treble clef
Notes on Notes
A Mystery Passenger in the Caravan

  1. The Diminished Passing Chord

  2. Caravan - A section

  3. The Mystery Passenger unveiled

  4. Improvisation

  5. Modes of the 8-note Symmetric scales

  6. Caravan - Bridge

  7. Downloading Bay

    Notes on Notes - Jazclass Links

Down - Top - Jazclass Links)

CA 1.1 - The Diminished Passing Chord

The diminished 7th chord (o7) consists of 4 notes which are spaced at equal intervals of 3 semitones ( one 'minor 3rd'). The diminished 7th chord is therefore a symmetric chord.
Here is for example the Eo7 chord.

Audio 1

As a consequence of this equal spacing of the chord tones there is no unique root tone for the chord. Each chord tone can be the root of its own diminished chord, and use the remaining three notes as its other chord tones.
The chord tones for Eo7 for example also make up the Go7, Bbo7 and Dbo7 chords.

  • Eo7 = E - G - Bb - Db

  • Go7 = G - Bb - Db - E

  • Bbo7 = Bb - Db - E - G

  • Dbo7 = Db - E - G - Bb
Audio 2

This uncertainty as to which chord tone is the root of the chord gives the diminished chord a rather ambiguous, floating quality. It defines no clear key or tonal centre.

In music harmony this ambiguous nature has been exploited to the full by using the diminished chord predominantly as a passing chord, connecting one chord in a progression to the next, or to harmonise non-chord tones in a melody.
Trad Jazz standards (and other popular songs from that era) in particular are full of diminished passing chords.

Down - Up - Top - Jazclass Links)

CA 1.2 - Caravan : A section

Now have let us have a look at this song.
Caravan is a medium tempo Latin standard in 'Cut Time' (2/2) by Duke Ellington.
The song is in the key of F minor. It is 64 bars long and has an A A B A format. Each section consists of 16 bars.

Here is the A section.

Audio 3

"Hey Mr. Ellington : what are you doing to us ??
Did no one ever tell you that a diminished chord is supposed to be a passing chord ??
To sustain a single chord for 12 continuous bars is rare enough in the Jazz repertoire, but a diminished chord at that ! Really, are you having us on??"

Of course not.
The Duke probably knew more about harmony and diminished chords than all of us put together.
So what is the secret of this Go7 chord, which, the longer you look at it, takes on the shape of a fully covered and veiled mysterious passenger in this Caravan.
Who is this exotic passenger with her beautiful voice and her haunting eyes shown through the narrow opening just above her veil?

Before reading on see if you can find any clues as to her true nature.

Down - Up - Top - Jazclass Links)

CA 1.3 - The Mystery Passenger unveiled

The Duke is a discreet, but also very generous man.
He not just lifts the lady's veil, but shows her fully disrobed in her magnificent glory.
But only to those who care to look for her!

Here she is, in the very first four bars of the melody :

Audio 4

Once you realise that the Go7 chord in this song really functions as a dominant C7 chord (with a b9 thrown in for extra colour and the root missing to provide a bit of mystery) the whole A section harmony suddenly starts to make sense.
For look here :

Audio 5

The C7 chord (with or without the b9) is the V7 scale-tone chord of the F harmonic minor scale. It naturally leads to F minor.
The A section of Caravan is therefore a simple V7 - Im progression in disguise. The F minor target chord is in this case Fm7 which does not fit into the F harmonic minor scale, but the minor mood prevails.

Below the typical II-V-I chord progression for the harmonic minor. In Jazz the F minor triad is usually replaced by a full blooded Fm7 chord (which shifts the progression into the F Dorian mode).
Keyboard and guitar players often voice the V7 chord as a IIo7 chord, which fits smoothly into the progression as shown on the right below.

Audio 6

Any one of the four diminished chords can be used as a substitute for the dominant 7th chord.
Select the diminished chord that starts :

  • a semitone above the dominant chord's root

  • or on the 3rd, 5th or 7th chord tone of the dominant chord.

Audio 7

Down - Up - Top - Jazclass Links)

CA 1.4 - Improvisation

The most commonly selected scale for improvisation over a diminished 7th chord is the 8-note diminished scale.
This is a symmetric scale with the notes spaced at tone - semitone - tone - semitone - intervals, starting with a tone.

Audio 8

From the revelations above it is clear that, in order to reflect the true nature of the exotic passenger in the Caravan, the use of the (II-mode of) F harmonic minor scale is a much more appropriate choice for improvisation.
Use this scale for the first 12 bars over the Go7 chord, then switch to the F Dorian mode for the next 4 bars over Fm7. This is a good combination and nicely reflects the minor nature of the Caravan's A section.

Audio 9

If you improvise for a second chorus, make it interesting with some variety by using as an alternative the G 8-note Diminished scale.
Note that this scale contains the same notes as the C 8-note Dominant scale.


Down - Up - Top - Jazclass Links)

CA 1.5 - Modes of the 8-note Symmetric scale

The 8-note symmetric scale consists of alternating tones and semitones. It has 2 distinct modes, one starting with a semitone the other starting with a wholetone interval.

  • 8-note Dominant scale = semitone - tone - semitone - tone -

  • 8-note Diminished scale = tone - semitone - tone - semitone -

The 8-note Dominant scale contains all chord tones of the dominant 7th chord (1, 3, 5 and b7), as well as the b9 (Db above), #9 (D# above) and #11 (F# above). Use this scale therefore for dominant 7th chords, especially when they contain added altered notes.

The 8-note Diminished scale contains all chord tones of the diminished 7th chord (1, b3, b5 and 6).
It does not contain all the notes of the dominant, minor, half diminished and major 7th chords. It is therefore a unique scale for improvisation over diminished triads and diminished 7th chords.

Make sure to use these two distinct names for these two distinct modes. (Unfortunately this is not done by several prominent Jazz educators.)

These two scales are members of the 6 modes system the contemporary-classical French composer Olivier Messian used for many of his compositions. The wholetone scale is a third member of his system.

Down - Up - Top - Jazclass Links)

CA 1.6 - Caravan : Bridge

After the minor A section the Bridge in Caravan has a distinctly happier mood.
The chord progressions moves through a series of dominant chords in Circle of Fifths order until it arrives at Abmaj7, which is the major key ('related major') with the same signature as F minor. Then it returns to C7 in preparation of the final A section.
Here is a simplified version of the progression.

Audio 10
| F7 | | | |
| Bb7 | | | |
| Eb7 | | | |
| Abmaj7 | | C7 | ||

Use Mixolydian modes over all dominant chords, and the Ab major scale over Abmaj7 for improvisation.


One final observation about the story this song (I believe) perhaps has to tell.

  1. In the first two A sections (in minor mood) the Caravan is doggedly plodding along through the desert.
    It is very hot and dry and the sand is soft, making progress difficult and slow.

  2. Then, in the Bridge, could it be true ? The palm trees of a wonderful oasis appear at the horizon.
    The Caravan's mood suddenly becomes happy and its pace quickens. (I have reflected this by going into swing style on the Play-a-Long)

  3. But alas, the final A section (back in minor mood) suggests it was not an oasis after all, but just one of those illusionary fata morganas.

Down - Up - Top - Jazclass Links)

CA 1.7 - Downloading Bay

Lead sheets : Melody (Bb - Eb) Improvisation
Midi files : Melody Play-along

( Up - Top - Jazclass Links)

Copyright © 2002 - 2006 Michael Furstner. All rights reserved.