Johann Georg Albrechtsberger is well-known as one of the principal teachers of Beethoven, but he had many other pupils, among them Hummel, Moscheles, and Mozart's son Franz Xaver. He published a treatise in 1790: "Gründliche Anweisung zur Composition mit deutlichen und ausführlichen Exempeln, zum Selbstunterrichte, erläutert"; this, despite its title, is mostly on counterpoint and fugue. It became parts 2-3 of a posthumous compilation (1826), in which part 1 is on harmony. That part is, however, a thorough-bass treatise; it makes little if any use of reduced categories of chords or Roman numeral labels. In the examples below, "chord of . . ." refers to the figure. Such labels approach the character of categories only when they have only one possible representative, as in chord of the eleventh and chord of the thirteenth below.
The progressions presented below are quite common in music about 1800. See Albrechtsberger's curiously convoluted explanation involving imagined tones. Also note that all the ninths in these examples would generally be considered "prepared" in modern textbooks, because there is a prepratory note in the preceding chord, a note that is reiterated (not held) in the ninth chord itself.
Another example of unprepared dissonances, this time involving the V9 in minor and major, and truly unprepared even in a modern sense:
Reference:
Johann Georg Albrechtsberger,
Gründliche Anweisung zur Composition mit deutlichen und ausführlichen Exempeln, zum Selbstunterrichte, erläutert (1790).
Johann Georg Albrechtsberger, ed. Ignaz von Seyfried,
Sämmtliche Schriften (1826). English translation as
Collected Writings on Thorough-Bass, Harmony and Composition for self-instruction (1855).
