Piano Improvisation with Rosa

Diatonic chords are derived from teh same pattern scale and funciton within the same key.

These chords are built on each note in the scale and are labeled with Roman numerals.

eg. C major key:

Start on C.

Dm7 starts on the ii chord.

G7 starts on the dominant 5th chord. V7 chord.

In functional harmony, the ii chord typically progresses up a perfect 4th or down a perfect 5th to the V chord. (which in turn progress up a perfect 4th or down a perfect 5th) to the I chord.  Technically this is called ii7 – V7 — IM7 progression.

or ii V I

I vi ii V I

Another common variant of this progression adds the minor chord built on the 6th degree of the scale. Usually this progression occurs in the sequence:  I vi ii V I

CM7  Am7 Dm7 G7 CM7

• sometimes the vi and ii chords are changed to dominant 7th chords and are referred to as secondary dominants.
• The dominant chord on the 6th degree has a V-I relationship to the ii chord, sometimes called V/ii (pronounced as V of ii)
• and the dominant chord built on the 2nd degree has a V-I relationship to the V chord, so they are called V/V  r

I  —  V/ii  —  V/V —   V —   I

The vi chord

vi chord can be replaced with a half diminished chord built on a chromatically raised first scale degree and the V chord replaced by a fully diminished chord built on the chromatically raised 2nd scale degree.

In functioning harmony, diminished chords are typically built on the 7th note (or leading tone) of the scale.  Because these two chords form vii dim – i relationships to the ii and iii chords, they are called secondary leading tone chords and labelled vii dim7/ii  and vii half dim7/iii respectively.

CM7 —  C#dim7 —  Dm7  —  D#half-dim7 —  Em7

I  — vii dim7/ii  —  ii  —   vii half-dim7 — iii

iii chord subbing I

Frequently, a minor chord built on the 3 rd degree of the scale is sbustituted for the I chord, creating:

iii  —  vi  —  ii  —  V  –  I

or

iii  V/ii  –  ii —  V  –   I

When one of these progressions occurs at the end of a tune, it is referred to as ‘turnaround’.

Em7 A7  Dm7 G7 Cm7

Tritone

It is common to replace the V chord with the dominant 7th chod on augmented 4th away creating a tritone substitution built on the flattd 2nd degree.

Dm7   Db7  Cmaj7

ii trone sub  V-I progression in C major

On rare occasions, the bVII7 chord substitutes for the V7 chord. It is approached from either the ii chord or the iv chord borrowed from the parallel minor key.

Dm7   Bb7  Cmaj7

ii –  bVII  –  I in C major

Fm7   Bb7  C major

iv —  bVII –  I

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The 2 5 1 progression is the most common chord progression in jazz

Being able to recognize the progression greatly simplifies the process of improvising on chord changes.

C major — ii chord would be colored by a D dorian scale

V chord — by a G mixolydian scale

I chord — by a  C major scale.

These 3 scales all contain the same notes, therefore you can remain in one key when improvising over all 3 chords in the progression.