The Rule of 7th's

There's 3 kinds of 7th chords: Major, Dominant and fully Diminished.
An easy way to find these chords is to think about it from the view of the
chord tones. To better understand chord tones let's have a quick review of
how to find them.

Here's 3 ways to define the notes in a scale...
By Key - C.D.E.F.G.A.B.C: or
By Solfege - Do. Re. Me. Fa. Sol. La. Ti. Do: or
By Degree - 1.2.3.4.5.6.7.8
By interval - 2 whole steps, 1/2 step, 3 whole steps. 1/2 step = 2,1/2,3,1/2

All the above describes a Major scale and in this case we've placed that in
the key of C. So now to make a chord, take every other note out of the
scale...
Triad = C.E.G.          The 7th chord = C.E.G.B
        Do. Me. Sol.                    Do. Me. Sol. Ti.
        1.3.5.                          1.3.5.7
        2 whole steps, 1,1/2          2 whole steps, 1,1/2, 2 whole steps

A chord tone is every other note taken from the scale of the particular
chord your looking for. Major chords come from Major scales. Minor chords
from minor scales and so forth...

Now back to 7th chords. Here's a simple rule that's easy to follow:
7-8 = 1/2 step = Major 7th (Cmaj7).
If the interval from 7 to 8 or Ti to Do or B to C is a 1/2 step then the
chord is a Major 7th. Think about the interval between 7 and 8 in a Major
scale, that's a 1/2 step too.

7-8 = 1 full step = Dominant 7th (C7) if the interval from 7 to 8 is a full
step the we call that a dominant 7th. That name really comes from the
function of the 7th chord and how the chord "moves" in a progression. More
about that later.

7-8 = 1,1/2 steps = Fully Diminished 7th (CDim7) If the interval from 7 to 8
is a step and 1/2 then the chord is a fully diminished chord. As you may
know, diminished chords are special in their interval relationship. Every
chord tone in the chord is separated by the same interval, a step and a 1/2.
And it's the only chord that turns around on itself.

If you have questions about the above, give us a call or stop by the store.
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magic!