This build is a beginner level build, but with a few surface mount components. However, this is a good project to get into surface mount components, and an otherwise simple build.

Do this before building this module:

  • Check that you have all components.
  • Gather all the tools needed (see lists below).

The tools needed for this build are:

  • Soldering station or soldering iron.
  • High quality solder (lead free recommended).
  • Fine tipped side cutters.
  • Round-nosed pliers (for bending component legs).
  • Angled tweezers for surface mounting.

Recommended accessories:

  • PCB holder (makes life much easier).
  • Breadboard.
  • Knurled Nut Driver Tool (for tightening jack socket nuts).

Got everything? Let’s get on with it!

1. ICs

Begin by soldering the surface mount operational amplifiers TL072 (U1, U2, U3). Take care to mount them in the right orientation, see image for reference.

2. Resistors

Solder all 100K resistors (R1, R2, R5, R6, R9, R10, R13, R14, R17, R18, R21, R22).
Solder all 47K resistors (R3, R4, R7, R8, R11, R12, R15, R16, R19, R20, R23, R24).

2. Capacitors

Solder the 100nF ceramic capacitors (C3, C4, C5, C6).
Flip the board over and solder the 22uF electrolytic capacitors (C1, C2). Make sure to check the polarity twice before soldering, the long leg must go to the hole with the plus symbol! See image for reference.

3. Diodes

Solder the 1N5819 schottky diodes (D1, D2). Make sure to check the polarity twice before soldering. See image for reference.

4. Headers

Flip the board over again and solder the 2×5 pin header for the eurorack power connector.

5. Jacks sockets and potentiometers

Place all the 100K potentiometers (VR1, VR2, VR3, VR4, VR5, VR6) and the jack sockets (IN1, IN2, IN3, IN4, IN5, IN6, OUT1, OUT2, OUT3, OUT4, OUT5, OUT6). Do not solder them yet!
Attach the front panel and hand tighten the nuts on all of the jack sockets. Make sure everything is straigth and correctly seated, and solder all the joints for the potentiometers and jack sockets. When you are done soldering, tighten the nuts for the jack sockets with an appropriate tool. You are now done!

6. Powering up and testing

Connect a 10-pin eurorack power cable to the power socket and attach the module in your eurorack case. Connect a signal to one of the inputs (for instance a sawtooth wave from an LFO) and feed the corresponding output to a module (for instance the FM input on a VCO). Set the potentiometer to 12 o’clock. There should be no signal going through the attenuverter. Increase the level and there should now be a sawtooth signal going through. Decrease the level and there should be an inverted sawtooth (ramp) going through the attenuverter.