The Cadence is the essential chord movement that establishes the feeling of the Key.
The Bass outlines the harmonic movement up a 5th (Dominant) or down a 5th (Sub-Dominant).
The Leading Tone (here: B) in the V chord creates melodic and harmonic tension and raised energy.
The Tonic note (here: C) is shared between I & IV, so there is less tonal movement and energy. It “cools down,” where the Dominant “heats up.”
These are combined to create the Grand Cadence:
This IV-V-I progression is closely related to the ii-V-I progression:
Only one note is actually different from the IV-V-I: C becomes D. This is why IV and ii have similar properties and movements, because they are so closely related.
Notice the Bass movement by 5ths.
We can continue this movement to create “Circle of 5ths” Progressions.
See how every movement counter-clockwise is a V-I progression?
G-C = V-I
F#-B = V-I
Eb-Ab = V-I
If we move by 3 tones we get a ii-V-I.
D-G-C = ii-V-I
C-F-Bb = ii-V-I
5 tones, iii-vi-ii-V-I.
7 tones, IV-vii°-iii-vi-ii-V-I.
This is every chord in the Key.
Key of C: F, B°, Em, Am, Dm, G, C.
Key of Bb: Eb, A°, Dm, Gm, Cm, F, Bb.
Key of B: E, A#°, D#m, G#m, C#m, F#, B.
This becomes a little tricky with progressions larger than 5 tones, because we have to remember the notes that are sharp and flat for the Key that we’re in. It’s easier to see on the Keyboard than the Circle.
The Circle of Fifths allows us to unlock progressions that seem complex, but are actually just movements by Fifths, and to play them in every key!
The Dominant 7
The V7-I Cadence is the most basic element of the harmonic vocabulary and is so common to all music that we should memorize it in every position, in every Key.
Continue this in every Key, Major and Minor.
The Dominant 7 chord has a very powerful function, because of the symmetrical Tritone contained in its’ structure (between intervals 3 & 7). This allows us to use tones that are “outside of the key.”
Look back at our ii-V-I progression, and see how the fundamental bass moves down by a 5th. Here, the ii chord is a fifth above the V, a Dominant relationship. Essentially, the ii-V-I is the same as two V-I progressions moving down.
So we can use the Dominant 7 chord in place of the minor ii chord.
The V7/V is the Secondary Dominant. It means that this chord is the V of the V.
Ok so big deal, right? All we’ve done is altered the minor triad that’s diatonic to the key, into a Dom7. But this principle is at the heart of some of the most interesting harmonic movements in the music of great composers like Mozart and Beethoven. In fact, if you’re having trouble figuring out what a chord is in a piece of music, because it doesn’t seem to fit into the key, it is very likely to be a Secondary Dominant of some kind. Not always, but often enough!
This has further reaching effects however. Let’s consider the IV-vii°-iii-vi-ii-V-I in the key of C. The vii° chord is B°. The diatonic fifth above B is the IV chord, F. However if we use the Dominant 7 at the perfect fifth above B, we get F#7.
Our new progression is (V7/vii°)-vii°-iii-vi-ii-V-I. The F#7 chord has the notes: F#, A#, C#, E; three sharp tones and harmonically we’re still in the key of C! Wow.
We can continue this even further and connect pretty much any chord to any other chord, without “modulating” or moving the music into a new Key, because of harmonic relationships that eventually can be traced back to our original Tonic chord: C Major.
Choose a tone at random from the Circle of Fifths. This is your I chord. What are the IV & V chords in the Key you’ve chosen? Do this for many different tones on the Circle.
Now find ii-V-I progressions in every Key. Find iii-vi-ii-V-I progressions in every Key.
Notice how the same chords have a different meaning in each key. For example, G is a V chord in the key of C, but G is the ii chord in the key of F.
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