Guitar Music Theory

guitar music theoryOK, so you’ve got yourself a guitar, and you’re learning some chords. Now what? You can play a handful of songs, but you need to find a way to make those songs make musical sense, to get your brain connected to what your hands are doing and what your ears are hearing.

What you need, oh beginning guitar player, is some music theory.

Yes, that sounds intimidating, but it need not be. Luckily, the basic music theory you need for playing the guitar is a bit simpler than what you might need to cover in a college-level music theory class.  You can rest easy, most of what we’ll be talking about today is very basic. We’ll be dealing with some general guitar-based music theory today to get you started. Where you go with it from there is up to you.

The Basics

To begin with, it’s probably a good idea to get grounded in basic music theory. You ought to know the various major and minor keys, for example, and what notes come with each of those keys (the diatonic notes) and which are brought in from outside. There are many more things to know as you get started playing any musical instrument, so if you are really just beginning your musical journey, you might want to investigate an online class or two on the subject. “Beginning Music Theory” and “Music Theory: A Beginner’s Guide” are two very good places to start.

Harmony and Chords, Guitar Style

So, let’s get the big picture into focus. For guitarists, the best way to think about music theory is in terms of harmony, in terms of chords and chord patterns, and the way those chords fit together. After all, the guitar is the ultimate simple accompaniment instrument for singers, is it not? The guitar is relatively inexpensive to acquire, doesn’t take up much space, and those with an aptitude for it can begin banging out some songs within a month or so, credibly. It’s really the people’s instrument of the Western world. A great online course that is geared towards a guitarist’s point of view is called “How to Play Guitar and Really Understand Music.” It’s a good grounding in some of the same things we’re talking about today.

So, let’s talk chords. Chords come in families, groups, clans, whatever you want to call them. Some, in other words, seem to go together better than others do. Did you ever stop to think about why?

Well, this happens because of key signatures.

Who shot who in the what, now?

Yes, key signatures. Don’t be scared. They won’t bite you.

Let’s use a comparison to the piano keyboard, if you don’t mind. There are white keys and black keys. The white keys are the “natural” notes and the black keys are the sharps and flats. If you play only the white keys, you are in the key of C Major. Beginning with any C and playing the next seven notes in either direction will give you a C Major scale. This is the “do re mi fa sol la ti do” of your elementary school music class.

Now that the C Major scale is firmly in your mind, picture this: chords are formed of thirds, or groups of notes that are either three or four half-steps (three or four keys on the piano, or three or four frets on the guitar) away from each other. The chords that the C Major scale comes with are as follows: C, D minor, E minor, F, G, A minor, and B diminished. These are the diatonic chords for that key. There are no other outside notes, and no other basic chords are possible using only these notes.

And of course, these chords have certain relationships to each other. It helps to know that in music theory, Roman numerals are used to denote the chords, with the number corresponding to the position that chord’s root occupies in the scale. And the Roman numerals will be capitals for major and chords, and lower case for minor and diminished chords.

Confused? Stick with us! If you’ve got the itch for some more basic chord ideas, check out this blog post by Kasia Mikoluk, “Guitar Chord Progressions.”

So in the key of C, we have these chords to work with: I (C major), ii (D minor), iii (E minor), IV (F major), V (G major), vi (A minor), and vii (B diminished). Now, you may not have noticed, but most songs in the key of C that you may see chord patterns for have chords other than these. That’s a discussion for another day.

For now, you need to understand the basics of these diatonic chord relationships. The “big 3” chords in any key are the major chords that come naturally, the I, IV, and V chords. In this case, that’s C, F, and G. The most basic of folk and blues music comes from the relationships of these three chords. Think of “Louie Louie,” and you’ve got a song with only these three chords in it.

All of traditional music is essentially about moving from the I chord through some other chords, eventually leading to the V chord, and back to the I. Moving from V to I is known as a cadence, and while not every song has a V-I cadence, most do, and those that do not generally have a substitution for one.

The IV is usually in there along the way as well. The other chords are less significant players, but each has it’s relationship to the tonic, or I chord. Songs need to have a clear tonic to give the song a context, to make things feel grounded. Generally, songs begin and end on the I chord, so the relationships between the other six chords in that key and the I are important to learn and to be able to discern with the ear.

Now in the key of C, the V chord (G major) wants to lead back to the I chord, thanks to the leading tone of B that is in the middle of that G major chord. But other chords have less strong tendencies than the V. The ii chord (D minor in the key of C) doesn’t necessarily want to lead back to I. It can, but can also easily move to IV, V, iii, or vi. Try playing a C chord, and then move up to D minor. From there, experiment moving to F, G, E minor, or A minor. All have their own feel. The ii chord takes on a different character depending on what chord you played before and what chord you play after. You’ll get to know these connections the more you play. Perhaps the strongest and most traditional place for ii to move to, for example, is to V. Try it a few times. C, D minor, G, and then back to C. Hear what we’re talking about?

Now, all the chords in any given key have this quality as well. The iii chord (E minor in the key of C) is a strange one. It doesn’t much seem to want to lead anywhere in particular. The iii is strange that way, and has, as a result, an uncertain, sort of floating sound in its home key. Play a C, and then an E minor. Most likely, you’ll find that it might comfortably move then to F or A minor, and then somewhere else.

The IV chord can go more places than ii or iii, moving comfortably to pretty much anything in the key except vii. Very little sounds good moving to a diminished chord, and as a result, you don’t hear that type of chord much in popular music. The vii, for its part, really only likes to move to the I. That’s it. Poor vii chord. Many guitarists live perfectly normal and satisfying lives never playing diminished chords at all, and don’t miss them.

Now the V chord likes, as we said, to lead back to the I. After all, that’s what an “authentic cadence” is for the music-theory eggheads. But V can go anywhere, and in the key of C, a G major chord can go pretty much anywhere. Try moving from C (I) to G (V) and then to A minor (vi). It’s a good strategy for avoiding going right back to I, since the vi chord (A minor in this case) has two notes in common with I (C major), C and E. V can also comfortably move down to IV, and down to ii or iii. It can even move to vii, since it shares two notes in common with that chord.

The vi chord in any key is probably the most utilitarian. It can go anywhere. Just mess around with it. It is the “relative minor” chord in the context of the I, and is the most “comfortable” sounding chord in any major key.

Now if you are more advanced, too advanced for a basic discussion like this one, you might want to check out a class that will show you the world of jazz guitar theory, “Jazz Chords Introduction.” Get ready to have your mind blown by those chords!

So, one of these days, like we said, we’ll talk about the chords that come from outside the home key, the non-diatonic chords. For now, the diatonic chords and the way they move and relate to each other should keep you busy playing and listening for quite a while! Happy playing!