Cereal Instruments 'thump' - DIY Build

Cereal Instruments - THUMP - Completed Front

Cereal Instruments ‘thump’ allows you to send two signals through a gritty vactrol amp with low pass gate modes & plenty of gain/distortion. Sounds cool huh? We thought so too and thought it only made sense that the ‘thump’ was our next build. One thing to note is that the ‘thump’ is unlike its brethren kin with regard to power. It is Cereal Instruments first active module, meaning it requires power to operate unlike the ‘mesh’ or ‘swerve’.

The ‘thump’s aesthetics are a matte black panel with orange knobs and white silkscreen give the modules their own unique look. The PCBs that Cereal Instruments uses are excellent quality. They soak up solder like a sponge grabs water. This makes for a stress free build. Speaking of the build, the ‘thump’ would be recommended for intermediate builders and above.

Novice builders could struggle with some of the tight spaces, double PCB layout and the giant pot/switch that needs to be wired in a specific manner in order to get the correct switching.

Let the soldering begin…

Since there are 2 PCBs, start with the logic board first. This is the one that doesn’t have the jack/pot mounting spaces (that is the control board). Resistors, diodes and caps were first up (one cap will be placed on the control board). We used top down soldering instead of bottom soldering due to the ease of access. After these were tacked down, the IC sockets were next. 

Dab one pad with solder and then line up the IC socket with the holes. Heat up the solder and lightly push the IC socket into the melted solder. This will hold everything in place when you turn the control board over and complete the IC socket soldering.  

The main power header is next followed by the standoffs and the electrolytic cap. This capacitor is soldered on the backside of the logic board.  Lastly, attach a wire from the top CV jack pad to the outer CB pot pad as shown in the photo below.

Detailed - Install Wire
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Lights and more lights...

Prior to moving onto the control board, we have a one more component on the logic board. The vactrol is the last piece to tack down and it is really important to make sure you have the correct orientation. After placing the vactrol, jump to the control board. You will want to grab the x2 trimmer pots, LEDs and standoffs. Trimmer pots are a quick solder as well as the stand offs on the backside of the control board. LEDs have polarity and its important to pay attention to which way they are oriented.

The cathode (negative/short leg) will be placed into the square solder pad, whereas the long leg (anode) will be placed into the circle pad on the PCB. 

'thump' - Time Lapse Build

Play Video
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'thump' PCB Version Changes v1.2.2

Next up is the switch. This is the large potentiometer looking component with all the connection points on the bottom. It is very important here to match the layout of what you see in the photos. If you fail to do this, the module will not function correctly. The cool thing is that Cereal Instruments supplies the wire needed to hook up the switch and as long as you match the layout, you will be golden. Try to cut the wires around the same length. You should have some of the blue wire leftover which you will need if you have PCB version v1.2.2. We will get to that in a minute. 

After the switch has been wired/soldered, set the logic board aside and grab the small heat shrink tubing that was in the kit. Trim this down to the size of the LED and place it around the LEDs. Use your iron and shrink the tubing around the LED so that it will keep the light from bleeding into other modules. Once you are done with this, its time to make a few additional connections. Start by connecting a wire between the center leg of the amp CV pot and the third pin from the right as shown in the galleriy below. 

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Manufacturer Links:

The Build Continued...

Pick up the control board and place the jacks and the pots, paying special attention to the pots and ensuring they are in the correct position/value. Once these are in place, attach the stand offs with the supplied screws after inserting the ICs. It is very important to make sure the ICs are placed in the correct orientation too (photo in the gallery above).

Now that you have completed both the logic board, control board and the switch, it is now time to put it all together and start using your new Cereal Instruments ‘thump’. Start by lining up the pots and the jacks on the panel and place those. Hand tighten the nuts on each to hold the panel in place. After this is done, its the switches turn to be mounted. Slowly place it into the upper most hole in the panel.

Wrapping it all up...

Tighten everything down; we suggest using our Synth DIY Tool set to get the job done without scratching your panel. Time to grab the orange knobs and place them accordingly. It’s pretty easy to tell where they all go based upon their size. 

Time to take a breath and pat yourself on the back. You have now completed the Cereal Instruments ‘thump’ and its time to calibration. We have included screenshots from the YouTube build video so that you can see what needs to be done. Make sure and follow them as required.  

Final Thoughts...

As for the build and the module itself, we would consider it an intermediate build for a couple of reasons: 

  1. the multiple PCBs – this can be intimidating to some builders
  2. if you have PCB version 1.2(.2), you have a few more extra connections to make. 
  3. there is no actual build guide besides a video and the only documentation included with the kit is the BOM. 
  4. the switch…. take your time. 

Overall, we know the ‘thump’ is a solid module…. in fact, everything that Cereal Instruments makes is. This vactrol based module will provide us hours of distortion and we know we are going to love it. We highly recommend picking up the ‘thump’ and any of the other modules made by Cereal Instruments over at their Reverb shop. If you decide to pick one up, make sure to let them know that we sent ya. 

At the time of this build, we haven’t had a lot of time to go into patching the Cereal Instruments ‘thump’ but we intend to soon. You can watch a demo video from the CI YouTube page, as well as a couple others on the internet.

Once we have some more time, we will be posting a demo or two and will update our social media pages accordingly as well as here on our main site (make sure to bookmark). Stay tuned for audio demos and patching videos of the Cereal Instruments ‘thump’ here in the near future and until the next build… 

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 … 

~ f i N

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