If you look at the set of Eurorack modules offered by vendors like Mutable Instruments, you quickly realize that they break down into multiple discrete categories:
- Sound sources
- Modulation sources
- Sound modifiers
- Sequencing, control and meta
Initially, the ISHIZENO i8, was conceived in a similar fashion, but after having learned a few lessons, I am starting to believe that we should depart from this model, and design our submodules as full-blown synthesizers that combine generation, modulation, and modification, while leaving the sequencing and plumbing functions to the embedded Raspberry Pi and our crosspoint switches. Doing so, a single i8 module could give you 8 individual monophonic synthesizers, instead of just 2 or 3 if you were to use 3 sub-modules for every voice (source, modulation, modification).
With such an approach, each synthesizer submodule could have its own personality. For example, one could be as simple as the Werkstatt-01 Moogfest, while another could be as advanced as the Mutable Elements. They would all share a common mechanical and electrical interface, while having customized graphical interfaces.
To take it further, we could borrow an idea from another synthesizer manufacturer: Tiptop Audio, and its intriguing Z-DSP cartridges. This would allow modules to be extended from the outside, instead of having to take them out of their racks. Such cartridges could be used for delays, filters, or reverbs. Each channels could include one or two Z-DSP ports, making the platform even more extensible.
With that in mind, we need to remember the advice we were given by our informal advisor: “build 3 or 4 brilliant submodules.” Now, these submodules have to be full-blown synthesizers. It’s a lot more work, but it’s a lot more interesting as well.