The K5 chip is an additive synthesizer that builds its sound by adding 5 sinewaves.
No filter required, yes, additive shaping.
The chip can run in 2 modes:
Mode1: 5 CV inputs selects the level of fundamental, 2nd, 3rd, 4th and 5th harmonic levels and a 6th CV is the pitch CV for the fundamental frequency, 1volt/octave. This mode is for modular synth usage and monophonic.
Mode2: 5 CV inputs shapes the envelopes of the fundamental, 2nd, 3rd, 4th and 5th harmonic level. the 6th CV can be used for pitch modulation and it is 8 note paraphonic with MIDI input. Envelopes use the single knob Roland way.
This is a very cool chip that can shape the sound without filters.