DIRECT MODULATIONS
Direct modulation is modulation that does not contain common chords.
Figure: Direct modulation
The next figure shows an example of direct modulation at the beginning of Chopin’s Prelude No. 17 in Ab major. We see the modulation from the Ab major key to the E major key.
The diatonic tones of the Ab major key and the E major key are also shown in the figure. We see that they differ in all the note names. Thus, to find the exit point, we must search for the last occurrence of any diatonic tone of the Ab major key. To find the entry point, we must search for the first occurrence of any diatonic tone of the E major key. The notes corresponding to the entry and exit point are marked in blue in measures 18 and 19 in the figure.
The Ab major triad chord which occurs at the exit point is neither a diatonic chord nor a common type of altered chord in the E major key. The E dominant seventh chord which occurs at the entry point is neither a diatonic chord nor a common type of altered chord in the Ab major key. Thus, we can conclude that there are no common chords and this is a direct modulation.
Also, this is an example of common tone modulation. The Ab major triad chord has a single pitch common with the E dominant seventh chord: Ab (or differently spelled G#) in the melody.
Also this is an example of the chromatic mediant modulation. Chromatic mediants were explained in chapter Chromatic mediants. If we take the definition of chromatic mediants literally then the modulation should be from the Ab major key to the Fb major key (or from the G# major key to the E major key) so that the tonics are a third apart. However, since musicians normally do not use the Fb major key or G# major key, their enharmonically equivalent keys are used in the score.
