Rhythm Changes in Bb

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Seth Rosen has played mandolin for nearly 30 years. A multi-instrumentalist (guitar, bass and violin too) he has performed with a wide range of performers including: Blues legend Howard Armstrong, Swing greats Bross Townsend and Rusty Mason, Songwriter Si Kahn and Western musicians Liz Masterson and Sean Blackburn. He currently plays in two northeast Ohio Bands: Crazy Rhythm playing swing and western swing, and The Suspenders! playing jump blues & roots rock. He has been on the staff of the Augusta Heritage Center's "Swing Week" for six of the past eight years as both a dance musician and a swing mandolin instructor.


In this lesson, we take a look at "Rhythm Changes" in Bb, the chord changes that come from the song "I Got Rhythm" by George Gershwin. We'll learn some concepts about chord substitution and the "folk process" as it effects a jazz standard.

As with Lesson I, I have not included any chord diagrams. This site has lots of chord diagram in general and a few for Rhythm changes in particular. Also, figuring out chord voicing is an important part of the lesson. Most of the chords can be voiced using 3 note moveable chords (ie closed positions).

If you have questions, post them on the message board of the Mandolin Cafe and I (or the other knowledgeable players that gather here) can answer them.

Where to start this lesson was an interesting question. This site already has 3 lessons about Rhythm Changes and none of them use the same set of chords! Why so much variation? Some of the difference is chord substitution, but the rest is the process of evolution that changes music over time. I tried to start with what I believe is the "original" melody and chords to Gershwin's I Got Rhythm.

Notice first off that this is a 34 bar song rather than a 32 bar format. It has the AABA form of a 32 bar tune, but the last A has a little turn around tag.

The chords are pretty straight forward and contain a number of repeating patterns. Repeating sections like this are often good places for substitute chords.

Version two has a series of substitute chords that stylists of old jazz (eg pre swing big bands) would likely use.

The first substitution comes in measure three, where we replace the Gm7 with a Bbdim (NOTE: NOT a Bdim, see version 3 for that one). This works because a Bbdim is very close to Gm7b5 (Db being the b5 in G and the b3 in Bb) so the Idim chord is used instead of the VIm7th. This occurs twice more on this chart and could really be used where ever the Gm7 is.

The other substitutions on version 2 are using 9ths for 7ths in the second measure of the chords in the bridge. While, as we learned in lesson one, 9ths can always replace 7ths; the D9th is particularly appropriate because of the E (the 9th) in the melody.

In the last measure of the bridge we substitute Faug for F7. As we saw in lesson I, substituting an augmented V chord for the V is the most powerful 'turn around' know to man...this is why it works in this context. Play it a couple of times each way, you'll see what I mean.

Version 3 is a much more common way that you'll hear I Got Rhythm played today. This version is more a result of the evolution of the tune than about chord theory.

First of all, note that the song has now become a 32 bar tune, the extra two measure are only used as tag the last time through. My completely unsubstantiated guess is that this happened on the bandstand where head arrangements (ie not written out) required common patterns. Most of the KC early swing bands (Moten, Basie) were head arrangement bands at first.

The next big change is that the Bbdim has become a Bdim. This substitution works because it's built around a great moving bass line:

Bb Bb B B/ C C F F/.

I don't know where that got started but if that cat had patented it he'd be a rich man. This substitution blew the old chords away and became the standard change. You might want to select chord voicing that contain this chromatic movement.

The other change in the A part is to substitute Bb7 for the Gm7 in measures 5, 13 & 29. While this doesn't seem to make sense (Ab over G), the change I to I7 leads your ear to the IV that comes next, more than the I to VIm7 does (try this both ways to hear the difference). That change became very common as well.

While the bridge is often played as above in version 2, some additional substitutions are possible. The Ddim works to create some tension through the use of the tritone-- b5-- and only works because it resolves in the D9. The same principle in the opposite direction explains the Gm7 Daug which have a Bb (instead of the B of G7) that resolves to Dm7 (a substitute for G7)...this uses the sound of the #5 (Bb in the Daug) to the 5 (A in Dmin). The concept in these substitutions is that of neighboring tones...playing the neighbor (b5 and #5 respectively) then resolving to the "normal" chord tone. While I don't usually play these chords when playing rhythm, I like to use these diminished & augmented arpeggios in a solo.

The Cdim for C is similar to substituting the relative minor (Am for C) since we know that Cdim is much like Am7b5.

The chord changes in version 3 or other similar changes were so compelling that hundreds of tunes were written utilizing them. I think this is because they are so much fun to jam over...many of the tunes that use these changes are "jam tunes" with a simple "head" and lots of room to blow. My favorite of these is "Lester Leaps In", by the great tenor sax man Lester Young. I use the exact same changes as I did in version 3 of of Rhythm over this melody. Note that there is a pick-up measure before measure 1. Also note that there is no melody for the bridge, just improvisation.

You also might one to compare these charts to the other versions of "Rhythm" that you'll find on this site. Many of those examples use some nice chord voicings too.

Finally...what do you play when you're on the bandstand or at a jam session and someones calls a tune that uses Rhythm changes??

Sometimes you ask: "I#dim , I dim or VIm7 ?"

Sometimes you hang back and listen the first time through......

Sometimes you just know!

Good luck... and feel free to post any questions on the message board under jazz, swing etc.