Tone clock

While the emphasis of tone-clock theory is on creating the chromatic aggregate, it is not a serial technique, as the ordering of pitch-classes is not important.

However, it bears a certain similarity to the technique of serial derivation, which was used by Anton Webern and Milton Babbitt amongst others, in which a row is constructed from only one or two set-classes.

In her monograph Chromatic Maps, New Zealand composer Jenny McLeod extended and expanded Schat's focus on trichords to encompass all 223 set-classes, thus becoming a true tone-clock theory.

[3] She also introduced new terminology in order to "simplify" the labelling and categorization of the set-classes, and to draw attention to the specific transpositional properties within a field.

The tone-clock creates vast possibilities of intervals, yet are confined into a single clock of usable triads.

Peter Schat's Zodiac of the Hours , which graphically represents the tone-clock steerings of the twelve hours. X can only be steered as a diminished seventh tetrachord (hence, the only non-triangular shape). Each point of a shape represents a pitch-class on the chromatic circle, and each shape represents one transposition or inversion of an hour.