Basic Jazz Harmony

When putting chords together there are two aspects you should be aware of:

This is determined by the intervals between chord notes. To analyze the chord structure you have to break it into pieces:

1-The Root & The Fifth

The root is the reference from which all other intervals are measured (either aurally or theoretically) & the fifth doesn't play an effective harmonic role, it just makes consonance with the root, but this is not the case if the fifth is diminished (flattened) or augmented (raised) as this alteration has an important harmonic effect & totally changes the taste of the chord.  

2-The Third & The Seventh

The most important notes for defining the color of a chord; The third is the note which decides weather the chord is major or minor. If omitted you'll never be able to recognize the quality of the chord. The seventh interacts with the third according to the interval between them to give the chord its distinctive sound.

C E G B       Cmaj7         (major third & major seventh)

C Eb G Bb     Cm7          (minor third & minor seventh)

C E G Bb        C7            (major third & minor seventh)

C Eb G B   Cm-maj7       (minor third & major seventh)

3- Higher Extensions

These are the 9th, 11th & 13th with all the possibilities of alteration. Alteration is simply to lower or raise the note by a semitone. For example, instead of playing a G9 (G B D F A) you may play a G7b9 (G B D F Ab). Alteration is mostly used in dominant chords (discussed in details in the dominant chords section)

Now … Here are three examples on the analysis of major, minor & dominant chords in order to put things together.

The notes of a C major seventh chord are C E G B. Firstly, Look for the root & the fifth, here they are: C & G, the interval between them is a perfect fifth, a very stable & pleasant interval for our ears. Then look for the third & the seventh: E & B the same interval applies here, so this chord is considered harmonically stable.

For a C minor seventh chord (C Eb G Bb) the intervals between the root & fifth and the third & seventh are also perfect fifths so it is also a stable chord.

This means how chords resolve from one to another.

1- Circle Of Fifth

A good way to organize chords movement is to let the bass proceeds through a circle of fifth putting into consideration the key signature of your song, here is an example in the key of Eb major:

Cm7 Fm7 Bb7 Ebmaj7

The bass has moved through circle of fifth & all chord notes are derived from an Eb major scale.

You may add interest by introducing new notes outside the Eb major scale:

Cm7 F7 Bb7 Ebmaj7

The chord F7 (F A C Eb) introduced the note "A" outlining an Eb Lydian mode.

2- Two Five One

This chord pattern is probably found in most Jazz standards & used extensively as turn-arounds.

It is noticed that the 2-5-1 Progression is a subset of circle of fifth; that is the 5 is the fifth of 1 & the 2 is the fifth of the 5.

- Major Two Five One 

The Two chord is always a minor seventh, the Five is a dominant seventh & the One is a major seventh chord.

Dm7 G7 Cmaj7

These chords could be altered according to your taste..

Dm9 G7b9 Cmaj6

You may wonder what scales choice should fit this progression. On the Dm7 you may play a D dorian (second mode of C major), G mixolydian on G7 (fifth mode of C major). And of course, on Cmaj7 you may play a C major scale.

So a good choice to start improvising on a Two Five One in C major is the C major scale as one mode of it fits the Dm7 & other mode fits the G7 chord.

- Minor Two Five One

In this case the Two chord is a minor seventh flat five (m7b5), sometimes called a half diminished chord. The Five chord is a dominant seventh. If you derive the Five chord from a minor scale, you will get a minor seventh chord. But this chord doesn't effectively resolve to the "key chord" as the dominant seventh does.

The dominant seventh chord introduces a new note to the minor scale; a perfect seventh instead of flat seventh. This would be B instead of Bb in the key of C. This note adds a sweet chromatic effect to the two five one.

Dm7b5 G7 Cm7

You may add some variations to the standard form..

Dm7 G7#5b9 Cm9

Your first choice on the Dm7b5 is to play a D Locrian, this is a diatonic scale in the key of C minor as both C minor & D Locrian are mode derived from Eb major scale. 

When it comes for the G7 (altered) you have several choices. You may play a G altered scale for great tension, play a G Mixolydian which is related to the C major scale to add harmonic richness to your playing by getting out of the C minor & switching to a mode of the C major, or you may play a C harmonic minor to fit the note introduced by the G7 (B), or may be you don't change your scale at all & play a C minor scale over a G7; in this case when you play the Bb note you are actually playing the sharp ninth interval referred to the G enriching the harmonic content of your improvisation.

And simply you can play a C Dorian or a C minor on a Cm7 chord. There are infinite possibilities you may explore for using new scales & chords.

Thinking Modal

Some Jazz songs contain just few chords where two chords or two keys with few variations are used; one is the transpose of the other, usually a semitone above. A typical modal song follows the form AABA, where the first key lasts for 16 measures. The most popular examples for modal Jazz are the songs "So What" by Miles Davis & "Impressions" by John Coltrane.

Flat Third Transpose

(This name is not anyway a familiar one)

One of the most exciting things you can think of when it calls for a transpose in a minor key.

This transpose is done by shifting the song key by an interval of three semitones. This key change can be heard in the standard "Nostalgia At Times Square". 

1- Key Resolution 

The C minor is the sixth mode of Eb major scale. So when you switch from C minor to Eb minor, you are actually moving from a mode of the Eb major scale to Eb minor generating an exciting sound related to switching from a major to minor key.

2- Bass Resolution

The flat third is the most important note in a minor key & you can NEVER call any scale a minor if it doesn't contain this note. While improvising using a minor scale try to end your statement on the flat third, you'll find it a very pleasant choice & you'll confirm that you are in a minor key. Therefore our ears appreciate the bass resolution from C to Eb.  

3- Chord Notes Resolution

The Cm7 chord notes are C Eb G Bb, the Eb chord notes are Eb Gb Bb Db, you'll notice that the 3rd & 7th of the Cm7 are kept the same Eb & Bb in the Ebm7 although they are now considered the root & fifth in the new key, while the root & fifth of the Cm7 C & G are flattened to Db & Gb (the seventh & third of Ebm7 respectively.

This resolution generates great tension by keeping two notes unchanged & flatting the two other notes.

Lastly, the same melody could be harmonized in several ways & you should select carefully the chords according to the mood you want to establish. As this point is sometimes ignored & chord choice is based only on how far they fit the melody..

So before choosing your chords think of the alternatives to accurately establish your mood.