The Circle of Fifths it is nothing more than a sequence with distance intervals of perfect fifths.
For example, the sequence: C – G – D – A – E – B is made by intervals of perfect fifths, therefore, it is part of a circle of fifths. You can see as B is the fifth above E which is the fifth above A and so on.
Nice, but what is the use of it?
How to use the circle of fifths
- The C major scale doesn’t have any accident (any note has sharps or flats).
- The G is one fifth above C, and the G scale has one accident, the note F#.
- The D is one fifth above G, and the G scale has two accidents, F# and C# notes.
The main point is: in each fifth we will have one more accident in the next scale. This is useful mainly for keyboard and piano players, because each major scale has a different drawing, and the number of accidents will say how many black keys the scale will have. You can see below a table with the accidents in each major scale:
Ok, but this is not the only use of circle of fifths. It is interesting to observe that the V7 dominant chords can be “stacked” one after other, creating a sequence of resolution grounded in fifths. When this happens, these dominants receive the name “Extended Dominants”.
Circle of fifths forming extended dominants
Look at this example:
| A7 | D7 | G7 | C |
You can see that in this sequence, A7 was solved in its tonic (D), even though this D didn’t have tonic function, but a dominant function (D7), solving in G. In the same way, G7 didn’t work as tonic, bus as dominant solved in C. Therefore, we had a sequence of Extended Dominants; and looking from left to right, the fifth degree of C is G, the fifth degree of G is D and so on. In other words, we make a circle of fifths.
Pentatonic scale and the circle of fifths
Not everyone knows, but the pentatonic scale comes from a circle of fifths! See the sequence C – G – D – A – E (circle of fifths starting in C). Now compare with the notes of the pentatonic scale of C major: C, D, E, G and A.
As we can see, when we take the first five notes of a circle of fifths, we are creating a pentatonic scale.
Circle of fourths
Very well, till now we only talked about circle of fifths; but what about the Circle of Fourths? It is nothing more than a circle of fifths seen in the opposite way. See the previous sequence: C – G – D – A – E.
This sequence if saw from the left to the right has the intervals of fourth. In other words, the circle of fifths is the inversion of the circle of fourths and vice-versa.
Ok, let’s finish than this topic drawing the complete circle of fifths. We will make a circle and will put in it all the 12 notes spaced by intervals of fifth:
Notice that, in clockwise sense, we have the circle of fifths, and in the counterclockwise sense, we have the circle of fourths.
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