Fritz Heinrich Klein

[2] Klein's twelve-tone theories, which he refers to as "extonal", appear to originate independently of Schoenberg's as with Josef Matthias Hauer's, and these claims as well as frequent stylistic changes helped to exclude him from the Second Viennese School, though Klein's theories where highly influential on Alban Berg.

Klein considered his piece for two pianos, Die Maschine: Eine extonale Selbstsatire [The Machine: An Extonal Satire[3]], Op.

1, and derived it from the pyramid chord: difference by transposing the underlined notes (0369) down two semitones.

For example, since the sum of numbers 1 through 11 equals 66, an all-interval row must contain a tritone between its first and last notes (as does the Pyramid chord).

4, appear on Steffen Schleiermacher's album The Viennese School - Teachers and Followers: Alban Berg (MDG 613 1475-2), along with music by Theodor W. Adorno and Hans Erich Apostel.