CTAG TBD open source eurorack synthesizer module

CTAG TBD as in "to be determined" is an open source eurorack synthesis module, allowing for easy implementation of own audio DSP algorithms.

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What it is:
- An open source Eurorack sound module based on the ESP32.
- With an easy to extend audio plugin architecture.
- What you make it.

CTAG TBD as in "to be determined" is an open source eurorack audio module.

It can be easily extended by your own DSP algorithms using a flexible c++ plugin architecture.
It's core feature is control of your plugin parameters through a web application UI and WiFi access. You basically log onto your TBD with a browser, choose your active plugin and modify its parameters. You can store patches per plugin. CTAG TBD recalls the last active plugins and patches upon reboot, so you continue making music where you left off.

All sources (hw+sw) are available on 

Why it is:

- A group of audio enthusiasts enjoying coding and hardware making.
- Build a platform to learn, build and practise skills, and engage students.
- To allow anyone to understand technology by offering open access.
- To squeeze and optimize code so that it can work on a small embedded system.
- To fight boredom and despair of Corona Virus!


- Easy DSP plugin development.
- With web UI user interface by wireless browser access.
- Through a REST-API.

Potential new features / current limitations / work to be done:

- FAUST support.
- Bug identification and fixing.
- Code refactoring to make things more beautiful.
- More user friendly interaction.
- Documentation / tutorials.
- Your ideas?

How to engage yourself:

- Join the enthusiastic developer team on Github.
- Help build and spread the hardware module (and the word).

More ideas?

If you are interested in beta hardware email subject "TBD REQUEST".

  • 1 × ESP32
  • 1 × WM8731 Audio ICs / Audio CODECs
  • 1 × wm8978 Audio ICs / Audio CODECs
  • 1 × R-783.3-1.0 Electronic Components / Misc. Electronic Components

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Elliot Williams wrote 04/15/2020 at 07:53 point

Very cool!  Adding WiFi to this kind of minimal DSP/software module is brilliant.  B/c what's missing in (e.g.) the Expert Sleepers is a nice UI.  Doing that in the browser is sweet.

An extra layer could be a meta-configurator, where you can set up (however many) of the units at once, store the parameters/functions/behaviors on the computer, and then recall the module funtions wirelessly as if it were a patch.  (Minus the cables, of course.)

Intranet of Modules.

  Are you sure? yes | no

Robert Manzke wrote 04/30/2020 at 05:03 point

Hi Elliot, a meta-configurator is a great idea! It should be straight-forward to implement given the well defined REST-API. Thanks for your interest :)

  Are you sure? yes | no

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