Sub-Dominant Chords

Sub-Dominant Chords

Sub-Dominant Chords are chords of movement.
In contemporary harmony, sub-dominant is one of three functional harmony categories.

Functional Harmony
Tonic chords of rest or resolution	Sub-Dominant	Dominant chords of tension moving to tonic

Sub-Dominant chords use the fourth scale-degree (fa) in their construction. Sub-Dominant chords also usually contain or support the tonic note (do). Scale-degree seven (ti), the leading-tone, cannot be a chord-tone if the tonic note (do) is not present as a chord-tone. This will change the function of the chord to dominant.

Diatonic Sub-Dominant Chords
Primary		Relative
IV F		IIm Dm
Modal Interchange Sub-Dominant Chords must support any existing melody
Major Seventh	Minor Seventh	Seventh	Minor Seventh Flat-Five
bVII^maj7 bII^maj7 Bb^maj7 Db^maj7 ------------ bV^maj7 Gb^maj7	Vm⁷ IVm⁷ Gm⁷ Fm⁷ ------------ bVIIm⁷ Bbm⁷	IV⁷ bVII⁷ F⁷ Bb⁷	IIm7^b5 Vm7^b5 Dm7^b5 Gm7^b5