The Secondary Dominant Chord

Alright guys', learning about the secondary dominant chord is the last issue we're going to cover before I show you wonderful examples of many of the chord progressions we've been learning in songs we're all familiar with.

Let's rewind for a moment. When we started talking about the world of harmony we discussed three main functions that create the movement within each and every chord progression.

The first degree we covered was the tonic; the point of full rest, stated by the roman letter I (C major triad chord in C major scale.)

If each harmony progression achieves a full rest then there has to be a point which created the most tension toward the tonic. We name the function the dominant and we state it as the fifth scale degree (V in roman letters).

The fifth degree had become the most natural dominant chord (The seventh degree is functions also as a dominant) since it is a stable chord, meaning that the distance between its root note and its fifth note is a pure quint unlike the seventh degree which has a tritone (diminished fifth) between the first and the fifth note which is highly unstable.

The third note of the fifth degree (If we take C major for example Then G (G, B, D) would be the dominant chord) is the leading tone (seventh note) of the scale (B is the leading tone in C major scale) which is the note that wants to go back to the C note in the most obvious way.

We have added the seventh note of the dominant chord in order to increase even more the tension toward the C chord for F the fourth note in C major is an outside note pointing clearly toward E the third note of C major (So we created a G7 chord as the dominant seven of C major scale by adding the F note to the G triad chord).

Click here to cover this issue in details in this page called "Three chords and the truth."

Today I'd like to talk about the dominant chords of the other scale degrees.
When we've learned about the diatonic circle chord progression we realized that the chords within a major or a natural minor scale move naturally in circles of fifths.

But we know already that the dominant chord is functioning as a dominant only when a major chord is being pressed; so what do we do when the fifth of a chord is a minor chord?

The most example of this issue is the fifth of the tonic of a natural minor scale.
Originally the fifth of a minor scale is a minor chord (Em is the original dominant of Am) so what do we do?

Simple, we raise the third note of the chord and we change the chord from a minor to a major seven chord (looking at it scale wise we actually raise the leading tone of Am by creating an A harmonic scale; that's why it is meant for).

But let's look at it from a harmonic point of view? Where did this chord derive from? And the answer is easy. We simply borrowed this chord from its major twin thus E7 the dominant of Am is taken from A major scale.

Now let's try the dominant chords of the other scale degrees by borrowing their second dominant chords from the major twin. Let's take the second degree of Am (Dm). If we look for its upper fifth (For we always fall in fifths) we get the A minor chord.

This chord however cannot function as a dominant since it is not a major chord.
Let's raise the third note then and turn A minor to A major.
If we ad the seventh note of the chord to A minor we get the final chord A7, the secondary dominant of Dm (which is the second degree of C major scale).

A7 is the true fifth of D and this is where it is borrowed from.

To make a long story short I add here an image of all the secondary dominant of each and every scale degree in C major. I suggest you play this example until you know it by heart. It will bring you BIG returns in the future.

When you'll look above the secondary dominant of each chord (in the second half of the bar) you'll see two signs and a slash. The upper sign stated that this chord is a dominant of the lower sign. V/IV would be the dominant of the fourth degree.

And here's a free piano chord chart of all major and minor scales.
The sequences are written in the major scale and if you'd like to play them in the minor scale all you have to do is start from the sixth degree.

I'm proud to tell you we're now far enough to try out and play many great pop songs. I'm sure you're going to like playing all these songs with the extra pleasure of understanding what you're really performing. Let's go! (coming soon)