Synthrotek AstroNoise - DIY Build

Inspired by 80’s chip tune drum machines, the Synthrotek AstroNoise contains 3 different vintage tones that can give your track something its been missing. Originally released as a DIY project for Knobcon, the AstroNoise came into the world of modular last year in all of its nostalgic glory.

Since we could not make it to Knobcon 2021, we were thankful that this kit made it into the wild. Let’s get on with the build!

The Build...

Upon cracking open the kit, the novice builder could be overwhelmed by the number of things going on. Multiple ICs, bags of LEDs and switches and pots that are not labeled. Synthrotek includes the BOM with their kit and it also available online if that is easier to access. This is essential in building this kit, as well as having a way to test resistors in case any of them got shuffled in the packing or shipping. First things first; start by separating everything (make sure to keep the LEDs in their bags until you get to that part of the build)

When you have everything sorted, you will notice that there are 2 PCBs. One is the control board where the jacks and switches install and the other is the logic board, which contains a sea of white screen print. We will start with the diodes first. The diodes are polarized, so make sure to populate them with the cathode stripe in the same direction as indicated by the silkscreen. If you flip these around the wrong way or leave your iron on the component for too long, you can damage the module. Tack these down either using top down soldering or by flipping the boards over to access the solder points. 

fin Divider

IC Sockets, Power Socket and Headers (Logic Board)

Next up are the IC sockets. Take care when populating these to not bend any of the legs. Line up the notch at the end of the socket with the notch on the silkscreen. (This notch indicates where pin 1 of the IC is). When you have them populated, carefully flip your project over and solder everything in place. While you are here, tack down the power header as well. You can use the same heat and click method that is mentioned below.

Builders Note: A trick to getting IC sockets and power headers to lay nice and flat is to only solder one or two pins of each socket, and then reflow the solder joint while gently pushing on the top of the socket to seat it flat against the PCB.

Synthrotek AstroNoise - Time Lapse Build

Play Video

Resistors (Logic Board)

The resistors are up next and they will be placed in an upright position due to the size of the PCB and orientation of the circuit. Since they are not polarized, you can mount these in any direction you wish; just make sure one leg is totally bent down and the other is left straight like it comes. Sometimes the resistors get shuffled around in the packing/shipping process. We used a component tester to ensure we had the right value when referring to the BOM.

Capacitors, Trimmer and Transistors

Now we can populate the ceramic capacitors. These are non-polarized and can be inserted either direction. If the capacitor coating runs down the legs a little, make sure the coating doesn’t poke into the pads. Once they are in, carefully flip over your project and solder them in place, clipping the excess leads. 

The electrolytic capacitors are polarized, so take care to ensure that the longer leg (the leg that is further from the stripe indicator on the body) goes through the solder pad with the little ‘+’ symbol next to it. Once it is aligned properly, carefully flip your project over and solder it in place, clipping the excess leads on the bottom. Go ahead and tack down the resistor trimmer and then take a break, as you just completed the logic board (minus the ICs).

AstroNoise - Build Gallery

LEDs (Control Board)

The LEDs are the beauty of the Synthrotek AstroNoise and you will need to take care when lining them up. Populate the LEDs by placing the LONGER lead into the pad that has a “+” next to it and carefully flip the board over and tack them down. We found that placing one color at a time and bending one lead so that we could solder the part into place worked best. You can also heat up the pad and gently push the LED flat against the PCB. Continue with the other colors moving down the PCB until all of the LEDs have been completed. 

Headers (Control Board)

Previously you had mounted headers onto the Logic Board. These headers will correspond with the headers on the Logic board and will be used to connect both of the PCBs together (along with a screw or two). The easiest way to make sure that the boards align correctly is to use the Logic Board as a guide by simply placing the boards on top of each other. After the boards are lined up, solder the header pins on the Control board. Go ahead and screw down the standoffs at this point as well once you have separated the boards to continue the Control board population. 

Jacks, Pots and Switches (Control Board)

Carefully place the jacks into their positions and tack down the ground pin to keep them from moving. (do not solder the other pins just yet). Next, place the switches according the BOM and not they are both different types of switches. One switch is ON-ON and the other is ON-OFF-ON. When placing the pots, you will also want to refer to the BOM to make sure you put the right pot into the right place. 

Panel Placement and Wrap Up

Now take the panel and place it onto the Control Board. Tighten down the nuts on the jacks and the switches to ensure that the parts are held in place. Flip the board over and solder everything, completing the board. Lastly, prior to placing the knob, connect the two boards together and snug them up with the standoff screw. Double check your work, attach the spaceship knob and set the ICs prior to testing. You will want to refer to the BOM again to make sure you put the right IC into the correct socket. 

fin Divider

Features and Specifications


  • Tone Select Switch lets you choose between three sounds: oscillator, noise and sub-oscillator
  • Rate changes the master frequency/rate
  • CV over Rate (tracks 0-5V, not 1V/O)
  • Decay control and Trigger input
  • Amplitude of the output is relative to the voltage coming into the trigger input, allowing for a more dynamic output
  • Two LFOs with an LFO Level control
  • LFO On/Off switch
  • Trimmer on rear of module for attack cycle
  • Retro spaceship knob and panel design


  • Module width: 6HP
  • Module depth: 35mm
  • Current draw:
  • +12V: 130mA
  • -12V: 10mA
  • Comes with power cable, 2.5mm and 3.5mm screws
fin Divider

Synthrotek AstroNoise - Purchasing Options

Synthrotek has a couple different options when it comes to purchasing the AstroNoise module. The prices are excellent and the quality of this build is way worth it! If you are interested in buying the kit or the assembled module, click on the images below and you will be redirected to their site to purchase! Make sure and tell the gang at SR that we sent you!

AstroNoise - Assembled Module
AstroNoise - Full DIY Kit

AstroNoise Audio Demo

Here is a short audio demo of the Synthrotek AstroNoise. In the demo, we only use the 

Our Final Thoughts . . .

Noice builders can complete this module but they might find it intimidating with all of the ICs and standing resistors. Transistors and the LEDs can also be tricky and one needs to take their time when placing/soldering them into place. We used top down soldering for some of the build to help hold things in place when flipping the PCBs over. Intermediate and advanced builders shouldn’t have any problem with the build and it can be completed in about an hour tops. 

In the end, the Synthrotek AstroNoise is just a cool module. The LEDs really bring the module to life and with its 80s inspired chip tune sound, it feels like you are traveling back in time. Even without patching the module, you can get some crazy sounds from it as you can hear from the audio demo above. We might just have to order up another to see what kind of randomness we can achieve! AstroNoise has won its place in our rack and it will in yours too. 

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

fin Divider