Modulation is the core concept of modular synthesis: parameters changing over time, adding movement and musical interest to what would otherwise be merely static sounds. Being able to control the amplitude of signals throughout a patch is therefore essential, and one can never have too many voltage controlled amplifiers (VCAs). Designed as a fully-featured modulation hub for Eurorack synthesisers, Morph 4 takes the basic concept of the multi-VCA module to the next level.