Another good way of thickening the melodic line, or to create a harmonic melody, is to use block chords. These are usually played in rhythmic unison with the melody, or very close to it. The name of this harmonic device comes from the fact that the chords are actually blocked within an octave that outlines the melody and, as consequence, the harmonic direction.
The chord constitution for the block chord motion can be based on different chord types – tertian or quartal chords (typical of pentatonic voicings – more ambiguous); and probably the “rule” that one should be aware of is to avoid harsh dissonance near the top voice of the block chord – which is basically a melody note:
The same harmonic melody using block chords with secondary dominants and chromatic approach chords:
Eventually, block chord voicings can be used to make parallel chord sequences, either real or tonal:
Example beginning with tonal parallel and ending on real parallel block chord motion
Here is another example using a real parallel chord sequence applied to a block chord movement in (mostly) minor third cycles using an added ninth chord:
Although drop 2 voicings are not technically block chords, these are commonly used chords in this type of harmonic approach since this chord voicing creates a somewhat more sophisticated sound than the blocked chords approach:
Using the secondary dominants example with drop 2 chord voicing
Finally, another way of using block chord motion as a tool for step-wise harmonic movements is to use the scale harmonization from the 6th diminished scale, where you have a continuous cycle of tension and release caused by the alternating tonic and dominant chord harmonies as you go up or down the scale:
