Music Theory You Need, Especially if You Don't Read: Guitar Chords

As we have outlined music theory for non-reading musicians in our previous article, you have learned your key signatures and the diatonic scales and chords that comprise them. In this article, we will use that knowledge to find our way around the fretboard, creating new chords from scratch in seconds. Let's get started!

How to Build Chords from Scratch

If you have been playing guitar for a while, you probably sat down with a chord chart at some point and memorized "all the chords," just like Guitar George. Of course, in reality there are thousands of chords you've probably never even seen! Fortunately, just as there were shortcuts to learning your diatonic scales and chords, so too there are easy ways to modify the chords you already know to create practically infinite variations. See how many of these standard chord forms you already know.

Chances are good that you know most of them (if not, you really need to learn these). You will notice these are all barre chords that you can transpose to any key by sliding them to another fret. However, the really important part is that the scale intervals which make up the chord are notated in each fingering. Take a moment to familiarize yourself with the location of each interval within the form. You will see that it is common to have duplicates of the Root (1st) and 5th intervals, but not the 3rd. This is because the 3rd is a very strong interval that need not be duplicated. You can figure out the intervals of any chord you know by playing the diatonic scale beginning at the Root and counting your way up to the note you are fingering.

Each of our sample chords is a major triad (Root, major 3rd, 5th). These are very useful, but what if you wanted a minor triad (Root, minor 3rd, 5th) instead?

As an example, consider the first form; the major 3rd is located on the B string. Since a minor 3rd is a half-step down from a major 3rd, all you must do is slide that interval down one one fret, and now you have a C minor triad. This commonly requires you to devise a new fingering. If you wanted a C(sus2) you could lower the minor 3rd another half-step. And if you were looking for a C(sus4), you could simply raise the major 3rd a half-step. For practice, look at each diagram and figure out where the 2nd, minor 3rd, major 3rd, and 4th are located. You can calculate b5, 6th and augmented chords by adjusting the 5th as well. Warning: if you alter the 5th, make sure you alter it every place it appears!

"Great! But I already know my triads. How do I find the rest?" 

This is where the extra Root positions become useful. A major seventh is a half-step down from the octave (which is the Root), so drop that finger one fret and you have a major 7th chord. Avoid altering the root, which can make the chord ambiguous. A dominant 7th or minor 7th is two half-steps down from the octave. Extended chords like 9ths, 11ths, and 13ths can be calculated by counting up from the octave. Once you grasp the concept, you'll never struggle to come up with a Cm(maj7th) chord on the spot; just play a Cm and drop the octave one half step (note the illustration shows fingering, not intervals, and the barre would be on the 3rd fret).

The more familiar you become with the intervals and variations of each of your favorite chord forms, the more creative ideas you will come up with in your playing. Jimmy Page's bluesy comping part on the verse of "Rock and Roll" features only the 3rd and 7th of the chord, juggling them to produce an A7 to D7 change merely by sliding the diad from the 5th fret to the 4th fret. This also illustrates a great jazz trick for creating middle voicings. Since the Root and 5th are usually carried elsewhere in the band, you can sometimes omit them, so long as you include the 3rd and any other extended intervals.

Do some music theory practice and create as many chords as you can based upon the basic barre chord forms. In our next article, we will discover how to create arpeggios using the same approach and we will learn the Nashville Number System. Good luck and study hard!

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