Hey lines! Some of you may be interested in this project I was finally able to release.

Schräg is an expanded repackage of the Bastl Cinnamon multimode filter, released with their permission as an open source project.

More information on the github repo: GitHub - barnabywalters/Schraeg: An 8HP eurorack multimode filter module based on the Bastl Cinnamon

The filter core works exactly as the Cinnamon, with the following new features:

  • 8HP form factor, allowing for larger character and gain switches and a big juicy cutoff knob
  • Voltage control over resonance, through an attenuverter (using the two unused VCA cells from the original design)
  • A new FM input through an attenuverter, which works as a pitch fine-tune control with nothing patched
  • A bi-directional power connector with polyfuses
  • An Interactive HTML BOM to aid in part placement

With this release comes a request and an offer:

The released board layout is the second revision, with various small issues from the first run I ordered fixed. The DRCs pass, but I haven’t yet ordered or built the latest version, and am unlikely to do so myself in the near future as I already have spare boards from the first run, don’t need 20 Schrägs and am not interested in selling built modules. So if anyone out there likes the concept and wants to order and test a run of the new boards, I’d greatly appreciate feedback and would be happy to help with the process.

And the offer: Update: all the spare boards are claimed now.

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This is really cool, thanks for sharing!
Nice to see that you’re using Kicad. It will be cool to open up your design and explore it a bit; I recently learned how to use it and have been wanting to look at other peoples eurorack designs.

I actually also recently did a SMD rework, in this case of the Bastl Kompas module (thank you for the open designs Bastl folks!). I’ve been meaning to share my work and your post motivated me to clean up the resources. I figure here is a relevant enough place. It can be found at ~philomates/kompas - sourcehut git.


Here is a shot of an early prototype with a quick panel cobbled together.

The Kompas is a pretty versatile little module: 3 pots, 3 CV in, 2 gate in, and 3 gate out. I’ve been having fun writing alternative firmware, like a windowed comparator and a probabilistic latch/burst generator, all of which are also in that linked repository. It can also run firmwares written for the Grains Ginko Synthese, so basic sound generation stuff is possible, though there isn’t PWM smoothing filter in the kompas.

Hardware-wise I adapted the original design a bit to expose serial pins. With this I was able to use this module as the basis for some other designs, like a Befaco Muxlicer clone that includes capacitive touch buttons for selecting the step and sequencer mode.

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Cool! The expansion possibilities with the serial port sound very interesting. Does your module’s logic board just sort of hang off the module on cables, or is that a temporary measure?

I’ve always been a bit surprised that so many open source synth and electronics projects use Eagle rather than KiCAD. KiCAD has its annoyances but as far as I can tell is comparatively capable, and doesn’t force you to have an account and internet connection to use it.

I’m no electrical engineer, and wouldn’t recommend treating my boards as a good example of… anything, really, but I’ve learned all the essentials like managing hierarchical schematics, making custom footprints etc. The one big KiCAD tip I can give is to check out the Interactive HTML BOM plugin. IMO that alone makes KiCAD worth using for DIY/open source projects.

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unused 2164 to Q is nice.

good to see bastl’s modules
i made a few bastl modules via point to point soldering.


dynamo 4HP

hendrikson 4HP
popcorn-vorne popcorn-dorsal2
popcorn + expander 10HP

cv trinity + expander 10HP

kompas 4HP

no fotos, but also made propust 2HP.
always thanks bastl instruments for open-source schema and supports.

9 Likes

yeah, it is a bit of a mess, but fine for prototyping


In essence the extra pins from the Kompas power a MPR121 capacitive touch chip as well as some 8-channel multiplexers that allow for setting up a nice little sequencer. If I ever ended up doing a 2nd revision I would roll it all into one board to clean it up.

1 Like