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Learning music theory is less common with guitar than it is with other instruments. It’s absolutely possible for guitarists to reach extremely advanced technical ability levels while knowing next to nothing about music theory. However, for a working musician it’s an essential skill. Transcribing your songs, using music software, teaching, professional composing, or directing the Philharmonic orchestra at the rehearsals for your Death-Metal-Band-Plus-Live-Orchestra-Tour are all nearly impossible tasks without at least a basic working knowledge of music theory for guitar.
So let’s start at the very beginning.
The Notes and Chromatic Scale
In these note names the # means “sharp” and the b means “flat.” You may have previously heard note or chord names like “F sharp” and “B flat.” This is why.
So, for example, the note between C and D is C#/Db (C Sharp or D flat). This is just one note, with two possible names. Why you’d opt for one of the names in particular comes much later. For now, either name is fine.
These two possible names for the same note are what we call enharmonic equivalents. There is no difference in pitch/sound, or position on the fretboard. C# and Db are the exact same note. It’s just like ordering “chips” in a British restaurant and “fries” in an American restaurant. Different word, but you still end up with the same thing!
The exceptions: You may’ve noticed that E goes straight to F, and B goes straight to C. There is no E#/Fb or B#/Cb.
Imagine the keys on a piano keyboard (or better still, go and play one). These enharmonic equivalents–sharps or flats–are all the black keys on the keyboard. You’ll also see that indeed we go straight from E to F, and B to C, with nothing in between.
TIP: Relating things back to the piano (or keyboard) is extremely useful when learning music theory. If you don’t have one, see if you can get your hands on one from a friend, relative, or dusty attic. Or, you can pick up a basic new one pretty cheaply these days.
Semitones and Tones
There are two terms you need to learn now, if you don’t already know them. They are “semitone” and “tone.”
If you ever struggle to remember which is which, the clue is in the prefix “semi” which means “half.” A semitone (1 step) is half of a tone (2 steps).
Still with me?
The Major Scale
The Major scale (the Do-Re-Mi scale) is the foundation of modern Western music. It is constructed from a starting note using a series of moves or steps, all of which are either a semitone or a tone.
The Minor Scale
The equally important second component of music theory is the minor scale. Simply put, music based on minor scales is often described as sounding “sadder” than music based on Major scales. While this description is quite general and basic, it sums the situation up pretty well at a surface level.
Here’s the formula for constructing a minor scale: T ST T T ST T T
So, the A minor scale would be:
A (tone) B (semitone) C (tone) D (tone) E (semitone) F (tone) G (tone – back to A)
Again, this is entirely formulaic, so although an E minor scale will contain different notes than this, and the G minor scale different notes again, they are all formed in the same way: by taking the tonic/root note then moving in tones and semitones to form the scale.
Chords and Keys
What’s the difference between a scale and a key?
As you just learned, a scale is a sequence of notes formed using a recognized formula.
A key is a sequence of chords formed from a scale.
A “key” is a group of 7 chords that are related to each other and deemed to “go well together.” These 7 chords are formed from the 7 notes in a scale, by assigning a chord type to each step of the scale. This sounds complicated, but is very simple. Let’s review some examples to help you make sense of it.
Major Key Formula
In a key of chords, the Major key formula will always be as follows:
Chord 1 = Major
Chord 2 = minor
Chord 3 = minor
Chord 4 = Major
Chord 5 = Major
Chord 6 = minor
Chord 7 = diminished
So the key of C Major (the 7 chords ‘belonging to’ the C Major scale) contains the following chords:
For now, you don’t need to worry about why these chords are Major, minor, or diminished. Those are topics for a later, slightly more advanced music theory course. However, the answers are out there and easy to find if you’re curious and would like to explore further on your own
Additionally, you’ll notice that we capitalize the “M” in Major, but a lower-case “m” for minor and a lowercase “d” for diminished. This is done on purpose, but you don’t need to worry about that right now.
TIP: Do make sure you know at least one way to play a diminished chord so that, for the time being, you can practice it and use it in your playing.
Remember: This is a formula and the formula stays the same in all Major keys.
Once you have all the chords in the key of E Major, guess what? You now have all the chords you need to write a song in that key! If you know how to play these chords, go ahead and give them a try. Practice playing some of the chords together and see how they sound (some will sound better together than others).
Minor Key Formula
In a minor key the formula is:
Chord 1 = minor
Chord 2 = diminished
Chord 3 = Major
Chord 4 = minor
Chord 5 = minor
Chord 6 = Major
Chord 7 = Major
So the key of A minor (the 7 chords ‘belonging to’ the A minor scale) contains the following chords:
Remember: This is a formula and is the same in all minor keys.
Summary of Key Points
- # = Sharp
- b = flat
- C# and Db are alternate names for the same note, or “enharmonic equivalents”
- A semitone is one step/fret/piano key
- A tone is two steps/frets/piano keys
- Major scale formula: T T ST T T T ST
- Minor scale formula: T ST T T ST T T
- Chords in a Major key: Major – minor – minor – Major – Major – minor – diminished
- Chords in a minor key: minor – diminished – Major – minor – minor – Major – Major
So, there we go! That’s the end of The Very Basics of Music Theory for Guitarists. Starting with all the notes in existence, to theory-based songwriting via tones, semitones, scales and keys. One very important thing to remember is that music theory is a HUGE subject full of details, examples, rules and exceptions. It is absolutely OK to go away from this post having only understood 65% of it. Learning music theory for guitar is an ongoing process of gradually widening your knowledge, and learning and re-learning things as they continue to come up. The best thing you can do is to take that 65%, and go and apply it now!
If you have any questions, please let me know down in the comments below.
Further Reading: Recommended Books on Music Theory for Guitarists
Have a desire to learn more about music theory for guitar? Here are 4 good books that’ll help you take your music theory knowledge to the next level:
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