But thats not why the Co5 is important, thats just how it is arranged. One major advantage is the ability to know how many sharps and flats are in a key. When I first touched music theory back in middle school we had to memorize the sharps and flats, no rhyme or reason. Using the Co5 they are all lined up for you. C = n/a, G = 1#, D = 2#, A = 3#, E = 4#, B = 5# (Cb = 7b), F# = 6# (Gb = 6b), C# = 7# (Db = 5b), Ab = 4b, Eb = 3b, Bb = 2b, F = 1b. Now you can believe me on this or write out that scale using WWHWWWH and count the sharps or flats for that key. Like I said, this is a lot to learn at once, so I have split it into sections. Each section has a Co5 diagram that we used. Learn each one of those diagrams so you can write all of them down. At the end of the chapter all the Co5 diagrams combined to one comprehensive circle.
The Co5 can also show us the order of sharps and flats. The order or sharps ( notice the diagram mapping these out on a Co5) are F# C# G# D# A# E# B#. You might ask what the order of sharps has to do with anything.Well what it does for us is tell us what sharps happen when. For example, D major has 2 sharps, F# and C#. Write out the scale for D, D-E-F#-G-A-B-C#-D. Using the order of sharps you can see that, yes the first two sharps are F# and C#. E major has 4 sharps, without writing the E scale out, tell me what the sharps will be. F# C# G# D# is the correct answer, write out the scale to prove it.
Using the last couple lessons on the Co5 can be very beneficial when it comes to writing scales. You have 5 secs to write out A major. Did you get it? Most people couldn't. Try this, ignore all sharps and flats, write down all the notes starting with A. A B C D E F G A. Thats just a bunch of notes ( A Aeolian Mode actually but thats later ). The Co5 shows us that A major has 3 sharps. Using the order of sharps we find that A major has a F# C# and a G#. So take the notes we wrote out and sharp the F C and G. Don't believe its that easy, test it out. Write out A major, (WWHWWWH) and compare. As you will see, they are the same. Learning the sharps and flats we can write out any scale with hardly any effort. Not that I'm lazy or anything, but if I'm on stage and we decide to change keys or modes mid song, I need to be able to find the right note to play. I don't have time to sit down and WWHWWWH the scale. Key of E, 4 sharps, F# C# G# D#, every other note is natural, thats all there is to it.
On to the flats, take the order of sharps and reverse it, BEADGCF, then switch the last two, BEADGFC. Lets try one, Bb, the notes are B C D E F G A B, Bb has 2 flats, B and E, so the scale is Bb C D Eb F G A Bb.
Now that you have had some practice writing out scales, we are going to explore another way to construct a scale using the Co5. Diagram 6 shows the Co5 with a line drawn to connect across the cricle. We are going to start with C major. Start with the note counter clockwise to the desired key. Then draw a line to the other side of the circle, in our case, F to B. Now label C as R for root, then skip a note and label it 2 skip another and name it 3, now go back to the note where the line started ( the one counter clockwise of the orginal key) and label it 4, skip one and label 5 ( we already knew this one ) skip another one and label it 6, finally skip one and label it 7. That may sound a little confusing, but take a look at the diagram. The pattern just skips the whole way through, 1 x 2 x 3...etc.
In the example below I have outlined the steps for A major and the proof using WWHWWWH. Find A on the Co5, then go one step counter clockwise ( D). Then draw a line from D to Ab. Mark A as R, then skip one and mark 2, skip one and mark 3. Then go back to the first note, D, and mark 4, skip one, mark 5, skip on, mark 6, skip one and mark 7. Now we can write out the scale, A B Db D E F# Ab. A is a sharp key, and you can't mix sharps and flats (just a technicality), so we will change the flats to sharps. Db is the same as C#, and Ab is G#. Rewrite the scale with the correct sharps, A B C# D E F# G# A. We can prove that this is correct by writing out A major using WWHWWWH; A B C# D E F# G# A. Since both scales match exactly, our method works.
Write out the Co5, then starting with Eb, write the circle again on the inside. The note inside the circle is the relative minor for the above key. Am-C, Em-G, C#m-E. We had to change the notes to match the respective key. For example, we changed Ab to G# because B is a sharp key. Work out the problems to prove the circle of relative minors is correct.
In the diagram you will see that I have boxed off the root and the notes to each side. I have done this to show you the relative majors and minors of the selected key. I also show the notes within the “Relative Box” 4 R 5 on top and 2 6 3 on bottom. There is not 7th in the relative box because in a chord progression, the 7th is usually neither a major or minor, but a diminished. Knowing this relationship makes constructing chord prgressions easier. If I know that 2 6 and 3 are the minors, I would not make a 4th chord a minor.
Another cool thing you can use the Co5 for is to construct the “scale tone 7th chord progression”. Normally this progression will start with the 4th and end on the Root but can start and end on any chord. Remember earlier we connected the lines within the circle? Draw that diagram. Lets take the 4th as our starting point, the next chord would be across the circle. Then come up counter clockwise to get the rest of the chords. For C major, the progression is F(4)-B(7)-E(3)-A(6)-D(2)-G(5)-C(R). Respectifly the chords types would be as follows, (maj7)-(dim or b5)-(m7)-(m7)-(m7)-(7)-(maj7). If we wanted to end on the B(7th) we would start with E and roll up to F, then cross the line ending at B.
Now its time for the combined Co5 diagram. With this you will be able to find the number of sharps or flats in a key, what those sharps or flats are. You can write any scale for any key within 5 seconds. You also know what the minor chord is for the key and the orientation of the 3rd for every chord ( whether the chord is major or minor using the “Relative Box” )
