keys signatures explained
The circle of fifths is a handy tool for organizing the 12 possible Major scales into what is called KEY SIGNATURE.
In the Major Scale Lesson, we learned that “key” refers to the starting note (root) of the scale. “Key signature” simply refers to the number of sharps or flats that occur in each key. No two major scales will contain the same number of sharps or flats, so scales can be easily organized by key signature.
Let’s take a look.
As we learned in the Major Scale Lesson, the C Major scale contains no sharp or flat notes – C D E F G A B. This is the only Major scale with only natural notes. All other keys will have a varying number of sharp or flat notes. Each key has a unique key signature.
If we build our next scale starting with the 5th note of the C major scale, we get the G Major scale – G A B C D E F#. Notice that the G Major scale has one note that is sharp (F#).
Now, lets build a third scale starting from the 5th note of the G Major scale. That will give us the D major scale – D E F# G A B C#. Notice that we now have two notes that are sharp (F# and C#).
If we build a fourth scale from the 5th note of the D Major scale, we get the A Major scale – A B C# D E F# G#. As you’ve probably guessed, the A Major scale has one more sharp than the D Major scale.
That’s how it works.
If you build a Major scale from the 5th note of another Major scale, the new scale will have one more sharp than the scale you started with.
That’s where the “5ths” in the circle of 5ths comes from, but what about the “circle” part? The circle comes from the fact that if you continue to build a scale from the 5th note of the previous scale, you will eventually wind up right back at the beginning, C Major:
D is the 5th note of G Major.
A is the 5th note of D Major.
E is the 5th note of A Major.
B is the 5th note of E Major.
F# is the 5th note of B Major.
C# is the 5th note of F# Major.
G# is the 5th note of C# Major.
D# is the 5th note of G# Major.
A# is the 5th note of D# Major.
F is the 5th note of A# Major.
C is the 5th note of F Major.
We’re right back where we started, as if we traveled in a circle.
Now, one of the conventions of key signatures is that a proper key signature does not mix sharps and flats. You have one or the other, not both. Another convention is that the letter name for each note can only be used once. These two conventions present us with a problem.
Once you get to a certain point within the circle, it becomes impossible to observe these two conventions without considering the note F to be E# and the note C to be B# or resorting to the awkward designation of DOUBLE SHARP. (Denoted by x, a double sharp note is equivalent to the note one whole-step higher than the letter name being used. Cx is the same pitch as D.)
Let’s look at the key of F#:
F# G# A# B C# D# E#(F)
In order to avoid using both F and F# in the key signature, we have to “bend” the rules and name F as E#.
The convention of not using the same letter name twice is a hold-over from written music notation. See this lesson for an introduction to written notation. As you can see from that lesson, each letter name is given a line or a space on the staff. It would be very awkward trying to write both F and F# into the same key signature.
Now, once you get to the key G# in the circle of fifths, the dreaded double sharp appears:
G# A# B#(C) C# D# E#(F) Fx(G)
At this point, things are getting out of hand. So, what would happen if, instead of trying to use a G# scale, we were to use Ab instead? (Remember that G# and Ab are the same note.)
Let’s try it:
Ab Bb C Db Eb F G
Hey, that’s a lot better than that G# monstrosity!
So, let’s take a look at key signatures with flats instead of sharps.
If we go back to the C Major scale (C D E F G A B), but instead of going to the 5th note, we go to the 4th note to construct our next scale, we get the F Major scale- F G A Bb C D E. Notice that the key of F Major has one flat.
If we build our next scale from the 4th note of the F Major scale, we get the Bb major – Bb C D Eb F G A. Notice that we now have two flats.
It’s the same pattern all over again.
If you build a Major scale from the 4th note of another Major scale, the new scale will have one more flat than the scale you started with.
And once again, if you keep going, you’re going to end up right back at C:
C F Bb Eb Ab Db Gb B E A D G C
Let’s reverse the order of those notes:
C G D A E B Gb(F#)…..
Hey! Wait a damn minute! Isn’t that the same order we had before, when we were working the sharps? (Go back and take a look.)
It sure is.
If we take our original circle of 5ths and change each sharp to its flat equivalent we get this:
C G D A E B F#/Gb Db Ab Eb Bb F C
Now, since we’re calling this a circle, let’s look at it that way:
C is at the 12:00 position, because the key of C has no sharps or flats.
If you travel clockwise around the circle to the 6:00 position, each successive key has one more sharp than the preceding key.
If you travel counterclockwise to the 6:00 position, each successive key has one more flat than the preceding key. Moving counterclockwise around the circle is sometimes referred to as the circle of 4ths and also referred to as “back-cycling” through the circle of 5ths.
Now, let’s take a look at F#/Gb:
F# G# A# B C# D# E#(F)
Gb Ab Bb Cb(B) Db Eb F
It makes no difference whether you use sharps of flats with this key. Both give you the same result. If you use sharps, you end up having to refer to F as E#. If you use flats, you end up having to refer to B as Cb. It’s pretty screwy, but there’s nothing to be done about it.
Here’s a handy sing-song for remembering which notes are sharp or flat in each key:
Sharps = Father Charles Goes Down And Ends Battle.
Flats = Battle Ends And Down Goes Charles’ Father.
Each successive key not only adds a new sharp or flat, but keeps the sharps or flats that were present in the preceding key.
Moving around the circle clockwise yields G (Father), D (Father Charles), A (Father Charles Goes) etc… The key of G has one sharp, which is F. The key of D has two sharps, which are F and C. The key of A has three sharps, which are F, C and G etc…
Moving around the circle counterclockwise yields F (Battle), Bb (Battle Ends), Eb (Battle Ends And) etc… The key of F has one flat, which is B. The key of Bb has two flats, which are B and E. The key of Eb has three flats, which are B, E, and A etc…
The circle of 5ths is very easy to visualize on the fingerboard:
The circle of 4ths is just as simple:
In each case, you start with C, and add a sharp or flat for each successive key. It doesn’t get much easier, folks.
The circle of fifths falls into the category of “something handy to know but not something that you can really practice”… that is, until you begin analyzing songs and/or writing your own songs. Many common chord progressions follow the circle of 5ths. The more familiar you are with this device, the easier you will be able to spot it’s use within a song.
One use for the circle of 5ths in a compositional sense is as a key changing device. Changing the key signature in the middle of a piece of music is called MODULATION. The smoothest modulation occurs between keys that have only one note difference between the two keys. If you’ve been paying attention, you should realize that this is exactly how the keys are organized with the circle of fifths.
A good way to practice modulation, utilizing the “circle”, is to pick a position on the guitar neck and “run the scales” through the circle. Without moving up or down the fingerboard more than one fret, you should be able to pick out each successive sharp or flat key and play that Major scale.
If you are soloing over a chord progression that suddenly shifts to a new key, the ability to quickly change to the appropriate scale is a must. You won’t always have the luxury of shifting your hand position in order to change to a new scale.
Learn your scales.
Learn your fingerboard.
That’s the only way.
- Guitar Theory
- Know Your Notes
- The Major Scale
- The Circle of Fifths
- Triad Inversions
- The Chord Scale
- Relative Major and Minor
- Pentatonic Scales
- 7th Chords
- Fingerboard Organization
- Melodic Patterns
- Guitar Theory