Open Hardware and Free Software: Teufel Mynd, a case study - FSFE

News<br>Open Hardware and Free Software: Teufel Mynd, a case study<br>on: 2026-06-29<br>Written by Nicole Faerber<br>The FSFE's volunteer and open hardware passionate, Nicole Faeber<br>read about the Teufel Mynd speaker announced as an "Open Source Project", so<br>she decided to put it to the test. We, the FSFE, bought<br>one and she dug in. Curious what she found? Read along with us!

Teufel Mynd Bluetooth speaker boxOpen hardware and Free Software are about more than tinkering:<br>they give users the freedom to inspect, modify, and truly understand the<br>technology they rely on every day. Open hardware means the design of a<br>device is publicly available: anyone can study how it's built, improve<br>it, or manufacture it themselves. Free Software goes hand in hand with<br>this: it guarantees that the code running on your devices can be use,<br>study, share, and improve by anyone. Together, they ensure that whoever<br>owns a device gets to decide what runs on it, free from manufacturer lock-in or<br>hidden restrictions.<br>This article has not been sponsored by Teufel<br>in any way. We bought the device to test from our own money and<br>did all research on our own.<br>In May 2025 the German audio hardware maker company Teufel<br>announced a new product, the Mynd Bluetooth speaker box. The<br>speaker in itself is yet another Bluetooth speaker box, the remarkable<br>feature of it is that it was announced as an "Open Source Project" with<br>"high repairability and sustainability", with all mechanical and<br>electronics design files as well as the firmware source code published<br>as "open source". So they mean the Mynd to be a Free Software and open<br>hardware product.<br>So we wanted to put this to a test!<br>TL;DR - A Quick Summary<br>The Teufel Mynd project is a pretty impressive example of an Open<br>Source Hardware project. All the mechanical and electronics design files<br>are made public under a permissive license granting the four freedoms -<br>to study, to share, to modify and to distribute modified versions of it.<br>The data is complete enough to recreate the whole hardware, the<br>mechanical enclosure as well as the electronics PCBs.<br>There are only two caveats:<br>The loudspeakers themselves are, at least very likely, Teufel<br>proprietary and Teufel does not sell them as spare parts.<br>The firmware for the Bluetooth module along with some DSP and USB<br>type-C controller firmware are not Free Software. But at least the files<br>are provided as binary blobs so one can build a complete firmware update<br>file.<br>So the project fulfills the Open Source Hardware Definition.<br>Let's dive into the details!<br>Repairability<br>Many current consumer electronic devices these days are not repair<br>friendly. Cost pressure and ease of mass production make the<br>non-repairable options, like glue instead of screws, very appealing to<br>manufacturers.<br>The Mynd is very different in this regard. The case is held together<br>by screws, not glue. The parts are pieced together tightly with proper<br>rubber seals, not glue strips. The screws are clearly visible and<br>marked, not hidden away under some sticker label or warranty seal. The<br>different screw sizes and types are documented on the bottom of device<br>itself. Also the starting point to pry the casing parts apart after<br>taking out the screws is marked on the case. So opening the device is<br>really made as easy as possible, no guessing, the steps for dis- and<br>reassembly are clear and pretty much self explanatory.<br>Mynd openedThere is just one caveat, availability of spare parts. So far Teufel<br>only offers the battery pack and carrying belts as spare parts, not the<br>Printed Circuit Boards (PCBs) or speaker chassis themselves. Maybe it is<br>possible to convince the Teufel service center to buy these, but<br>Teufel's general policy for spare parts says: "Please note: We do not<br>ship circuit diagrams, toner, or electronic components such as circuit<br>boards, capacitors, and resistors". For the average customer, this limits repairability.<br>Open Hardware<br>As promised in the product announcement, Teufel made all hardware<br>design files publicly available on GitHub. All these files are,<br>where applicable, licensed under the Creative Commons<br>"Attribution-ShareAlike 4.0 International" license which allows the four<br>freedoms: Use, study and modify, redistribute the original and<br>modifications.<br>This is pretty remarkable!<br>3D CAD, the casing<br>All components of the case are split into separate 3D CAD files and<br>are available in 3DM, STL and STP format. In total there are 11<br>different parts that make up the case / chassis. Here we have the main<br>case STP file opened in FreeCAD:<br>Teufel Mynd speaker opened and dismantledSo yes, everything is there, the full case and all its parts! Can you<br>remake it, like 3D print? Well, let's see, here is the front grill STL<br>file opened in the Cura 3D printer slicer:<br>This is looking pretty good! Since the Mynd speaker box is quite big<br>you of course need a large 3D print room, the front grill is 26cmx18cm.<br>But the problem is in the details. The...