IMDI

IMDI is the “Inter Module Digital Interface”. Besides the classic modular control methods, CV and Gate, IMDI is a third way to send control data within a modular synth via regular patch cables, with the advantage that, as it is a digital communi­cations protocol, more complex information can be sent over one cable.

It is no coincidence that IMDI sounds similar to MIDI! It is based on the established and well-known MIDI serial protocol, using the complete set of MIDI messages, enhanced by a set of conventions that are created specifically with the application in a modular synth in mind – for example, receivers typically operate in OMNI mode, with channel selection made by hardware patching. In practical use, this means that you can patch MIDI signals using the exact same cables used for existing CV and Gate signals.

By leveraging the MIDI protocol, this opens up possibilities such as:
* Versatile DAW integration (bi-directional, including MIDI clock sync)
* Easy integration of external MIDI-Controllers without the need of additional MIDI-CV/Gate Interfaces
* Easy polyphony for modular synthesiser patches
* Complex control without a lot of patch cables
* Seamless interaction of CV, Gate and MIDI/IMDI

… and much more

Initially created in 2023 by John Tuffen of wonkystuff (a UK-based 3rd party manufacturer of modules for the AE modular system), we adopted it for our modules and it is an integral part of any new module whenever it is sensible to do so (it is also being retro-fitted to new revisions of existing modules). The idea is of course not limited to AE Modular; using the standard MIDI protocol messages allows easy interaction with Eurorack for example.

As is quite common in the “modular world”, the actual innovations often happen at the module-level: tight integration of MIDI is meant to pave the road for new options that are very hard to implement with CV/Gate only. For example MIDI-based sequencers or effect-generators; live-coding; integration of BLE-MIDI or USB-MIDI; recall of settings and many other features that module-developers may imagine!

For us, the innovative aspect is to extend the available patchable signal types to include MIDI directly, not simply converting to CV/Gate immediately. The ability for a single cable to carry many control signals simplifies patches enormously (for example ‘MIDI controlled oscillators’ can have dozens of parameters without being burdened by a huge front panel; external MIDI controllers can be used instead). The immediate, visible (tangible?), physical MIDI channel selection is an important aspect; minimising the need to menu-dive, and simply to patch with a flow…

For us, the most inspiring use is the possibility of EASY POLYPHONY in the modular world, without having to deal with a multitude of patch cables for CV, Gate, Modulation etc. — a single cable can carry all of this information! The ability to use traditional DAWs for note *and control* sequencing is also a huge plus — upcoming modules are also able to convert CV to MIDI CCs, allowing performances to be recorded and replayed at a control level also.