The dominant (Vchord)
The harmonic stronghold: The V7-I progression
The subdominant (IV) chord
The harmonic stronghold: The V7-I progression The strongest harmonic relation is between the V7 chord and the I chord, or the dominant and the root/tonic, if you prefer these terms. It is the V7-I relation that defines the root as the tonal centre. Just play the chords C-G7-C, and listen to how the G7 chord creates a tension that is resolved when you return to the C chord. You will hear that many, many songs end with the V7-I chord sequence, and it creates a firm and solid ending. If a line end on the V7 chord, you expect something to follow. It cannot be the last chord - at least in traditional harmony. If you play a 12 bar blues with a turnaround ending on the V7 chord, you have to play another verse. The V7 chord creates tension, and you have to resolve the tension. And the tension is not dissolved before you start the next verse with the I chord. Many songs have a structure where the first part end on the V7 chord, and you then expect some more to come. A song that almost any guitar player have played in the beginning of his or her career, is the ballad Tom Dooley. This song is usually played with only two chords, the I and the V7. The first part starts on I and ends on V7, and the second part starts on V7 and ends on I. xxxx Many other songs have the same kind of ending, but have more chords before the ending. There are not that many well known songs with only the chords I and V7, but the V7-I is a part of many other progression, so you will develop your knowledge and ability to identify the change in the following lessons. Compare the V-I change with the V7-I change. The V-I progression will also give some of the effects that the V7-I progression gives. But the V7-I progression gives a stronger statement. The two most important notes in a V7 chord is the 3 and the 7 (counted from the root of the chord, not the root of the key). If we look at a G7 chord, the notes 1-3-5-7 are G, B, D and F. In the key of C, the B is the leading note, a note that leads up to the tonic. The F is called the leaning note, a note that leads down to the third note, the E in C major. When you change from G7 to C, the B changes to C and the F to E, and then the tension in the chord is dissolved. If you play the G chord instead of a G7, you do not have the F, and then you cannot have the F to E movement. The interval between the B and the F is a diminished fifth, which sounds the same as the tritone (or augmented fourth, as it might also be called). This is a dissonant interval, and the dissonance is dissolved when it change to a major third (C and E). A simple major chord, such as the G, does not have this interval. The two notes will be notes 4 and 7 of the major scale: The 7 of a dominant 7 chord is the 4 of the tonic scale, and the 3 of the chord is the 7
of the scale. This might be very confusing, but if you review the lesson on harmonized scales, you will probably understand the relation between scale notes and chords built on these scale notes. Enough of that: The point is that the tritone interval between the 4 and the 7 of the scale, are the two most important notes in the dominant 7 chord. As long as you keep these two notes, the chord will function as a dominant 7, and it will lead you back to the tonic. By introducing new V7-I
changes in a progression, you will establish a new key and the song will modulate. But we will come back to this in another lesson. The dominant (V-chord)
The subdominant (IV) chord
