When we face challenges involving any of the seemingly impassable faces of music, I personally always try to keep prudence as my chief counselor. Everything we'll discuss in this article consists of structures that have worked for me personally, so if they help anyone advance in understanding one small parcel of the many that make up music, we'll have achieved our main goal.
There are many other models for understanding how scales, tonal schemes and so on work. What I'll lay out from here on is simply a way that has worked for me, but there are many others; each person has to find the one that works for them.
Before we start talking about scales proper, I'd like to put them in context and so pin down their framework of study a bit more. In fact, there's always a lot of attention paid to the word "scale," but not so much to the setting in which it operates, which is why I'd like to begin by discussing the concept of "key." So, without further ado, let's get down to business.
Initial Concepts: Tonality
We can divide a piece of music according to many criteria: tempo, melody/harmony, style, and so on. If we look at harmony, we can make one big division: modal music and tonal music. We'll set the first aside for another occasion. Tonal music, we can say, is music governed by the conditions that tonality establishes. But the question that comes to mind is: what exactly is tonality? It is the set of notes and the intervallic relationships among them. And therefore the chords generated from them, as well as the relationships of attraction and separation among the components of the key themselves, known as degrees. Within this system, every note and/or chord has a given tonal function, which leads us to the conclusion that tonality doesn't consist only of the notes, and therefore the chords formed from them, but also of the laws of attraction and ordering that the elements of the key have among themselves. We'll call each of the chords the key generates by a canonical name: degree. But the next question we might ask is: how does a key begin? For that we must go to its essence, which is the major scale itself. Because of certain acoustic matters, and therefore of the way a note's wave travels, a note doesn't produce only itself: a variety of harmonics and resonance phenomena are also generated, and many other things happen that we don't hear. That gives rise to the major scale, where the intervallic relationship is: whole step, whole step, half step, whole step, whole step, whole step and half step. So, for example, if we start with C (DO) as degree I, or tonic, we get the following notes:
C – D – E – F – G – A – B
Forming the C major scale.
Another example, to clarify things a bit more, would be if we want to know the notes of G (SOL) major, that is:
G – A – B – C – D – E – F#
And of course each of the notes keeps the interval relationships we explained above. We should also note that the symbols # (sharp) and b (flat) appear, with which we can raise or lower by a half step the note they're applied to. If we add to this scheme, which is simply the major scale, the chords that can be formed, first at the triad level and later as seventh chords, we get the key proper. That is the minimal expression of a key, since from here on we'll keep fleshing it out. For example, using C major and considering the first degree, we have C E G (root, third and fifth), which yields the C major chord, and for D we have D F A, which yields the D minor chord. And so on, we generate Scheme 1.
On the other hand, if we consider the general case, represented by degrees, Scheme 2 would appear, which we can use in all cases.
We can consider this a tonal scheme, which in a large percentage of cases will serve to frame many songs or parts of them.
But I'd like to go further in and expand the concept of key, arriving at what I call "the grand key." In that case we can include, besides the key we've explained so far, a set of nearby keys that we can use easily. The first step to think about is what is closest to the major key; take C major as the example: its relative minor, that is A minor, simply a sixth above. In this case the chords of C major and A minor are the same, but as we know the tonal functions vary, so it is very common to move from C major to A minor and vice versa. At the same time, within C major we can consider two adjacent keys very close to it, namely G major and F major. The only difference between C major and G major is the F#. The same happens with F major, whose only difference from C major is the Bb. So, in the general case, we could say that we'll use any key that is only one accidental away from the original. That is, we can use any chord from G major and F major over C major without any problem. Put abstractly, we can use the two major keys generated from its IV degree and from its V. In addition, we must add to the scheme the relative parallel exchange, meaning that if we're in the key of C major, we can use the chords generated in the key of C minor, and so use any of its chords within the key of C major. For example, I recommend using chords like Ab, Bb, or G min within C major; they give a very particular color. We could start a debate here since, if we're strict, we can say we're modulating from C major to C minor or A min or G major, and so on, but as it can happen so frequently, I include all these keys within the "grand key" of C major.
At this point we can say that we have the key proper, of course its relative minor, and its two adjacent keys, plus its relative parallel exchange. But if we follow the thread that the minor key gives us, the one generated from its sixth degree, we can consider a scale that arises from it, which is very interesting: the harmonic minor scale. It is a scale of minor character, born from the fact that the natural minor scale has no leading tone, that is, the note a half step from the tonic. The harmonic minor, then, is characterized by being a minor scale like the natural minor but with a major seventh, so it sits close, a half step, to the tonic. As a result, the harmonic minor scale moves in and out of C major with relative ease, as do all the chords it generates, which are quite attractive, since in it we can find diminished and augmented chords, a dominant for the minor tonic, and so on.
Just as we've allowed the harmonic minor to enter the key, we should expect its traveling companion to appear too, namely the melodic minor. We can understand this scale as the need to reduce the interval of a whole step and a half that exists between the sixth and seventh degrees of the harmonic minor scale. For that reason the melodic minor consists of a minor scale with a major sixth and a major seventh. We have the scale, but also all the chords it generates, at our service if we want to use the major key. It's worth mentioning that the melodic minor scale gives us several very tasty chords, that is, chords that sound challenging in terms of timbre but are perfect once introduced in context.
In summary, we can say that within the development we've just laid out there are parts that may not be, as I like to say, "by the book." But personally, they've helped me build a model that gives us the tools to solve any circumstance that might come our way.
Scales
We could begin with a general overview of which scales exist, or what they sound like, or simply which scales we use and what for. But I find it more important to look at how scales are created and where they come from. If we know the origin, we can save ourselves a great deal of memorizing them all. We must start from two crucial subjects: the natural major scale and the natural minor scale. The major scale is the one we explained in the previous section, and it was the central axis of all our reasoning (Scheme 3).
With its intervallic distances: 1 whole step, 1 whole step, half step, 1 whole step, 1 whole step, 1 whole step and half step.
The other great scale is the minor scale, which is exactly the same as the major but starting from the sixth degree. It therefore looks as shown in Scheme 4.
From this point on we establish these two scales as the canonical forms. We can start removing, adding or moving any degree; that allows us to generate new scales, so to speak, since the vast majority of scales consist of what we've discussed above. So let's start altering the major. The first case to consider is removing some notes, but the question is: which ones? As you might guess, the notes that can give us a bit more trouble are those a half step from the next one, so the IV and VII degrees, which in C major are F and B, are the candidates to disappear and generate the new scale, which is none other than the C major pentatonic scale, which gets used in just about any style of music, although as we know the blues is its perfect home. As a side note, the scale is called pentatonic simply because it has only five notes, which in the key of C major would be C, D, E, G, A. That is, as we said before, we eliminate those intervals that can at some point be "complicated," since they sit a half step from the third and from the tonic.
Conclusion
In this installment we've focused mainly on establishing the foundations from which we can later build scales, arpeggios, and so on, and thus keep a solid, strong structure in the face of the doubts and questions that assail you with every song you transcribe or compose. We'll keep digging deeper into the subject.