| As you probably know, other than simple folk | | | | there is only two chords which have this |
| tunes, when you play more jazzy songs, or pop, | | | | hard-yearning quality: G7 and also the Bm7b5 |
| you usually don't use simple triads. | | | | chord (which is not used nearly as often, and we'll |
| Example: The common progression II-V-I in a folk | | | | ignore it here). |
| tune might be Dm - G - C. (Or in folk songs you | | | | But you have the freedom to step *out* of the |
| might use a IV-V-1, like F - G - C.) | | | | diatonic notes anytime you wish, and here's a |
| But in jazz, you'd normally play II-V-I in seventh | | | | way to step out all the time, and make your |
| chords, like Dm7, G7, CMaj7. (We'll leave pop and | | | | music drive forward all the faster ... |
| blues to the side for now.) | | | | Let us say that you are about to play a D-chord. |
| One of the interesting things about this little | | | | Any D-chord. |
| progression is how urgently that G7 chords | | | | Let us say you want to make that D-chord, |
| yearns to resolve to the C chord. The reason it | | | | when it arrives, seem really inevitable, and like |
| yearns so hard is that there are two notes in the | | | | we'd been really yearning for that D-chord. |
| C-major scale that are super-dissonant against | | | | Simple. Find the note a fifth above the D-note -- |
| the C-tonic note. | | | | that will be A, and play an A7. And then pretty |
| One is B, a half-step below C. | | | | much any D-chord following will sound like a |
| The other is Gb, a flatted-fifth above C. | | | | resolution from that A7. |
| The reason these two notes are so dissonant | | | | That A7 is called a 'Secondary Dominant.' It's a |
| against the C-note is that their harmonics do not | | | | dominant chord, by its form, though it's not the |
| align with the harmonics of the note C at all. | | | | true dominant chord that occurs naturally in the |
| The G-note, the normal 'Perfect' fifth, has | | | | diatonic key, so we call it 'Secondary.' |
| harmonics which align wonderfully with the C-note. | | | | Now given that the II-V-I happens over and over |
| And of course the C-note's harmonics align | | | | and over in jazz and other forms of music, and |
| wonderfully with the C-note: they're identical, for | | | | given that this and other progressions are usually |
| it's the same note. | | | | going down by fifths, you can *insert* these |
| But the B-note is just *off* the C-note, and the | | | | 'Secondary Dominants' to drive around the |
| flatted-fifth (Gb) is just *off* the G-note. And | | | | progression with more driving force. |
| because of this misalignment of harmonics, the B | | | | An Example: |
| and the Gb are very dissonant. | | | | The progression is VIm7 - IIm7 - V7 - IMaj7. In |
| When we play the G7 chord, a somewhat similar | | | | the key of C that would be Am7, Dm7, G7, and |
| thing happens. The F-note inside the G7 chord has | | | | CMaj7. |
| a similar, bad-harmonic-alignment with the B-note | | | | Now insert secondary dominants like this: |
| inside the G7 chord. Jarring. | | | | Am7 - A7 - Dm7 - D7 - G7 - Cmaj7 |
| And when we move to the CMaj7 chord, then | | | | You will hear that the A7 you insert makes the |
| the F-note resolves to the E-note a half-step | | | | resolution to the Dm7 'harder' and the D7 you |
| down (the third of the CMaj7) and the B-note | | | | insert makes the resolution to G7 'harder'. And of |
| resolves up to the C-note (the root of the | | | | course the G7 is already a dominant chord, so it |
| CMaj7), and this all sounds very happy. | | | | resolves very vigorously to Cmaj7. |
| How to Use this Knowledge | | | | Try it. You'll just drive all the faster down your |
| When playing strictly inside the diatonic key of C, | | | | musical highway! |