Non-Diatonic Chords

Strict diatonic note and chord selection provides a gigantic amount of possibility for song-writing and solo'ing; however, it still places us inside a box that we occasionally want to escape. The simplest way to do this is to borrow chords or notes from other scales/keys.

PreReqs

• Music Theory Basics
• Music Theory - Diatonic Chord Progressions
• Music Theory - Minor Keys
• Harmonic Minor and Augmented Chords
• Circle of Fifths
• 7th Chords

Secondary Dominant

also called borrowed dominant

The most common borrowed chord is the V (or V7) of V chord, commonly notated as V/V or V7/V.

Notation

The "/" indicates that the chord is borrowed. The bottom or right side of the slash is the key that is being borrowed from. The left or top side of the slash indicates which chord from that scale is being used. V/V means the fifth diatonic major chord of the major key whose root is the fifth diatonic note of the current key.

Function

It is essentially a dominant function chord whose function is to resolve to the dominant chord of the current key. That chord then resolves to the I or i chord. V/V - V - I.

Example

In C Major, the progression would be D - G - C. D is borrowed, as Dm is the diatonic chord. The raised F# that makes it a major chord also gives it the dominant function to resolve a half step to G, as part of the G chord.

If the D Major chord did not resolve to G Major, demonstrating its dominant functionality, we might alternatively analyze this as a II or borrowed major from some other key.

In the key of G Major, V/V would be an A Major chord. Let's look at both keys:

	V/V	V	I
C Major	D	G	C
G Major	A	D	G

Notice that both progressions feature D - G. In G Major, it's V - I. In C Major, it's V/V - V. G Major is built on the fifth note of C Major; it is the V key. In both progressions they contain the same basic dominant-resolution feel, yet by occurring at different parts of the V/V - V - I progression, they serve somewhat different functions.

Parallel Major/Minor

Chords can also be borrowed from the parallel major/minor of the current key.

Borrowing from Minor

When using a major key, chords can be borrowed from either the parallel natural or harmonic minor keys:

	iio	bIII	iv	bVI	bVII	viio7
C Major	D dim	Eb	Fm	Ab	Bb	Bo7
G Major	A dim	Bb	Dm	Eb	Fb	Fo7
Borrowed From	Nat/ Hrm	Nat	Nat/ Hrm	Nat/ Hrm	Nat	Hrm