How Key Signatures Work
It is important for you, as a guitar player, to know about key signatures and how they work. The more you know about key signatures the easier it will be for you to figure out songs and improvise over those songs.
You might have heard of the cycle of fourths and the cycle fifths. If you haven’t we will talk a little bit about them first. A cycle of notes is a pretty simple concept. Let’s start with the cycle of fourths. Start on any note, B for example, and then count four notes away from B. That note would be an E. Count four notes away from an E to an A note. Continue counting four notes away until you come back around to a B note. That is a cycle of fourths. Here is the entire cycle BEADGCFB.
A cycle of fifths would be the exact same thing but you would just count five notes away from whatever note you start on. Let’s start on an F note. A cycle of fifths would be FCGDAGBF.
Now that you know your cycle of fourths and fifths you can use this information to find any key signature you like. Let’s start out by learning how to use the cycle of fourths to determine what notes are flatted in any given flat key.
Take your cycle of fourths, BEADGCF, and start on the C note. The key of C has no sharps and no flats so we will start there. Move on to the next note in the cycle, an F note. The key of F has one flat. To find out which flat the key of F has just go back to the first letter in our cycle of fourths. That letter is a B, so the one flat in the key of F is a B flat or Bb. Now, move on to the next note in the cycle after the F. That takes us back around to the beginning of the cycle to a B, but we wouldn’t use a B for our key, we would use a Bb. The key of Bb has 2 flats and those flats are Bb and Eb. Keep this going with the keys of Eb, Ab, and so on.
The cycle of fifths, FCGDAEB, can be used to find all of the key sharp key signatures. Remember that C has no sharps or flats so start with that key. Go to the next note in the cycle, a G note. The key of G has one sharp. That sharp is the first letter in the cycle of fifths, an F#. Move on to the next note in the cycle after G, a D note. The key of D has two sharps, F# and C#. Continue on to the key of A and E. The key of A has three sharps, F# C# and G#, and the key of E has four sharps, F# C# G# and D#.
Learning how key signatures work can be difficult at first but if you work hard it gets easier. Here is a video that will help you understand key signatures a little more. For more music theory lessons you can check out these online guitar lessons.
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