A lot of guitarists are self-taught and have limited knowledge of music theory. They may have heard of scales – particularly the pentatonic scale in relation to guitar-playing – but they might not understand what scales are composed of, and how they relate to what you play on the guitar. In this article, I will try to explain the basics of the different types of scales in Western music (since some other cultures use different scales, but that’s a topic for another article).
Firstly, what is a scale? A scale (from scala, Latin for ‘ladder’) is simply a sequence of notes that sound pleasing to our ears in relation to one another. There are fixed mathematical relations between the notes, but that’s a topic for another article (here). There are several main types of scales, consisting (mostly) of different numbers of notes. I will start with the scale that contains all of the notes.
In all of these examples, I use the scale of C as the basic major scale. This is a common convention from keyboard instruments (pianos etc.) where the white keys are the notes of the scale of C Major. All of the different scales exist in all of the keys, though, i.e. starting from any of the notes on the chromatic scale – you just shift everything along the requisite number of semitones.
There are 12 different notes in an octave, with the octave note (e.g. the top C if you start from a lower C) being the 13th. Each of these notes is a semitone apart (semitone = 1 fret). So the full chromatic scale, starting from C, contains all of the notes like this:
C – C# – D – D# – E – F – F# – G – G# – A – A# – B – C
I used only sharp signs to avoid getting into the subject of sharps and flats. You don’t normally see some of these, particularly A# for example which is usually written as Bb, but they are the same note.
Next after the chromatic scale, we have the major scale which contains a subset of these notes, seven of them (eight with the top C again, whence comes the term ‘octave’), which make a more pleasing set. These are: C – D – E – F – G – A – B – C
To make this scale, we have dropped all of the sharp notes, which are the black notes on a piano.
The minor scale is similar to the major scale, in that it contains seven different notes. Actually, there are several variants of the minor scale, but the standard one changes three of the notes by dropping them down by a semitone (denoted by the flat sign, ‘b’). The C Minor scale therefore contains the notes C – D – Eb – F – G – Ab – Bb – C.
[Note: we use the flat sign here rather than the sharp sign (‘#’) so that each note has a different letter; using sharp signs, the scale would be C – D – D# – F – G – G# – A# – C, which is confusing.]
That minor scale actually consists of the same notes as a different major scale – Eb Major (Eb – F – G – Ab – Bb – C – D – Eb); the scale just starts on a different note. We will return to that idea in another article. These are called the relative minor or the relative major, and they are three semitones apart.
The difference between the major and minor scales is one of mood rather than anything else. Generally, the major scale is rather happy and upbeat, whereas the minor scale is sad and downbeat. Military marches are usually in major keys, and death metal is usually in minor keys!
Next we have a scale that is more familiar for guitarists, the pentatonic scale. Pentatonic means “five tones”, and a pentatonic scale contains five notes out of the twelve (plus the octave). The most commonly used pentatonic scale on the guitar is a minor scale, not a major one, and this is the minor pentatonic scale in C: C – Eb – F – G – Bb – C
The relative major pentatonic, similarly to the relative major and relative minor above, consists of the same five notes, starting on the Eb instead of the C.
A triad is another scale with only three notes. The basic major triad is as follows: C – E – G – C
If you play the notes of a triad in sequence (C, then E, then G etc.), that makes an arpeggio. If you play them together, they make a chord. On a guitar, chords often include one or more duplicate notes. The standard C chord (X-3-2-0-1-0), for example, contains the notes C – E – G – C – E, with the C and E notes repeated an octave apart.
Generally, the lowest pitched note in a chord should be the root note (i.e. the first note in the scale) – that’s why we don’t play the bottom E string in a C chord, even though E is one of the notes in the triad. A triad with a different bottom note from the root is called an inversion.
That’s enough about scales for now. I recommend sitting with your guitar or – even better – at a piano and playing through all of the different types of scales in order to understand them. Happy harmonising!