Just enough theory

Question: How do you stop a guitarist from playing?

Answer: Put music in front of him.

That’s me. I can’t read music and I doubt I ever will. However, over the last three years, I’ve learned just enough about music theory to be dangerous. What I’ve found is that by understanding some basic concepts, I’ve been able to find that next chord I was always searching for.

The first step in understanding is that most songs are played in a single key and that the chords come from that key. The formula (i.e. what order) you use for the chords is what make up the song. For example, blues often uses the 1, 4, and 5 chords. If you’re playing blues in E, the chords are E, A, B (or B7). The blues progression in the key of C, uses C, F, and G.

If you can understand the table below, you’ve got the majority of theory you need.

             W           W             H                W            W           W                 H
 

Here’s how to understand this table:

Intervals

Guitar frets are in half (H) step intervals. In other words, moving up one fret is moving up a half (H) step. Moving up 2 frets is a whole (W) step.

Notes and intervals

On a guitar, the open string and the 12^th fret on the same string are the same note (just different octave). If you look at the A string, the notes are:

To go from A to B is a whole (W) step. To go from A to A# (or Bb) is a half (H) step.

Also, note that for B to C and E to F, there is only a half step. There is no B^# (C^b) or E^# (F^b).

Major scale

The major scale has the following intervals, W W H W W W H. (do, rae, me fae, so la, te, do)

Applying this formula, the notes in the A major scale are: A, B, C#, D, E, F#, G#, A. As seen on the guitar the A scale looks like:

Practice tip - On any string of the guitar, apply the formula W, W, H, W, W, W, H.  In other words pick the string: Open, 2, 4, 5, 7, 9, 11, 12. You’ve just played a major scale.

Numbers for the Notes

We describe the notes in a scale by their numbers (1 – 8).

When your playing in the Key of A, A is the 1 note, B is 2… You get the idea.

Chords in the major scale

To find chords that will work in the key of A, take the root notes from the scale and use the  chord type  from the table below:  

The 1, 4 and 5 chord are major chords (A, D, E).

The 2, 3 and 6 chords are minor (Bm, etc.)

The 7^th chord is diminished

Below is a listing of the chords in the major scale for all keys. Use the table by following a row: