Hot Cross Buns revised. A short example of reharmonization. I chose the simplest tune I could think of, with a slight variation, and incorporated some of the more common techniques of reharmonizing a melody that would be typically employed by jazz players. Download the PDF below and play along.
Rather than just a tonic chord through both measures I added the dominant on beat three with commonly used harmonic extensions to add motion and color. Any chord other than vii can be preceded by its dominant.
The same melody is now harmonized as if it were in the relative minor key of C# minor using the ii-V-i progression in the key of C# minor. This is a very useful technique and works in many cases if the existing melody can be considered part of the new harmony, either a triad member or in this case an extension which of course is even jazzier.
We begin with the IV chord (A) with extensions and move to A#dim7 on beat three creating a commonly used passing diminished seventh harmony between the IV chord and the tonic chord in second inversion (B in the bass). This progression is often used in a twelve-bar blues in bars 5-6 to connect the subdominant (IV) and the tonic (I). The diminished seventh chord in this context is known as a common-tone diminished seventh chord as it shares the note E with its chord of resolution. The critical voice-leading is A# to B in the bass and G to G# in the middle voice with the E as the common-tone, creating that nice chromatic movement we love.
The tonic chord reappears in second inversion on beats one and two followed by a secondary dominant C#7#9 or (V/ii) on beat three. When combined with bar seven we get the classic jazz turnaround progression. Secondary dominants are always desirable as they incorporate altered tones. This one is especially interesting since we have both the E-sharp and E-natural producing the 7#9 harmony.
As predicted the ii chord follows in measure seven but it is also altered to form a secondary dominant (V/V) leading to the dominant (V). I also included a commonly used chromatic passing figure (D#-D-C#-C) in the middle voice which you may recognize as part of many of A.C. Jobim's tunes. Typically this is shown on lead sheets as F#13-F#7#5-B9-B7b9 in which the chromatic passing tones are the thirteenth, sharp five, nine and flat nine respectively. Of course the ultimate goal of this chromaticism is the note B in the following tonic chord in measure eight which is there by implication only in this case to make things a little easier to play.
In summary we can formulate a few suggestions for your next project:
1) Try preceding any chord by its dominant (with the exception of vii) or the tritone sub for the dominant if the melody is accommodating.
2) Reharmonize the melody in the relative minor key if possible.
3) Make use of diminished seventh chords either as a secondary leading-tone function in which the diminished seventh chord resolves up a half-step into the next harmony, or as a common-tone diminished seventh chord in which the chord of resolution shares a common tone with the diminished seventh chord preceding it as in the example above.
4) Use secondary dominants where possible to add altered tones to the harmony. To review, a secondary dominant is a dominant seventh chord that resolves down by perfect fifth to roots of chords in the key other than the tonic chord (ii, iii, IV, V or vi). Chord vii, because it is diminished, has no secondary dominant. The tritone sub for any dominant is also very desirable.
It's a lot harder to play than it sounds. Some of the voicings are a bit unusual for guitar. You may also want to try playing just the changes as you sing the melody.
I hope you find something useful in this little exercise and thanks for reading and supporting!