Why do we need Guitar Chord Theory

Guitar chord theory is not for everyone. In an effort to progress as a proficient guitarist, we must press forward and learn new and exciting things.  The beautiful thing about guitar chord theory is that everything you learn is based directly on something you’ve already learned. So it tends to be a very linear learning process which is great because it simplifies things for us.

Guitar chord theory

Guitar chord theory- Constructing 7th chords

In another article I wrote about constructing a major chord from the major scale.  In this article, I will explain how to construct 7^th chords using the exact same method of guitar chord theory.  As with every other chord construction, it begins with the major scale. So to keep things simple we are going to use the Cmaj scale as an example. The reason for this is because the Cmaj scale has no sharps(#) or flats(b). So if you recall the major chord in guitar chord theory is constructed from the 1^st, 3^rd and 5^th notes of the major scale.  It is a 3 note chord which is also referred to as a “triad”.  The C major scale is:

C  D  E  F  G  A  B

The Cmaj chord consists of the 1^st,3^rd and 5^th notes (C,E and G). So now that we have mastered that, we are going to learn how to construct 7^th chords.  Unlike major triads, 7^th chords are made up of 4 notes.  There are many different types of 7^th chords but we are only going to discuss two of them.  The major 7^th (abbrà maj7) and the Dominant 7^th (abbrà7).

After going through the process of constructing a major chord using guitar chord theory, you can see how simple this is, and that holds true for 7^th chords as well. Let’s start with the major 7^th chord, and pay close attention! Take your major chord (triad) and add the 7^th note.  Did you get that? Add the 7^th note to a major chord and you have a major 7^th.  Let’s see how that looks using our Cmaj scale.

C  D  E  F  G  A  B

The major triad is C, E and G (1,3 and 5).  Now add the seventh note, which in this case is a “B”.  So a Cmaj7 chord is made up of a C,E,G and B. Too easy!

Guitar chord theory- A closer look at the Dominant 7^th chord

Let’s now take a closer look at the Dominant 7^th chord.  In our case it will be the C Dominant 7 or very simply C7. To construct a dominant 7^th chord we simply take the major triad and add a flattened 7^th.  Whoa! That sounds complicated! Not at all.  There are two changes we can apply to a note.  We can flatten it (move it down one semi-tone or half step), or sharpen it (move it up one semi-tone or half step). So here it is in a nutshell.  The 12 tones are:

A  A# B  C  C#  D  D#  E  F  F#  G  G#

To flatten, we move one note to the left (i.e. a flattened E is a D#)

To sharpen a note we move one note to the right (I.e. a sharpened C is a C#)

This is even easier to understand on a guitar because a half step is always going to exactly one fret!

So to complete the example a C7 is the 1^st, 3^rd, 5^th, and 7b(flattened 7^th) which translates to:

C,E,G and A# (or as Bb they are the same note).

I hope by now you are starting to see how easy it can be to learn guitar and music theory at the same time. Now go and practice! This concludes this lesson on guitar chord theory.