Grackle is shipping now!

Grackle from Entropic Loop is an eurorack three-operator phase modulation synthesis voice, a synthesis method more commonly referred to as FM synthesis. While Grackle uses the fundamental techniques found in FM synthesizers such as the Yamaha DX-7, the implementation is unique; unlocking a new dimension in digital synthesis with sounds that stretch from the familiar to deep uncharted territory.

See the Manual for more detail on how Grackle works