Full additive voice

Plus Legio is a complete additive synth voice with simple envelope control and a complex internal modulation matrix. Timbre controls the levels of the additive oscillators, which can also be modulated by the internal ADSR envelope by way of the Mod switch. An optional chorus LFO brings width and movement to a sound, which can, in turn, be modulated by the ADSR envelope for extra complex and evolving notes. Add in stereo phase-modulation inputs and you've got a wildly complex synth voice that's easy to control, all in 6 HP!

https://noiseengineering.us/products/plus-legio/