Calling all audio and hardware hackers!

I am part of c3lingo, a community of interpreters offering simultaneous translations at cultural and social events such as Chaos Communications Congress and Camp, Fusion Festival, TIN-Solifest and others.

The project has been running for many years, but especially since we are increasingly active outside of C3, we have some hardware challenges as there is often no pre-existing infrastructure and/or little budget for hardware.

That’s why we want to build our own interpreting consoles that are as open and free as possible, inexpensive to buy, and customized to our use-case.

I am looking for more information and support with knowledge, tips, and also active help with planning and construction. More details below.

Consoles on the market are expensive and usually part of a (conference or interpreting) system, the target group are conference centers and large events, accordingly a console costs four to five digits and also needs additional hardware for signal distribution and processing. Renting is cheaper, but still too often prohibitively expensive for small, often self-organized events.

What features should those consoles offer?

  • Feed in stage audio and output on 2+ headphones / headsets so that the interpreters can hear the speaker(s); the input should be digital or balanced (XLR)
  • Record interpreted audio from the 2+ headsets or microphones (connected via XLR, RCA jack, or combination) and send them to the outside (usually to a mixer, FOH, etc. – but “outside our responsibility”); either pre-mixed or individual signals per microphone, or digitally
  • The headphone volume should be adjustable separately
  • Optionally, you should be able to mix your own microphone signal or that of the co-interpreters in your own headphones for monitoring; the relationships between the stage signal, your own microphone and other microphones should then also be adjustable
  • Each microphone should be switchable (on / off) without emitting interference signals
  • Each microphone (or the entire output) should have a cough button to briefly duck the signal (while the button is held)
  • LEDs or light-up buttons should indicate which microphones are “on air”
  • Optionally, an externally controllable signal LED would be nice, which indicates whether the signal “upstream” is still “on air”, i.e. whether it is still played to listeners or is already cut
  • Optionally, a simple return channel to signal the upstream technology if there are any problems or questions, e.g. “We don’t hear anything, please check input”, “technical problem, please come over”, and such.
  • Everything should be shielded against EM such as cellular, DECT and Wifi, to prevent interference in the signal
  • Latency is not critical, but should be as low as “affordably” possible.

Bonus features that would be extremely practical for our use cases

  • Integrated pre-mixing and recording, so that you can quickly publish multilingual recordings after the event (but this could also take place in a kind of head unit per hall)
  • Optional auto-ducking/mixing (for output): If no mic is on, the original audio should simply be looped through, if at least one mic is on, the original audio should be “ducked” to an adjustable level
  • A loop buffer so you can “jump back” a few seconds (and would then slowly catch back up over the next minute or so)
  • Monitoring or recording outputs would be practical
  • Signaling to the mixing booth and to the stage would be convenient to e.g. to give the lecturers a “slow down” signal or the technicians “something is not right, but we cannot interrupt either, please come over” signal
  • Possibility of switching an external “on air” lamp or LED would also be welcome
  • Relay option, i.e. Multi-channel capability, e.g. if the stage audio is in German, there is an interpreter to translate DE -> EN, and a second, who receives the relay signal (EN) and translates EN->FR.
  • If you could insert a USB drive or SD card to configure the thing and e.g. could also send events to REST APIs, that would be a very nice bonus, as well as SSH access or Web UI or similar. 🙂

Some examples of different consoles, more or less fancy:

As you can see, all rather expensive, often with prohibitive licenses, and often not even available for non-businesses. We would like something that everyone can build or afford, so we can simply get a few for C3VOC and lend them out, something flexible, under open licenses, etc.

So, makers and hackers – I would love to talk to people who have a clue about audio hardware, especially DIY. I myself am more versed in concept, design and software, but I hope that nowadays something like this could be solved in a relatively affordable manner.

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