each 'A' section are a very diatonic
I - vi - ii - V progression; jazz players soon began experimenting
with ways to make this sequence more interesting to play on.
One common swing-era variation had A sections like this:
Bb \ Bb7/D \ | Eb \ Edim \ | Bb/F \ Dbdim \ | Cm \ F7 \ |
Bb \ Bb7/D \ | Eb \ Ebm \ | Bb/F \ F7 \ | Bb \ \ \ ||Another popular version went this way:
Bb \ Bdim \ | Cm \ C#dim \ | Dm7 \ G7 \ | Cm \ F7 \ |
Bb \ Bb7 \ | Eb \ Edim \ | Bb/F \ F7 \ | Bb \ \ \ ||
The Bdim and C#dim chords act as substitutes for G7b9 and A7b9;
giving us more harmonic tension and color as they pull to Cm and Dm, respectively.As swing began giving way to bop, the A section started looking more like this:
Bbmaj7 \ G7b9 \ | Cm7 \ C#dim \ | Dm7 \ G7b9 \ | Cm7 \ F7 \ |
Fm7 \ Bb7 \ | Ebmaj7 \ Ab7(#11) \ | Dm7 \ G7b9 \ | Cm7 \ F7b9 \ ||
The bop players liked to extend the chords out to 7ths and 9ths.
They also liked to alter functional (resolving) dominants.
Notice also the action in bars 5 and 6; we're milking a little more motion out of the tune
by putting the Fm7 in to act as a ii to the Bb7.
The Ab7(#11) is a substitute for Ebm from the basic changes.A more 'modern' version uses tritone substitution for some of the VI and V chords:
Bbmaj7 \ G7b9 \ | Cm7 \ F7b9 \ | Dm7 \ Db9 \ | Cm7 \ B9 \ |
Bb11 \ Bb7b9 \ | Ebmaj7 \ Ab7 \ | Dm7 \ Db9 \ | Cm7 \ B9 \ ||As you can see, there are quite a few ways to harmonize the A section!
That's why jazz players like playing on rhythm changes;
the harmony provides lots of options for an improvisor.
These are just a few of the possibilities, but that's plenty for now.
Let's look at the bridge...Rhythm Bridges
The bridge follows a pattern my old theory teacher used to call a
'secondary dominant sequence'.
In simpler terms, it's a sort of daisy-chain made from dominant 7th chords.
Each 7th chord acts as a V chord for the chord which follows it,
setting up a prolonged tonal 'pull' which eventually leaves us on the V of Bb,
poised to return to the final A section.
D7 \ \ \ | \ \ \ \ | G7 \ \ \ | \ \ \ \ |C7 \ \ \ | \ \ \ \ |F7 \ \ \ | \ \ \ \ ||The boppers liked to put a ii chord before each V chord in the pattern:
Am7 \ \ \ | D7 \ \ \ | Dm7 \ \ \ | G7 \ \ \ | Gm7 \ \ \ | C7 \ \ \ | Cm7 \ \ \ |F7 \ \ \ ||
This kind of sequence, in which each V chord becomes the ii chord of the next V,
is commonly called a "back-cycle" progression by jazzers.Using tritone substitution, a bridge like this could be built:
D7 \ \ \ | \ \ \ \ | Db7 \ \ \ | \ \ \ \ | C7 \ \ \ | \ \ \ \ | B7 \ \ \ | \ \ \ \ ||
or this:
Am7 \ \ \ | D9 \ \ \ | Abm7 \ \ \ | Db9 \ \ \ | Gm7 \ \ \ | C9 \ \ \ | Gbm7 \ \ \ | B9 \ \ \ ||
or this:
Whee!! Another less common rhythm bridge should be mentioned:
Bb7 \ \ \ | \ \ \ \ | Ab7 \ \ \ | \ \ \ \ | Gb7 \ \ \ | \ \ \ \ | F7 \ \ \ | \ \ \ \ ||
This one turns up in some swing tunes ("Rough Riders" and "Heavy Artillery", for example)
as well as in the occasional bop head.Okay, so now we've got a pretty good handle on the changes.
Now, what to play over them?