I did a post recently dealing with categorizing chords to make them easier to use. We know that in any key, the I, IV and V-chords comprise what we call primary chords, and they are the most common ones you’ll find in most pop songs.
Beyond those three, the ii, iii, vi and vii-chords are categorized as secondary chords, with that vii-chord itself probably being the least-used of the seven naturally-occurring chords in any major key.
You can write a lot of wonderful music using just those chords. But sometimes you want to branch out and throw in something that might surprise your listeners: chords that don’t naturally exist in a key.
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The problem with using chords that are foreign to a key is that if they’re just thrown in for interest’s sake, they can sound a bit confusing and can negatively impact a listener’s experience.
Here’s a short list of chords that don’t normally exist within a song’s key, but are commonly used, and can make a powerful impact on the sound of your progressions:
A flat-VII chord is a major chord built on the flattened 7th note of a key. If your song is in C major, a flat-VII will be a major chord built on Bb, giving you these notes: Bb-D-F.
It’s a great chord to use either as a replacement for a V-chord:
C F Am Bb C
…or it is a good way to get from a I-chord to a IV-chord:
C Bb F G C
In the key of C major, a flat-III is an Eb chord, using the notes Eb-G-Bb. It moves nicely up from a I-chord, and connects easily to the IV-chord:
C Eb F G C
It also works well in combination with the flat-VII chord:
C Eb F Bb C
A secondary dominant chord requires a lengthy description, but here’s a shorthand way to describe one possible type: if, in your progression, you use a ii-chord (Dm) which is followed by a V-chord (G), that Dm chord can be changed from minor to major, becoming a secondary dominant chord in the process:
C Am D G C
You can change any minor chord that is followed by a major or minor chord 4 notes higher, and you’ll get different forms of secondary dominants. Here are a few progressions that use secondary dominant chords (shown in italics):
C Am Dm E Am
C F A D G C
C Eb D7 G C
C B7 E7 A7 D7 G C
Augmented Sixth Chord
Here’s the quick way to form an augmented sixth chord: Let’s say you’re in the key of C major. Find the 6th note (A), lower it by a semitone (Ab), build a major triad on that note (Ab-C-Eb), and then add a minor 7th at the top (Ab-C-Eb-Gb), giving you Ab7. An augmented sixth chord usually resolves by moving to a major chord whose root is a semitone lower. So Ab7 will resolve to G.
The augmented sixth is used in the bridge of Lennon & McCartney’s “Oh! Darling“, and also uses a secondary dominant:
Bridge of “Oh! Darling”: D F7 A B7 E7 F7 E7. The B7 is the secondary dominant, and the F7 is the augmented sixth.
Some other progressions in C major that use the augmented sixth:
C Am Ab7 G C
C F E7 Am Ab7 G C
Dm Em Am Ab7 C/G G C
Advice on Chord Choice
I’ve always felt that songwriters spend a lot of time worrying about a chord progression that sounds “boring”, when in fact the main worry is a chord progression that simply doesn’t work.
Having said that, however, it can add a shot of creativity to music if you add in chords that don’t normally belong to a key. But those chords need to be used sensibly, not simply tossed in without thought. Curry can make chicken taste great, but you wouldn’t likely add it to coconut cream pie!
Written by Gary Ewer. Follow Gary on Twitter.
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