Abstract: Apparatus is provided for use in electronically creating music or special sound effects through the generation and modification of audio frequency, electrical, tone sequence signals. The apparatus is characterized by its ability to generate random, as well as cyclically patterned, tone sequences; by the degree of control provided over both basic parameters of generation and a number of available special modifying effects; and by the reliability of the apparatus and the relative economy with which it may be maufactured. The preferred form of apparatus employs functional stages or modules largely implemented with solid state components. Among the novel functional modules utilized in the apparatus is an improved type of low pass, electronic R-C ladder filter employing diodes and fixed value capacitances, rather than transistors or/and variable value capacitances.