The good news about Bluegrass and Dobro is that they do not require an extensive amount of musical theory to understand and appreciate them. But we all know that some notes go together better than others, and it is a basic understanding of the underlying music theory that will let you predict and find these combinations.
The most basic of these principles is understanding scales.
Types of ScalesThere are all kinds of scales and modes, but in Bluegrass, we rely almost exclusively on four:
- Chromatic scale
- Major scale
- Minor scale
- Blues scale
These scales apply to all types of music and all instruments, but I will discuss them in the special context of the Dobro.
This section will cover the chromatic scale and the major scales. Part 2 will cover the minor scales and the blues scale.
Chromatic ScaleThe chromatic scale is the complete inventory of all the notes you have at your disposal. It is your toolbox from which all other scales and chords are made; therefore, you need to know it so you know what you have to make music with.
Notice, I said "it." There is only one--hooray! That makes sense, since it contains all the notes there are, how could there be more than one?
In Bluegrass, as in all Western music, notes are arranged in what we call half steps. Physically, every fret on a guitar, mandolin, or banjo is a half step. So to play the chromatic scale, just start on an open string and start going up the fret board one fret at a time.
Let's look at the chromatic scale starting on G.
If you pluck the 3rd string on the Dobro, here is the chromatic scale.
Notice that notes are named with the letters A through G. The # symbol means "half step above." One interesting thing is that most letters have a half step between them and the next higher letter with the exception of B and E. B goes directly to C and E goes directly to F. Don't ask me why because I don't know--most importantly, I don't need to know in order to make good musical decisions.
Major ScaleIf you ever heard someone sing the scale, as in "do-re-mi-fa-sol-la-ti-do," they were singing the major scale. We talk about a major scale as being in some key, and the key is the name of the note we start on (often called the root). Regardless of where they start, all major scales have the same pattern:
Two wholes and a half, three wholes and a half.
In other words, a major scale starts on a note, then goes up a whole step (two half-steps) then another whole step, then a half step, whole step, whole step, whole step, and lastly, a half step.
Here is the scale of G Major, compare the steps with the chromatic scale above:
So we start on G and go two half steps (G# and A) and that leaves us on A. Take another two half steps (A# and B) and that lands us on B. Now take a single half step and that takes us to C. (Remember this is one of the two exceptions and there is just a half step between B and C.) The next three whole steps land us on D, E, and F# respectively. Then the last half step is from F# to G. If you started on the 3rd string open, you should have ended on the 12th fret.
I have included a set of scale exercises in G that shows the various ways you can achieve this basic sequence for G.
The same pattern (two wholes and a half, three wholes and a half) can be applied to any note in the chromatic scale as a starting point. That could be a lot of scales, but most bluegrass songs will be in the key of G, C, D, or A.
Here are those scales; look at the chromatic scale above to verify that they all follow the same pattern:
C Major: C-D-E-F-G-A-B-C
G Major: G-A-B-C-D-E-F#-G
D Major: D-E-F#-G-A-B-C#-D
A Major: A-B-C#-D-E-F#-G#-A
Notice that in this order of the keys, each one adds a sharp, while keeping all the previous sharps. C--no sharps; G--one sharp: F#; D--two sharps: the F# and now a C#; A--three sharps: the F# and C# and now a G#. Notice that the extra sharp that gets added is the 7th note in the scale, which is always a half step below the 8th note. (Remember the simple phrase Country Gentlemen Don't Argue to recall this order of the keys.)
It is useful to know the notes in each of these major scales for two reasons:
- Most of the melody notes in a bluegrass song will be based on the notes of the scale. Knowing the notes of the scale in the key you are playing will help you predict where a song is going and will help you define a break (solo) for when someone yells "Dobro" in the jam.
- The notes of a scale combine in a special way that defines the most used and useful chords in that key (more on that when we talk about chords).