Alegria Falseta on C
Here is a falseta for a traditional alegria in E major which breaks away from the standard major (E/A/B7) and minor (Em/Am/B7) chord progressions (hence a falseta on C, not in C) . After establishing the key in two compáses of typical alegria voicings, the falseta proper starts on a C natural played with only root, fifth, and octave (i.e. there is no minor or major tone). From here the falseta moves through passing chord changes to B7, repeats the C natural passage, then moves through another set of passing chords back to the traditional A/B7/E pattern.
For the most part this falseta is not overly technically demanding. If the a-i-i rasgueado on beats two and three of bar 9 (and following) is new to you, be sure to keep your fingers relaxed and aim for consistency. You can also play these 16th notes with an x-a-m-i-i-x-a-m-i rasgueado and come out with the same strong index down-stroke on beat one of bar 10 (which is the accented three-count of the alegria compás).
The Eb7 chord on beat two of bar 17 might likewise pose some challenges to those of you unfamiliar with this chord shape. Think of it like every other chord form you’ve ever learned: it can be tricky to make your fingers go in the right directions at first, but once you get used to grabbing the shape, it will be no problem to do quickly.
And once you have the rasgueados and chord shapes down: vary and embellish—especially with the repeated C natural phrase. I’ve written it without variation here for simplicity, but in my own playing when I come back around to the main idea of the falseta a second time (at bar 25), I often throw in some new rhythm or accenting. Repetition helps you get the most "mileage" out of a passage; the nuances of how you repeat keep things musically interesting.