Banjo

February 22, 2024

Music theory and the Banjo

How much music theory do you need to know to play the banjo? Maybe none at all. I believe that the more you know, the better off you are. This is true for all of life, and also for any musical instrument.

I am writing this as I study the subject. You can look at this in two ways. One is that I am no expert, and you would be better off elsewhere. The other is that I am going to try to explain it from the point of view of someone grappling with it for the first time.

Whatever the case, I find it extremely useful (for myself anyway) to try to summarize what I think I have learned and express it in my own words.

As with any discipline, there is jargon and having precise definitions of terms can be important, if not vital.

Some references

Here are some online links. I don't know yet how good (or bad) they are. Many get started with some assumption about what you already know.

First steps

Grab your banjo and look at it. Mine has two dots marked on it 12 frets down the neck. This number 12 is important. If you fret a string at this position and pluck it, you will get the same note as the open string, but an octave higher.

So the way the frets on a banjo are engineered, an octave is broken into 12 equal steps. As it turns out the music people call these half steps.

Now as you probably know, the music people use 7 letters to give names to notes. A B C D E F G At this point you ought to be wondering what connection there is between these 12 equal divisions of the octave and these 7 letters. The story is complex (and in my opinion, weird).

Now some notation. We can talk about a note that is a half step higher or lower than a note that gets a plain old letter. A note that is a half step higher is called a sharp and gets the # symbol. A note that is a half step lower is called a flat and gets the "b" symbol. Actually the "b" is written in a sort of italic, but we will just use a plain old "b" in this essay.

With this notation, we can now give names to all 12 notes in an octave:

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

It seems conventional to use the "sharp" names rather than equivalent "flat" names. But it is important to know that A# amd Bb are equivalent (are the same sound). Also note that BC and EF are special -- you don't get a B# between B and C, nor do you get an E# between E and F.

Don't ask me why this is the way it is. At this point I just point to tradition and wait until I learn more to perhaps get deeper understanding. Weird as all this may seem, realize that this is how musicians have been doing business since the time of Bach, Mozart, and Beethoven. At least this is true in the western world. If it was good enough for them, it ought to do for us.

Do Re Mi ...

Here we have the 7 basic notes, but starting with "C", so:

Do = C
Re = D
Mi = E
Fa = F
So = G
La = A
Ti = B
Do = C  (back where we started)

This is also called the "diatonic scale" -- don't ask me why -- we are getting ahead of ourselves.

The Banjo in G tuning

People like to talk about the "fretboard" and let's make a diagram for the first 4 strings.

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

With some study of this, we could play scales. I put my "**" notation on frets 3 and 5 as that is where my banjo has dots.

Why does the G major "key" contain F sharp?

I am starting to incorporated playing scales into my practice, and immediately I notice that plain F does not sound right. And indeed, it is F sharp (F#) that belongs.

It turns out that all the keys other than C major contain some sharps. That is how it is, but why? We may never answer why. That seems to be the nature of a lot of music theory, never mind "why", this is how it is and this is what works.

So a key contains 7 notes, with the pattern: R W W h W W W h.

In this representation, "R" is the root note, "W" is a whole step, and "h" is a half step.

So for G major and C major, we get:

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

Here I represent the notes that are "h" from the previous one by surrounding them with parenthesis.

This just pushes the question deeper. Why the pattern R W W h W W W h ?

To use actual musical jargon, the notes that are a full step from the "root" note (called the "Tonic) are called "Tones". Notes that are a half step are called "Semitones". This doesn't explain anything but at least introduces us to the conventional lingo.

A way to think about it is to start with the C major scale and the pattern of intervals in it. We start with the C major scale because it doesn't have any sharps or flats in it. If we construct another scale starting on a different note, we want to maintain the same pattern of intervals, and that involves some sharps (or flats) on any scale other than C major.

At this point many texts introduce what is called the circle of fifths. This gets us into deeper water than I am willing to wade into just yet.