Chromatic hexachord

In music theory, the chromatic hexachord is the hexachord consisting of a consecutive six-note segment of the chromatic scale. It is the first hexachord as ordered by Forte number and its complement is the chromatic hexachord at the tritone. For example, the two hexachords below are complementary chromatic hexachords.

This is the first of the six hexachords identified by Milton Babbitt as all-combinatorial source sets, a "source set" being "a set considered only in terms of the content of its hexachords, and whose combinatorial characteristics are independent of the ordering imposed on this content" (Babbitt 1955, 57). In the larger context of thirty-five source hexachords catalogued by Donald Martino, it is designated "Type A" (Martino 1961, 229–30). Applying the circle of fifths transformation to the chromatic hexachord produces the diatonic hexachord (Babbitt 1987, 93). As with the diatonic scale, the chromatic hexachord is, "hierarchical in interval makeup," and may also be produced by, or contains, 3-1, 3-2, 3-3, 3-6, and 3-7 (Friedmann 1990, 111).