Today we are going to talk about a fundamental concept of music theory: The circle of 4ths and 5ths
The circle of 4ths and 5ths is a very easy method to learn the scales of western music. Take a look at the picture below
We begin at C. If go clockwise, we are moving in 5ths. A 5th is 7 semitones. If we go counterclockwise we are moving in 4ths. A 4th is 5 semitones. Now, if we move in 5ths, we get the scales that have sharps. If we move in 4ths, we get the scales that have flats. Take a look at that picture.
In right you see the sharp scales, in the left the flat ones. Theoritically, we can create all scales with flats and sharps, but after a certain point, we get double sharps and flats, which make it cumbersome to deal with. In the bottom, we have three scales that are enharmonic. This means that they can be written either with flats or sharps, but they are the same thing.
Below each major scale, you see the relevant minor scale. This is the minor scale that contains the same sharps and flats as a certain major. To get the minor of a major, simply move down 3 semitones (that is a minor third).
The circle of fiths and fourths is one of the first thing one learns when he starts studying music theory. The reason is simple enough. You have to know all the scales. When you see a musical score, you see at the beginning the sharps and flats it uses. You have to be able to determine at once the key the piece is in. When you improvise, you have to do so on a scale. This means that you have to practice scales all day long so that you know them by heart.
However, the circle of 5ths and 4ths offers a nice way of getting harmonic progressions. Progressions in 5ths are very common in classical music. Well, not actually harmonic progressions, but modulations. You see, two scales a 5th apart, are only different by one sharp. For example C has no sharps, and G has only one. This makes it simple to change from one scale to the other.
On the other hand, in jazz, the circle of 4ths is the most common progression. It creates a feeling of a never-ending progression. Actually, if you want to improvise and you have no ideas, then just play the circle of 4ths from any key you like . It’s one of the most easily used, catchy and useful ideas ever. You can actually write whole songs based on these two progressions.
Well, that was it for today! These are the basics of the circle of 5ths and 4ths. Until next time, keep studying and be creative!