At the end of the previous article in the series, we saw how the C Major key can be built by applying a series of intervals on the root note, and then we went on to work out how to extrapolate that series of intervals onto the note of G in order to obtain the key of G Major.
We can produce all the rest of the major keys in a quick and ordered manner by selecting the whole scale and transpose all of its notes a fifth up. The resulting series of scales is what is called the circle of fifths, which is a system to navigate across all the keys within the chromatic scale, as well as through all the chords within a given key.
When we do this, we start to notice that a new pattern emerges: every time we move to a new key, we get a new alteration; in G Major, the F becomes F#, in D, the C becomes C#, in A, the G becomes G#, in E, the D becomes D#, and in B, the A becomes A#.
These alterations keep piling one by one with each shift, giving each key their own set of altered notes. This makes it possible to identify keys by looking at the alterations that are present in the notes. Based on this, if there are no altered notes, we know we are in the key of C, if there’s an F#, we’re in G, if there’s an F# and a C#, we’re in the key of D, and so on.
Another important discovery to be made with this technique is that when we try to transpose the note of B a fifth up, we don’t move to F but to F#. That’s because in the major scale all the fifths are perfect, except for the one that exists between B and F, which is diminished.
The first four Major keys in the circle of fifths
In the first part of this series, I mentioned how any musical scale can be obtained from the major scale. We can of course, as an alternative, commit to memory every single intervallic pattern of every scale instead, but the advantage of learning new scales as variations of the major scale is that we only have to learn the differences between the new scale and the major scale.
For example, in order to get the natural minor scale, which is the basis for working on minor keys, we simply have to lower the third, the sixth and the seventh notes of the major scale a semitone down. This is what is called the parallel key of a major key, which is a minor key built on the same root as its major counterpart. This not only changes the intervals of the scale, but also the resulting notes.
The key of C Minor
An even easier way to arrive at the natural minor scale is to shift the root of the major scale a third down without making any changes in the notes. This is what is called the relative key of a major key, which is constructed with the same notes but from a different root.
Relative keys change the intervals of the scale they’re derived from, but not the resulting notes.
The key of A Minor
Diatonic chords are the chords that we can obtain by stacking several notes of a particular key.
The most basic and important diatonic chords are called triads, which are three notes chords built on each of the notes of a given key.
To create a triad, we start with any note of the chosen key and add a third to it, and then another third to the previous note, which is also a fifth from the root note.
Triad of C Major
Since we are in a diatonic scale, that is, a subset of the chromatic scale, we don’t have to worry about whether the thirds are major or minor, we simply have to make sure we stick to the seven notes of the scale we’re in. One way to do this in Ableton Live is to create a stack of the seven notes of the major scale and place them outside of the midi clip’s loop and then activate the Fold switch. This way we leave out of the midi editor the notes that don’t belong to the key. Also, when working with chords, it’s necessary to duplicate the stack of notes at least an octave up or down in order to have sufficient notes to build all the chords we want.
Fold switch on with stack of C Major notes
Nonetheless, it’s important to know that the intervallic pattern of a perfect triad is formed by two consecutive thirds, one of them major and the other one minor.
If the first third is major and the second one minor, we talk about a major chord, and if the first third is minor and the second one is major, we’re talking about a minor chord.
Major scales contain three major triads built on the first, fourth and fifth notes of the scale, three minor triads built on the second, third and sixth notes of the scale, and a diminished triad built on the seventh note of the scale.
The seven triads of the C Major key
And that’s all for this second part of our series on music theory fundamentals in which we’ve delved deeper into keys and diatonic chords, two major topics of harmony theory.
In the next part of the series we’ll expand on functional harmony and modes in order to gain further knowledge about the relationships between keys and chords and how to apply that knowledge to write chord progressions and melodies.