Wherefore Art Thou, Progression Variation?
Updated: Apr 12
To progress from something nice to play, there needs to be something else nice to play. This "something else" needs to have relevance or contrast, and if contrast, then a logical contrast is preferable.
The first idea could be something like this, in the key of A Phrygian ...
| A min7 | D min7 | A min7 | Bb Maj7 :||
Here, the tonic chord of A min7 is quite obviously the anchoring factor in a harmonic sense.
So, that firstly is an example of playing a chord and then figuring out some other chord or two to play. And that becomes a four-bar progression, playable many times, with a sense of harmonic movement around the tonic chord.
Where to go from there? An option is to play another "pedal around the tonic" style of progression, and maintain the same modal key signature (in this case, A Phrygian).
Something like ...
| A min7 | F Maj7 | A min7 | E min7b5 :||
This "something else" has a relevance due to maintaining the same modal key signature.
The tonic chord does maintain a sense of dominance and focus. Is this musically recommendable? Depends on what the feeling of the songwriting requires.
Another option is to maintain the "modal key signature" of A Phrygian, although give a sense that a different chord is now the tonic chord. So this means, the seven enharmonic chords of the A Phrygian mode's "harmonic boundaries" are maintained. It's just that a different emphasis is given to a chord other than A min7.
Such as ...
| F Maj7 | E min7b5 | F Maj7 | G min7 :||
The idea of changing to a different modal key signature altogether is a potentially cool idea, although does require some kind of harmonic management, so to speak. In traditional harmony, there are traditional ways and means to accomplish this in a musically logical fashion.
These key change techniques are relevant and useful for modal composition, although sometimes their usefulness is more of a comparative template, to learn from and then spend some time in reflection, thinking about how the harmonic logic would then most suitably apply to a particular mode.
And so really this is surely a subject for another journal article. Essentially, the idea is, a key change is possible when writing a modal chord progression, whereby a chord or series of chords are played, that are not from the harmonic boundaries of the starting modal key signature.