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Simplified Music Chord Theory
Scale in key of C
Understanding chords really begins with understanding a scale. Let us use the key of C for our scale since that will yield simplest results. A scale is generally taken as 8 notes, which is also considered one “octave”. The scale begins on a note and ends when it reaches that same type of note. Let us look at a simple C scale looking at it three different ways:
Scale, Key of C to a Singer
Do, re, mi, fa, so, la, ti, do! (note that it has 8 notes, and begins and ends on “do”)
Scale, Key of C by name
C, D, E, F, G, A, B, C (8 notes again, and begins and ends on C)
Scale, Key of C by number
1, 2, 3, 4, 5, 6, 7, 8 (8 notes again, but this time we called the 8th note 8)
The above three representations are all really the same. How do we use this for chords? Well let us start with a simple major chord. A major chord is always made up of the first, 3rd, and 5th notes of its scale. So C Major is simply C, E, and G. Not so hard, eh?
What would a sixth be? Can you guess? Well we begin with a major chord, and then add the sixth note. So a major sixth (normal sixth) would be: C, E, G, A.
Now the C scale above is not all of the possible notes. It is merely the 8 notes making up the C scale. If we think in terms of a piano, the C scale is all of the white keys. It does not use any of the shorter black keys, which are sharps and flats. When we look at all of the possible notes, we call that a chromatic scale. All of the possible notes in a chromatic scale, not counting any repeats, not even one, are 12 total. They are:
C, C#, D, D#, E, F, F#, G, G#, A, A#, B, (and then C would repeat next)
Of course, that shows the chromatic scale using all sharps. A sharp sign # means to raise a tone one half step. So C# is one half step higher than C. For every sharp representation, there is also a flat representation possible. Instead of raising C one half step to get C#, we could have also lowered D one half step to get a Db. The “b” sign is for “flat” just as the “#” sign is for sharp. C# is the same note as Db. There are just two ways of showing it. Sometimes it s more convenient to show it as a sharp, and sometimes as a flat.
Minor chords, Dominant 7ths
It was necessary to talk about chromatic scales before talking about some chords, such as minors and dominant 7ths, since they go off of the normal C scale and involve half steps. We had said that a major chord was made up of the first, third and fifth notes of the scale, C, E and G. A minor is close, but it “flats” the third. So a C minor chord would be: C, Eb, G. Note that we could have shown this also as: C, D#,G since D# and Eb again are the same note.
When we talk about 7th chords, one would think that we take a major chord such as C,E, and G, and add the seventh note of the scale, which would be “B”. That in fact is exactly what we do for a C major 7th chord. However, when we just write 7th, it is taken to mean a “dominant 7th” which flats the 7th note. So, C 7th is: C, E, G, and Bb. This again can also be written as C, E, G, A#.
So, the above covers the 7th chord. The C major 7th chord would in fact be what you would have guessed: C, E, G, B - where B is clearly the 7th note of the scale.
Now, how about a minor 7th chord? Let us begin with the minor, which flats the third, and then add the 7th. So, let us begin with C minor which is C, Eb, G and we will add the 7th which again is Bb and we get: C, Eb, G, Bb. Recall that when we just say “7th” it refers to the dominant 7th, which is a flatted 7th of the scale. There is a version of a minor chord that uses the major 7th, it is called mmaj7th. It is a somewhat confusing name, being a minor, major7th. I would agree that minor-major in the same sentence seems like a contradiction of terms, but they refer to two different parts of the chord. The minor refers to the first three notes, C Eb, G. The major 7th means that we do not flat the 7th note of the scale. So, therefore a C mmaj7th would be: C, Eb, G, B.
Well, if you follow all of that, many of the rest of the chords should make sense. An augmented chord is also called a + chord, or a +5 chord. You can probably guess what that chord does. It raises the fifth note of the scale one half step. So a C major chord again is C, E, and G, which are the first, third and fifth notes of the scale. So, a +5 would cause the chord to become C, E, G#.
On the other hand there is a -5 chord. So, a C-5 would be C, E, Gb or C, E, F#.
One strange “chord” is simply called a “5”. It really is only two notes, the first and the the fifth of the scale. So, a C5 is merely C and G. Note that this chord is also sometimes called C major no 3rd. Can you see that? If C major is C, E, G, then C major with no 3rd is simply C and G.
9ths, 11ths and 13ths are somewhat understandable, but they do add some confusion. The understandable part is that they do in fact add the note that one would think. They also add a few more however. But let us start with the reasonable part. A C 9th would add a “D” as one might expect - the ninth note in the scale. A C 11th does add an “F”, the 11th note in the scale, and a C 13th does add an “A” which is the 13th note in the scale. However, C9th also adds a dominant 7th and therefore is: C, E, G, Bb, D. The 11th adds not only the dominant 7th but also the 9th and therefore is: C, E, G, Bb, D, F. The 13th is similar to the 11th and becomes: C, E, G, Bb, D, A.
The minor versions of 9th, 11th and 13th? They really follow the same formula but begin with the minor rather than the major chord. So C minor 9th is: C, Eb, G, Bb, D.
Scales / Chords other than C
If the above makes sense to you, you are getting close to understanding the basic make up of chords. Some is simple mathematics, and some is convention, established years ago. Of course you could say that all this is in the scale and key of C. Other keys are harder. Well, yes and no. The other keys may have odder looking sequencing, but they follow all of the same rules. This is where the mathematics come in. To look at a D scale, for example, note that a D is two half steps in the chromatic scale higher than C. Use that then to calculate all of the notes of the D scale. Doing that a D scale is:
D, E, F#, G, A, B, C#, D
A D major chord is still the first, third and fifth of the scale, and is: D, F#, A.
D minor is similar with the third “flatted” and would be: D, F, A.
D 7th would be D, F#, A, C since flatting C#, the 7th note in the D scale is really just C.
D major 7th would be D, F#, A, C# (the 1st, 3rd, 5th and 7th notes of the scale)
If you understand the above, you may in fact be able to even figure out some of the unique chords that guitar players continue to come up with. I just noted a new one in one of my song books. It was a D major add 2. What? we might say? But then we would get a grip on ourselves. We would put together the D major chord of D, F# and A, and then merely add the 2nd note of the scale, an E. Then we would get D, E, F#, A. Voila ! See? not so bad.
If you are like me and appreciate the mathematics, but then have a hard time memorizing 28 chords versus 12 notes of the chromatic scale, 336 possibilities. And even less likely to memorize the guitar fingerings for those 336 down 12 frets making 4032 possibilities, then you might need a simple aid. The software program being marketed by rpsoft 2000, called musicord, is reasonably priced and serves as a simple reference for most of those common chords,