Scale Theory
What is a scale and why should guitarists care about scale theory?
A scale is an orderly series of notes. The series can ascend in pitch or descend in pitch. The difference in pitch, from one note to the next, is defined by the scale type. There are a number of types, but this article will introduce the chromatic scale and discuss the building block of major and minor scales, the tetrachord.
| SIDEBAR: This lesson covers what scales are... not how to play guitar scales. First you need to understand what a scale is, then you can learn to play major, minor, or other scales. Also I cover only the scales used in music of the western world. You'll have to look elsewhere to learn about scale theory for other parts of the world. |
You should care about scale theory because the harmony, melody, and chords of nearly all music is composed of notes from the primary scale, or key, of the song. If you understand the scale, then you can make some assumptions about the chords you'll play, which notes are OK to play for a solo, and more.
If you understand the notes of each scale, how to construct them, and how scales relate to each other, you can learn, write and perform music more efficiently.
See the discussion of Chords, Scales & Key Relationships on the Basic Chord Theory page for additional basics of music theory and keys.
| SIDEBAR: Guitarists often refer to Chord Progressions of a song. What they are actually discussing are triads of the song's key that sound 'right' to the human ear when played in sequence. However, since guitarists play chords... we understand chords... so, we refer to Chord Progressions. |
Chromatic Scales
A one octave series of tones that includes every half-step note is called a chromatic scale.
That's quite a mouthful, I suppose, but it's really rather straight forward once you understand it.
On a guitar, the easiest way to play a chromatic scale is to pluck every fret position on a single string until you've played 13 ascending or descending notes. For example, below is the TAB for an E-chromatic scale.
Beginning with the open E string, play the open string up through the 12th fret. (The following diagram is guitar TAB, if you don't understand how to read it, take a look at my Guitar TAB page.)
------------------------------------------
------------------------------------------
------------------------------------------
------------------------------------------
------------------------------------------
0--1--2--3--4--5--6--7--8--9--10--11--12--
The notes of this E ascending chromatic scale are:
E-F-F#-G-G#-A-A#-B-C-C#-D-D#-E
When tones are ascending, any half-steps (sharps/flats) are identified as a 'sharp' note. When descending, they are identified as a 'flat' note.
So, if you play:
------------------------------------------
------------------------------------------
------------------------------------------
------------------------------------------
------------------------------------------
12--11--10--9--8--7--6--5--4--3--2--1--0--
The notes of this E descending chromatic scale are:
E-Eb-D-Db-C-B-Bb-A-Ab-G-Gb-F-E
You can play similar chromatic scales on any string, beginning at any fret, as long as you play a total of 13 consecutive notes.
Here's one way to play the same chromatic scale by moving across the fretboard:
------------------------------------------
------------------------------------------
------------------------------------------
0--1--2-----------------------------------
0--1--2--3--4-----------------------------
0--1--2--3--4-----------------------------
Tetrachords - Building Blocks For Scales
You may not find this topic on a lot of introductory pages about scale theory, but if understand tetrachords it will be much easier to understand major and minor scales.
Major and minor scales are built on combinations of tetrachords. If you understand tetrachords, you'll find it's easier learn how to construct major and minor scales.
A tetrachord is a series of four notes. Not any four notes, but four ascending notes with specific distances between them.
For major chords the distances are: whole-step, whole-step, half-step.
For minor chords the distances are: whole-step, half-step, whole-step
| SIDEBAR: "Wait a second, that's only three notes" some of you may be thinking. No, it's three steps. If you have three steps, you're using four notes. You have to count the starting point too. Read on for the conclusion of our introduction to scale theory... |
A 'step' is the distance from one distinct note to the next.
If you ever played the children's game "Mother May I?" think of half-steps as "baby steps." It's the smallest step you can take and still move forward. A whole-step is two half-steps.
On the guitar, it's easy to visualize this scale theory concept: A half-step is the same as moving from one fret to the next on the same string; A whole-step moves two frets on the same string. There are, of course, ways to move one half-step, or one whole-step across strings, but let's not worry about that now.
Let's take another look at the chromatic E scale to find some half-steps and some whole-steps:
E-F-F#-G-G#-A-A#-B-C-C#-D-D#-E
E to F is a half-step, because the very next note after E is F.
F to F# is also a half-step, as is F# to G.
F to G is a whole-step since you've moved two half-steps (F to F#, and F# to G).
G to A is also a whole-step, as is C to D.
Think you've got it?
Test yourself. See if you can answer this question: Is E to F# a half-step, a whole-step, or something else?
Answer: Since E to F is a half-step, and F to F# is a half-step, then E to F# must be a whole-step.
Great job... You're just about through with our lesson on introductory scale theory. Next, let's take work on building one major tetrachord from our E chromatic scale.
We know that a major tetrachord is four notes, built from: whole-step, whole-step, half-step. We also know what half-steps and whole-steps are. Let's build our first tetrachord from the beginning of this E chromatic scale:
E F# G# A
W W h
In the above example, W shows where the whole-step's are, and h identifies the half-step.
So, our first major tetrachord is: E-F#-G#-A
You've completed your introduction to basic scale theory, and you're ready to learn about Major Scales and Minor Scales.