We'll be working in the key of C, since it's the simplest key for me. And, since I love acoustic rock, the progressions in this lesson will have that acoustic rock feel.
To begin, I'll tell you what a relative minor key is:
A relative minor key of any major key is the minor key that has the same key signature as the major. For example, C Major's relative minor is A minor, since they both have no sharps or flats.
Luckily for us, we don't have to figure out key signatures, because:
The root of the relative minor key is the 6th scale degree of the major key. A is the 6th of C, A is the relative minor of C. E is the 6th of G, E is the relative minor of G.
As a point of notation, when I give a chord progression, say, I-IV-V, I mean that you should return to the I and just keep playing the same progression (or end on the I if you're done). Other people would call this a I-IV-V-I progression, but my progressions will just keep going around in circles anyway.
Using The Relative Minor Chord In A Chord Progression
Now that we know what it is, let's try to use it. If you've done any reading on chord progressions, you'll be familiar with the I-IV-V progression that is oh so familiar in music. For now, let's keep I-IV-V as our theme, and do some variations on that theme using the relative minor.
The first variation we're going to use is I-vi-IV-V. Here, we're using the relative minor as a quick interruption to the major progression. In the key of C, these chords are:
C -> Am -> F -> G
Notice how C and A sound like they mix when you're in this progression, and also notice how, once you're out of A and into the F chord, the progression sounds a bit different from the C -> F -> G. That little bit of minor takes the entire thing in a new direction. Musically speaking, this is because the iv scale degree is an embellishment to the progression and adds a bit of character, but doesn't fundamentally change anything. In other words, while we're still fundamentally working with the I-IV-V progression, we added a touch of embellishment, making it sound different but not changing the function of the important chords.
A second way to use the relative minor chord is to let the V chord play with it a bit. A simple progression that lets you do this is: I-IV-V-iv-V. Notice how, here, we had to go back to the V before we were done. This is because iv doesn't really lead into I as well as V does (musically, V creates tension, which is resolved by going back to I. iv does not). In this progression, the iv chord (remember, our relative minor chord) acts to make the progression last longer. In the key of C, the chords are:
C -> F -> G -> Am -> G
The last progression I'm going to show you will really make that resolution sing out.
It's almost the same as the one above, but now we're using an extra IV chord. This progression goes I-IV-V-iv-V-IV or, in the key of C:
C -> F -> G -> Am -> G -> F
Notice how going from G to Am doesn't do much for the tension we've built up to (it's still there, but Am doesn't increase or decrease it), and notice how it really sounds like this progression takes us home to C when we start it all over again. Contrast this to the simpler I-IV-V-IV progression and see the difference that the iv chord makes.
Just like before, it doesn't change the fundamental feeling of the progression, it just changes its character.
Making The Relative Minor Do Something More
Now, let's move away from just using the relative minor chord, and start using the relative minor *key*. We're going to move away from the I-IV-V progression for the next two things I'll show you.
First, we're going to explore the relative minor key to mix two chord progressions into one. Consider this: I-iv-ii-V or, in C major:
C -> Am -> Dm -> G
See how the Am seemed to lead into Dm which seemed to lead into G? How did that work? Well, considering only the two middle chords, Am->Dm, we see that this is actually a i-iv progression in the relative minor key, meaning that Am and Dm work together much in the same way that C and F do in C major. But that's not all. Am and Dm work together, but Dm leads into G. Musically, this is because the ii chord has much the same function as the IV chord. So, considering this progression, it has the same function as the very first progression I showed you, but uses the relative minor to entirely change the way it sounds.
Finally, we're going to embellish this a bit by working with the v chord in the relative minor to work with us in the major key. As a starting point, try this chord change:
C -> E
See how they seem to go into each other? This is I-iii, which works really well (and is also the beginning of David Bowie's "Major Tom", if you were wondering). Now, using C as an anchor, here is a really neat progression that brings together the major key and its relative minor:
C -> Am -> C -> Em -> C -> Am -> Dm -> G -> C
Do you see how heavily we were relying on C? This is because we are fundamentally in C major, not A minor. If we stray too far from C major by just going straight into an A minor chord progression, we'll get that lost feeling where our ear is trying to figure out which key we're in. Plus, the minor key doesn't really have a i-iv-v progression that does the same thing as the I-IV-V in the major progression (take a look at jslick07's excellent lessons on chord progressions to understand why). Try it! Do: C -> Am -> Dm -> Em Can you see how it doesn't *quite* work as well?
This was a basic introduction to playing around with the relative minor chord and the relative minor key. Your job now is to experiment with other chord combinations in this set and see what works and what doesn't.