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 .