Abstract: This invention relates to a key system for electronic musical instruments, comprising a key circuit for forming control signals and control circuits for transmitting sound signals in response to the control signals. The key circuit produces the control signals in dependence on the position of a key and/or on elapsed time after depression of the key. Coupling means forming part of each control circuit modifies transient characteristics of the control signals whereby each control circuit can transmit notes in such a way that they each have a different build-up time. This enables the instrument to make a sound similar to that produced by a conventional non-electronic instrument.

Abstract: A method of and apparatus for increasing the fullness of tone of electronic musical instruments having at least one set of tone generators corresponding to the tonal range of the instrument through the playing of individual registers and/or groups of registers optionally selectible from these tone generators, by one or more key systems. Electric sound oscillations which are provided by the tone generators and optionally combined to form registers are subjected to cyclic phase shifts, the period of the cycle of which is so low that these shifts are not acoustically discernible in the individual sound or register or group of registers.