Basic Key Signatures and the Circle of Fifths
This page presents the basic information on Key Signatures and the Circle of Fifths. We will explore the "why" of this in the next few weeks. For the moment, simply memorize this practical concept.
We organize music in a cycle of fifths, with the notes associated with the sharp keys going around to the right, and the notes associated with the flat keys going around to the left. They meet in the middle around the enharmonic equivalence Gb and F#. (Notice that this is directly across from C and also a tritone (augmented fourth / diminished fifth).
Your goal here is simple. Simply memorize the cycle of fifths. I recommend you do so either at a keyboard or with Practica Musica open, so you can play the notes as you memorize the pattern.
The minor keys inside the circle refer to the relative minor keys. This will be covered later on in the course. For the purposes of this chapter, simply learn the cycle on the outside of the circle.
Key signatures around the sharp side of the Circle
Notice that as we go around the circle to the right, we must continually raise the leading tone to produce the proper major scale, which is a series of steps in the following order (expressed in the key of C):
Whole (C-D), whole (D-E), half, (E-F), whole (F-G), whole (G - A), whole (A-B), half (B - C).
- From G to G, all the natural notes follow the pattern except the last one. The F needs to be raised to produce the major second between E and F# and the minor second (half step) between F# and G.
As you go around the cycle, the pattern that emerges is that the sharp from the previous key is retained, and then the seventh step, which is natural, is raised to produced the raised leading tone.
This results in the following scales:
G A B C D E F# G
D E F# G A B C# D
A B C# D E F# G# A
B C# D E F# G# A# B
Notice how in each case the previous sharped notes are maintained, and the seventh step of the scale is raised one half step. You should play these on the keyboard to ascertain that, indeed, this produces a major scale.
Key signatures around the flat side of the Circle
As we go around the left side of the circle, a similar pattern emerges. We want to produce this same series of whole and half steps expressed again in the key of C:
Whole (C-D), whole (D-E), half, (E-F), whole (F-G), whole (G - A), whole (A-B), half (B - C).
From F to F, we can observe that the leading tone is OK: we have a half step from E to F, so the leading tone can stay natural. However, we will observe that scale steps 3 to 4 (A to B) is a whole step and scale steps 4 to 5 (B to C) is a half step. It needs to be the reverse. By flatting the fourth step (in this case, flatting the B), the correct pattern emerges:
F G A Bb C D E F
Now, as we go around the cycle of fifths along the flat side, we follow the same pattern. We keep the flat from the previous key and add the flatted fourth. The resulting pattern is:
Bb C D Eb F G A Bb
Eb F G Ab Bb C D Eb
Ab Bb C Db Eb F G Ab
Db Eb F Gb Ab Bb C Db
Notice how in flat keys, the leading tone is always a natural note, leading up to the flat note that forms the root of the key.
The key signatures for these keys are always notated as follows. Memorize this pattern and this ordering of sharps and flats. Again, ignore the minor indications for now and focus on the first portion of the slash, which indicates the major key.
The basic rule for identifying these signatures is:
- For sharps: take the last sharp to the right and go up one.
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- For flats: the key is the second to the last flat from the right. (This doesn't apply for F; you just need to memorize that one flat is the key of F.
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- For the relative minor: once you find the major key, go down three scale steps.