Chords from Other Keys
If you want to spice up some of your own songs, sometimes taking a chord from outside the key can give you the flavor you’re looking for. Or maybe you want to jam over a progression and there’s just one chord that messes you up. In many cases, its probably a chord taken from somewhere else. Let’s look at a couple of methods often employed by music creators.
The first “trick” is using borrowed chords. This is sometimes referred to as modal interchange. It’s a very simple concept; replace a chord in your key with one from a parallel key. A great example of this is Santo and Johnny’s Sleepwalk, used to great affect in the movie La Bamba. The progression (in C major) is as follows:
You’re probably already familiar with this sound. It’s the standard “50’s progression” known as a I – vi – IV – V. The catch this time is the IV chord. It has been replaced by a minor iv chord from the parallel key of C minor. Normally the IV chord would be an F major, but these guys decided to do otherwise. A simple way to figure it out is to write out the chords from two keys and place them side by side.
|C major||C natural minor|
|I – C major||i – C minor|
|ii – D minor||ii° – D diminished|
|iii – E minor||♭III – E♭ major|
|IV – F major||iv – F minor|
|V – G major||v – G minor|
|vi – A minor||♭VI – A♭ minor|
|vii° – B diminished||♭VII – Bb major|
So as you can see, the F major and the F minor chords are easily interchangeable. They both occur on scale degree 4 and they’re both some kind of F chord. What’s more, both chords function as pre-dominant in their respective keys. But let’s not stop there. We’ve got a vi chord in this progression. What if we swap it out for the ♭VI chord in C minor?
So as you can see, the F major and the F minor chords are easily interchangeable. They both occur on
scale degree 4 and they’re both some kind of F chord. What’s more, both chords function as predominant in their respective keys. But let’s not stop there. We’ve got a vi chord in this progression.
What if we swap it out for the ♭VI chord in C minor?
Another tested and true method is the use of secondary dominants. The essential idea is that we can
get from one chord to another by using a borrowed dominant chord. Let’s take the first few chords of
the classic tune Crazy, by Willie Nelson.
|I||V of ii||ii|
We’re very firmly in the key of B♭ major by the time the intro plays through (on the Patsy Cline version anyways). So what gives with the G7? It’s not part of the key. That chord is a secondary dominant that tonicizes the C minor chord; essentially a borrowed dominant. If we were in the key of C minor, we could raise scale degree 7 by a half step to create harmonic minor. G7 then, would be our dominant seventh chord built off of scale degrees 5 –7 – 2 – 4. So in effect, Mr. Nelson borrowed this dominant chord to move very convincingly from the B♭ major chord (I) to the C minor chord (ii). That chord is technically the V of C minor, so we analyze it as V of ii.
Because dominant – tonic movement is such a strong sound, borrowing a dominant chord is a great way to add momentum to a chord progression without having to stick to the chords in one key. It’s also a great way to change keys altogether; using a secondary dominant to establish a new chord as your tonal center. If Willie hadn’t wanted to stick to B♭ major in his song, he could’ve easily just continued in C minor.
These types of chords also trip up beginning improvisers. You may be playing over a track labeled G major, but one chord happens to be either modally exchanged or some kind of secondary dominant. All of a sudden that one scale you were using sounds like garbage. In these instances, it’s much safer to improvise chord to chord; that is playing notes that work over each individual chord rather than the progression on the whole.