Freesound goes Eurorack Hardware with CTAG Strämpler

[Guest blog post by Robert Manzke alias rma31]

Hi, my name is Robert, some 6 years back I have founded the academic working group “Creative Technologies AG” (CTAG) at Kiel University of Applied Sciences in Germany.
In the domain of Audio, we engage students and form international collaborations.
Our focus is music technology and production, sound synthesis and design and adjacent areas such as electronics, computer graphics, algorithms, related hard- and software, maker technologies, human machine interaction, immersive art and media and so forth…

Also, I got my first Freesound t-shirt on June 2nd 2009 and have always been a great fan of the Freesound idea, to create a social and open platform for sounds and its use in science and education.

Since the existence of CTAG, there have been several student teams involved with the Freesound API to interact with the sound data base. Most notable results include the Beaglebone single board computer based sampler “Beagle Boom” and, very recently, the Eurorack sample streaming module “CTAG Strämpler”:

Strämpler harware UI
CTAG Strämpler.

CTAG Strämpler (half streamer, half sampler therefore “Strämpler”, which is close to the German word “Strampler” meaning romper suit) is an electronic sound synthesis module designed for Eurorack modular synthesizers.
Most importantly, it has internet access with connectivity to the Freesound API, making the Freesound sound data base accessible through hardware. One can download sounds to the module’s SD-card and play them back as two separate voices.
Typical parameters such as pitch and amplitude can be influenced, just like one would do with a sampler. It includes a comprehensive control voltage (CV) matrix, where external CV signals can modulate various sound parameters. Some basic effects such as a stereo delay and low/highpass filters are implemented as well.

The firmware and the DIY hardware design are entirely open source and available on Github. CTAG is currently looking for collaborators to further develop the Strämpler. One highly desired feature would be the ability to sample your own sounds within your Eurorack setup with Strämpler and share them instantly on Freesound, actively contributing to the sound data base. More details can be found on hackaday and the projects web-page.

CTAG Strämpler demonstration video.
CTAG Strämpler latest PCB revisions in the works.

Both above mentioned projects were related to hard/software projects by students as part of their regular curriculum. Doing such practical projects allows us to teach students immediate application of web-programming (Freesound API), time-critical real-time audio programming and application of digital signal processing, soft/hardware UI design and implementation, hardware near programming and design, debugging of complex systems etc. Students greatly deepen their abilities during these practical projects and are highly engaged. They also learn how to reach out and inform the world about their work (social media, github, Freesound, open source concepts, etc.).

Apart from the Freesound related project, there have been numerous other projects at CTAG, mostly with a strong penchant towards the open source community; our purpose is to give back knowledge to the society as being associated with a public university in Germany. Students also benefit of a continuously growing pool of partnerships with other academic institutions (Erasmus+ exchange) and private companies. CTAG is also a strong advocate for startups in the music-tech domain and we are proud to have helped Instruments of Things to become alive.

We always look for opportunities to collaborate and wish to further support Freesound with our applied research, just get in touch with us 🙂 …

— Robert Manzke


Robert Manzke developed his passion for electronic music starting age 5 (the record was Vangelis Heaven and Hell, his first synth was a Korg Poly 61).
It lead him to successfully study electrical engineering and digital signal processing. He obtained a Ph.D. in computational imaging sciences at King’s College London in 2004 and worked for Philips Research USA in the field of medical imaging afterwards.
He left that field in 2012 and joined Kiel University of Applied Sciences as Professor for Ubiquitous Computing. Since then he focuses on his passion of music technology within the Creative Technologies working group (CTAG).

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5 Responses to Freesound goes Eurorack Hardware with CTAG Strämpler

  1. cabled_mess says:

    Wow, that’s so cool!
    Love the healthy amount of CV-inputs.

  2. Evgeny magata says:

    I really wish I had a eurorack system, this is extremely cool!

  3. johnstamos says:

    such a grand idea made into reality!

  4. Cesar Rodrigues says:

    Now I am even more tempted to get a modular!…

  5. Don Richard Sam says:

    Dazzled by this innovation. I will look for the device and get one in due course.

    Dread!

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