We call Crave, Model D, CAT WASP, Pro1 and all the others „semimodular“ synthesisers. They are fully fledged standalone Synthesizers. But they also integrate themselves into the big modular world of Eurorack. A couple of patch cables and a single module and you’re in!
It's very easy to upgrade and enhance the sounds and capabilities: give your Crave a second oscillator, change the filter on the Model D or enhance the Neutron with a sequencer. We start small in this video by adding only a single module.
You can find all synthesisers and modules on
http://www.behringer.com