I started building DX-15 with a couple of goals in mind; to create something using our open source Complex Waveforms library and to follow the basic layout of the Yamaha CS-15 mono synth. The CS-15 is effectively two synths in one with dual VCO, VCF and VCA, a flexible routing system and multimode filters.
That said, DX-15 is not intended to be an emulation of the CS and sonically it inhabits a different universe. This is largely due to the sound sources, DX-15 uses a wide variety of FM, AM, wave folding and waveshaping multisamples recorded on analogue modular gear. The result is something much more unpredictable when compared with traditional, digital FM synthesis.