In all likelihood, you can play. You may even be able to play some seriously technical stuff. But, here’s the nagging problem: You don’t fully grasp or understand the concepts behind the notes and patterns you routinely use. The scales you play are still a bit of a mystery. If you’re like me, there’s something in you that knows it would be easier if you understood guitar scale theory.
And it’s not that you want to know all music theory. But, just enough to help give meaning to fretboard movement. The right kind of music theory gives us a better understanding of the scales we play and why we play them.
In my attempt to explain guitar scale theory, I’ll use enough theory to thoroughly discuss the concept while avoiding information that doesn’t benefit you directly in your understanding of the fretboard.
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Knowing a Little Theory
For a long time, I didn’t know any theory.
I’ve always had a good ear but, didn’t really delve into theory until I started to realize that I was simply memorizing patterns without really knowing how or why they worked.
We’re doing ourselves a disservice if we don’t understand the basic theoretical concepts behind guitar scales.
In this post, I’ll show you how to understand guitar scale theory in short paragraphs and plenty of pictures.
We’ll only cover what you need to know for guitar scales to make fretboard sense.
Let’s jump in.
Read more: Guitar Lessons 101
Guitar Scales Theory Explained
The most basic explanation of a guitar scale would be the following:
It’s less scary once you realize that in its most basic form a scale is little more than an ascending or descending sequence of notes.
Further, these scales are ordered by pitch.
Anssi Klapuri, in Signal Processing Methods for Music Transcription, defines pitch as the following:
Pitch is a perceptual attribute which allows the ordering of sounds on a frequency-related scale extending from low to high.
In other words, a scale is an ordered series of notes based on frequency.
How to we break this down on the fretboard?
We start with basic intervals, whole and half steps.
Whole and Half Steps
We’ve already established that scales are a series of musical pitches. But, how are those pitches understood?
In music, pitch is indicated by the first seven letters of the alphabet:
A B C D E F G
Thus, each note (pitch) on the scale will have one of these letters associated with it. Moving between these notes introduces you to the concept of changing pitch, which can be measured in half and whole steps.
Half Steps (semitones): If you start with your first finger on the 1st fret of the sixth string (low E) then move your finger up to the 2nd fret on the same string, you’ve moved up in pitch one half step.
Whole Steps (wholetones): If you start with your first finger on the 1st fret of the sixth string (low E) then move your finger up to the 3rd fret on the same string, you’ve moved up in pitch one whole step.
These terms give us a way to describe movement up and down the fretboard, particularly when we’re talking about ascending or descending scales.
Thus, scales can often be broken down into a mixed arrangement of half steps and whole steps, also called minor second and major second intervals.
Consider the following scale diagram:
I’ve circled one half step and one whole step.
Whenever they show up in scales, they make up one and two fret jumps, respectively.
If it’s a three fret jump, say the 1st to the 4th fret, we’d call that “one and a half steps.” If it went from the 1st to the 5th fret we’d say “two whole steps.” Alternatively, we can look at those longer fretboard distances in terms of intervals which go all the way up to 12 semitones or 12 frets.
You can refer to the following diagram to match up intervals with fret distance:
Scales and Keys
A musical key can be defined as the following:
The key is the root of the scale that a group of chords or notes fall into. For example, if you have three notes being played, let's say they're C, D and G, we know from the C major scale that this note sequence can be said to be in the key of C.
Thus, a key gives us a scale upon which a piece of music is based.
Let’s talk about this relationship.
What is the link between scales and keys?
We can know right away that our key is going to be one of the seven musical notes.
However, we need to keep in mind that scales are then taken directly out of that key. Thus, it could be said that any piece of music is based off a scale, which has a key. Were we to move the scale up or down the fretboard, the key would change.
Therefore the more correct explanation is that our songs have keys, which then implicate particular scales.
Scales take their letter value from the root note or “tonic” of the scale.
Once you know what scale you’re playing and in what key, you can move the scale or any segment of it to any location on the fretboard, thereby changing its key.
Chromatic Guitar Scales Explained
Western music uses 12 notes which can be referred to as “The Complete Chromatic Scale.” On a keyboard or piano this is represented by seven white keys and five black keys.
On a guitar, it’s represented by 12 frets.
The chromatic scale on the guitar can be visualized by going from the open E on the sixth string to the 12th fret (high E) on the same string, at which point the pattern simply repeats.
Those 12 notes make up the complete chromatic scale on the guitar.
Here, we only go to the 10th fret to save space in the diagram but, the concept remains intact.
All the guitar scales you will ever see are derived from this simple 12-note system. All the different sounds, melodies and music notation we get comes from a variation of this sequence.
It is made up of two types of notes:
Naturals are notes that have only a letter value (A, B, C, D, E, F, G) and neither flats nor sharps attached to them. Accidentals have a letter value and either a sharp or flat associated with it, like B♭.
Together, naturals and accidentals make up all the musical notes in existence.
Delving into the A Minor Pentatonic Scale
Though the primary intention of this article is to cover the theory and technical aspects of guitar scales, we’ll delve into some basic application here using the A Minor Pentatonic Scale as our example.
This scale is a fairly common pattern, particularly for guitar players.
We’ll cover the 10-fret model of the scale, then break it down into smaller chunks. Keep in mind that any segment of the scale can theoretically be moved to any fret.
The small blue circles on certain dots signify the root notes at different octaves (which in this case is A).
What we want to do now is break the scale down into smaller, more usable segments which can then be memorized and transposed anywhere on the fretboard.
We’ll start with the first few frets.
The first segment of the scale falls within the first three frets and the bottom four strings of the guitar. This scale should be handled in three different steps during practice:
- Memorize the pattern as it is
- Memorize the sound
- Transpose the scale to another fret
Let’s say, for example, that you wanted to move the pattern up to the 5th fret. The tab would look like this:
You’re still jumping up one and a half steps for the two lower strings and one whole step for the two higher strings. However, the scale takes on a new key as a result of moving frets.
The key of the scale starting at the 5th fret is now D.
Since we’ve already covered the process of transposing to another fret, I won’t rehash that here. However the same practicing goals apply.
The process repeats for the third segment.
10 Scales that will Improve Soloing Technique
To expand on what we’ve already covered, I've found the scales listed below to be particularly useful in the following disciplines:
- Blues improvising
- Heavy rock chord pogressions
- Modern pop and rock
- Western music’s dominant intervals and progressions
Most of today’s guitarists make their living in one of these areas or a subset thereof.
Thus, each scale has been chosen based on that assumption.
Are there others that are useful?
There might even be some that are equally useful but, you’ve got to start somewhere. Thus, we’re buying into guitar scale stocks that I believe will have the best return.
What to Think About
You’ll also want to think about how the sounds you’re hearing fit together and how the different pieces might improve your own guitar solos. Use the diagrams first, then start working through each mode without looking at the charts.
If you need a process to follow, here’s what I would recommend:
- Play through the scale several times while looking at the diagram.
- Memorize the pattern by hand.
- Play through the scale several times again without looking at the diagram.
- Once you’ve begun to recognize the sound and associate it with the name of the scale, move onto the next pattern.
All scales are in the key of C at the third fret position.
1. Basic Blues
2. Major Blues
3. Pentatonic Minor
4. Blues Variation 1
5. Dominant Pentatonic
6. Auxiliary Diminished Blues
8. Pentatonic Major
9. Pentatonic Neutral
10. Melodic Minor
Goals and Following Up
To really get to know these guitar scales you need to spend some time with them.
How much time will depend on your own practice schedule and your willingness to focus on the same sound indefinitely. It will get boring but, I’d recommend staying with each of these patterns for at least four or five days.
That’s assuming about 30 to 40 minutes of practice per day.
Here’s a possible way of scheduling this practice time:
- Monday: Basic Blues, Major Blues -- 30 minutes each
- Tuesday: Pentatonic Minor, Blues Var. I -- 30 minutes each
- Wednesday: Dominant Pentatonic, Auxiliary Diminished Blues -- 30 minutes each
- Thursday: Dorian, Pentatonic Major -- 30 minutes each
- Friday: Pentatonic Neutral, Melodic Minor -- 30 minutes each
A good goal would be to stick with this schedule for four weeks (roughly a month).
By that time each scale will have been given two hours of intentional practice and focus, at which point you should be more than ready to move on to some application of those scales.
Here are a few articles I’d refer you to for some help with applying this knowledge:
Understanding the musical concepts surrounding the guitar is tricky, since in-depth, complex music theory isn’t required to be a good guitarist. Yet we need to know enough to know why we play what we play and what all the movement on the fretboard actually means.
Guitar scale theory is a good place to start and if you have a general knowledge about how they work, you’ll be able to apply that knowledge to almost all other areas of your playing.
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