Barrowing From Parallel Keys
Parallel keys are major and minor keys with the same tonic. Parallel keys are different from Relative keys and if there is any confusion between these, click
here for explanations on both of these.
This method of chord substitution allows you to at any time borrow a chord (or chords) from the parallel key. To do this you look at the
Roman Numeral chords and replace one number with the same number from the parallel key.... Let's see an example to illustrate.
If you are playing a I IV iii vi progression in the key of C major then you have the chords:
C F Em Am
To figure out what chords you could replace these with, look at these Roman Numeral chords in the parallel key of C minor. Then make the substitutions...
The chords for the key of C minor:
Cm Ddim Eb Fm Gm Ab Bb
i iio III iv v VI VII
i = Cm
iv = Fm
III = Eb
VI = Ab
Therefore you could replace the C with Cm, the F with Fm, the Em with Eb, or the Am with Ab. So now pick one of the chords from the parallel key to substitute into the original progression like the following examples.
The
Bolded chord indicates the chord that was substituted.
C F Eb Am
Cm F Em Am
C Fm Em Am
etc...
That is the basic idea. For simplicity, this lesson only replaced one of the chords to illustrate the idea, but you can replace more than one chord in the progression. You can even replace the entire thing.... In fact, if you replaced
all of the chords in the example above, the new progression would be i iv III VI (Cm Fm Eb Ab). This is the method used to change keys which is covered in the lesson on
Modulation.