This invention provides a signal processing and signal synthesis technique from a family of signal processing and signal synthesis techniques designed to readily interwork or be used individually in creating new forms of rich musical timbres. A real-time controllable mix of a plurality of multiple output frequency-reduced signals and the cross-products of these signals provides rich animated harmonically partitioned spectra. Mixing parameters may be recalled from stored program control or modulated in real-time by arbitrary control signals, including envelope generators, low-frequency oscillators, and those derived from an original input signal, and specifically including the amplitude of an original input signal. The real-time controllable mix may have multiple outputs and be subjected to further signal processing and multiple-channel amplification. The invention may be used individually or in conjunction with other signal processing and signal synthesis techniques in creating new forms of rich musical timbres.