We will now go back to our previous effort to write a pattern prelude and try to incorporate some of the modulatory voice leading patterns.
We will also follow the advice of C. P. E. Bach (one of J. S. Bach’s sons and an extraordinary composer in his own right) on how to improvise a prelude:
an improvisor extemporizing a prelude “fashions the bass out of the ascending and descending scale of the prescribed key, with a variety of figured bass signatures, and may . . . perform the resultant progressions in arpeggiated or sustained style . . . A tonic organ point is convenient for establishing the tonality at the beginning and end. The dominant organ point can also be introduced effectively before the close.” 1
Our goal will be to fill in the path from the opening structural tonic or dominant using a descending scale.
C.P.E. Bach refers to the bass line as a “bass theme” and suggests adding a structural upper voice he calls the “singing upper part.” This singing upper part, is none other than our descending parallel tenths exercise.
We can also lead to the structural dominant with a lower neighbor to create a more satisfactory cadence:
For the opening pedal point we will use our opening formula:
For the dominant pedal we will use a double cadence:
So the outline of the prelude will be as follows:
So far, this is not much more developed than our first prelude. However, now we can use the 3-2 sequence. We can then add either 6/4/2 chords to resolve them locally to other keys.
Notice that the 6 chord on B has to be voiced differently if we want to avoid doubling the leading tone. Also notice that now we have seven chords. Since harpsichord and organ don’t have dynamics, Baroque keyboard composers often favored symmetrical number of bars to clarify cadential structures.
We can add a 6 chord on C after the first chord to create a chain of 6-4/2 progressions:
The next portion of the scale can be expanded similarly:
And in four parts:
Notice that now the motion from C-G and from G-C are symmetrical in duration and construction (almost like a rhyming scheme).
We can move on to the final cadence through the soft hexachord since we added an F leading to our final dominant pedal: