Thank for your advice!
Maybe I will start with those Doepfer modules. After adding a filter,vca, attenuverter, would it be a usable synth voice?
I would like to learn about the signal flow, and then the modulation, effects,... Where could I read more about it? Is there any threads that will help with basic knowledge?-- baygiooday
You might want to research "Eurorack Synth Voices". A synth voice is generally a complete compliment of VCOs, filters, VCAs, LFO, etc. Most if not all elements are normalized (internally patched) with the ability to break those normal connections and reroute them for advanced patching.
The Behringer Neutron can be considered a synth voice and at $300US is a pretty good set-up for learning on. The Intellijel Atlantis is a great synth voice. But it's more expensive and requires a case to power it.
As far as learning. There are tons of great tutorials on Youtube that take you through the very basics of modular design and use.