DIY Harmonic Mixer

How to Build the AI022 DIY Harmonic Mixer

This is the build guide for the AI022 DIY Harmonic Mixer Module

Buy the Harmonic Mixer Module

Table of Contents

  1. Resources
  2. About the AI022 Harmonic Mixer
  3. Tools Needed
  4. BOM (Bill of Materials)
  5. Build Guide

 

1. Resources

  1. Schematic
  2. Printable Build Guide
  3. Manual

 

2. About the DIY Harmonic Mixer

This DIY Eurorack Harmonic Mixer uses transistors and other discrete components to bring 1960s mixing technology to your Eurorack system. This mixer will add gain and harmonics as volume is increased, resulting in warm distortion, rectification, and even clipping when pushed. An exposed bias knob allows for more creative analog wave shaping, increasing harmonic content in your waveforms.

 

3. Tools Needed

For testing and Calibration:

 

4. BOM

Category Part Quantity Designation
Capacitor .1uF Capacitor 2 C 1-2
Capacitor 3.3nF Polyester Capacitor 1 C3
Hardware Shrouded Power Header 1 Power
Hardware Jack 4 In 1, 2, 3, Out
Nut Nut 4
Potentiometer 9mm Alpha Potentiometer A100K 4 P1-3, Master
Potentiometer 9mm Tall Trimmer B1K 1 Bias
Resistor 22K Resistor 3 R1-3
Resistor 15K Resistor 2 R4, 7
Resistor 150 Ohm Resistor 2 R5, 12
Resistor 2.2K Resistor 2 R6, 10
Resistor 120 Ohm Resistor 1 R8
Resistor 27K Resistor 1 R9
Resistor 47K Resistor 1 R11
Transistor 2n3904 2 T1, 2
Transistor 2n3906 2 T3, 4

5. Build Guide

  1. As usual, we solder from “low items to high items.” First solder the three 22k resistors.
  2. Now solder the two 15k resistors.
  3. Now solder the two 150 Ohm resistors.
  4. There are two 2.2K Resistors at R6 and 10.
  5. There is one 120 Ohm Resistor at R8.
  6. Now solder the 27K Resistor at R9.
  7. There is one 47K Resistor at R11.
  8. We’re done with resistors. Move on to the two .1uF Capacitors at C1 and C2.
  9. Now solder the 3.3nF Capacitor on the bottom side at C3.
  10. Now solder the shrouded power header. Solder one pin first, then reflow while you ensure the harmonic mixer is flat against the PCB. Make sure the alignment matches the picture.
  11. There are two 2n3904 transistors.
  12. There are two 2n3906 transistors.
  13. Now that we are donw with those we can solder in the jacks. I like to start with the ground lugs on the top side of the PCB to ensure they are flat, and then turn it over to finish them.
  14. Now solder in the four A100k Metal pots.
  15. Finally, solder in the B1K tall trimmer.
  16. Now perform a Continuity Test and power on.

Congratulations!

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If you are having any issues at all, please contact me at: https://aisynthesis.com/contact/.