Synthrotek OBEY - DIY Build
Coming in hot this month is our build of the Synthrotek OBEY eurorack module. This dual-function module is one half envelope follower and one half attenuverter or offset generator.
On one side of the module, the OBEY can take inputs from piezos, guitars, drum machines and even microphones to trigger an envelope or gate into your eurorack system. The other side of the Synthrotek OBEY can attenuvert voltage sources in both positive or negative values (up to 2x times), giving this tiny module some hell of an impact on your performance/recordings.
Born from the Synthrotek nano series of modules, the OBEYs footprint is only 4HP wide. It has 4x LED sliders that control the various two sides of the module. Now, judging by our description, it seems overwhelming and complicated to use. It is not. Synthrotek has provided a lot of documentation and there are several YouTube videos out and about that show the OBEY being utilized.
NOTE: You can access the build docs and the manuals below in our “Quick Links” section below.
Let’s get on with the build shall we?
Upon unpacking the module, you will notice that it comes with 2x PCBs and 1x panel. Set the smaller of the PCBs aside (it’s the control board that you mount jacks, sliders, etc to) and pick up the logic board. This is where we will start the build process.
Diodes and resistors are first up. Make sure to place the diodes the correct direction as stated on the PCB and the BOM. This is essential since they are polarized. The resistors, be it all of them are non-polarized, meaning you can place them in any direction you choose. We used our resistor bend tool from our Synth DIY Tool Set to help bend the resistors to the perfect size prior to placement.
After all of these components are placed, you can either use a top down soldering technique or you can flip your board and solder from the bottom of the PCB. We used top down as it was just quicker and the boards soak up solder quickly.
OBEY - Time Lapse Build
After the diodes and resistors, we move onto IC sockets being careful to place them as they match the silkscreen on the PCB. Once those are tacked down, the ceramic caps, transistors, power header and voltage regulators are up next. Make sure to leave a little room on the ceramic caps so that you can tack those down ensuring that the legs touch the PCB pads. The 10-pin power header is also important to mount the correct way … if not, you could fry your module.
Electrolytic capacitors are next and they can be tricky. Just remember that these are polarized and its important to place the LONG leg of the cap into the hole that has a ‘+’ symbol next to it. If you do this the wrong way, say goodby module. Follow the electrolytic caps with the DIP switch. Don’t worry about setting the switches now, we will get to that later. You are done with the logic board.
The Control Board...
Grab the control board and mount the 5×2 angled board headers. Pay special attention that the header pins that are straight go through the control board and are sitting flush. After they are tacked down, flip the board over and clip the excess solder from the board. Just to be on the safe side, we covered our clipped pads with Kapton tape so that when we placed the sliders, there would be no contact anywhere.
Once this is done, move onto the sliders, switch and jacks. Place the parts on the control board and them temporarily mount the panel so that you can line everything up. Solder at least 1 or 2 of the legs on the components and grab the logic board. It’s now time to marry the boards.
Wrapping it all up...
Carefully, place the control board 5×2 header pins into the logic board. Once they are aligned like you want them to be, tack down one pin to hold everything in place. If you need to, re-heat the pin to move the board around so that it is to your liking. Insert the IC’s into their sockets by matching up the dot on the chip to the notch on the socket or PCB silkscreen. Attach your 10/16 pin ribbon cable and head on over to your rack … you have just completed the Synthrotek OBEY.
We do recommend doing a quick test of the module to ensure there are no shorts. In our case, we utilized our Synthrotek TST module that we had previously built, and everything came out ready to rock!
Features and Specifications
- Dual Function Controls
- Works with CV or Audio signals
- Works with a wide variety of input signals
- Offset Generator
- Works with + or – voltages
- Envelope Follower
- Small footprint (only 4HP)
- Power supply: +/- 12V
- Power connection: Eurorack 10-pin shrouded header
- Current draw: 25mA (+12V) / 18mA (-12V) / 0mA (+5)
- Module Height: 3U
- Module Width: 4HP
- Module Depth: 48mm
OBEY Purchasing Options
Synthrotek has a couple different options when it comes to purchasing the OBEY module. We wanted to keep it simple by just placing images of the options and linking out to the direct purchase. The prices are excellent and the quality of this build is way worth it! Head on over to SR and tell them we sent ya!
- OBEY Manual
- Quick Start Guide
- Assembly Instructions (DIY KIT)
- Bill of Materials (DIY KIT)
- Synthrotek Store Page
Our Final Thoughts . . .
This was a fun little module to not only build but to jam with in our rack. We haven’t had a lot of time to play around with it and to run it through all the paces of external equipment, but from what we have, its rad. The build was easy, but one needs to really just take their time. Total build time was less than an hour in our shop, whereas it might take the novice builder a couple hours to complete. Aesthetically, the LED sliders are slick. They are not too bright and they do not over power the visual looks of the module.
For 4HP and the unlocked capabilities of this module, this one is a no brainer to add to your rack. The prices are right and the documentation is clear and concise thanks to Synthrotek. (reminder – you can find them all up above in our “quick links” section). Head on over and pick one up, you won’t be disappointed!
Comments or Suggestions?
If you have questions about the build process or suggestions/feedback about this article, feel free to let us know by contacting us We look forward to hearing from you!
Until the next build …