Thursday, 24 July 2014

Build the Auduino Granular Synth - Part 1

Parts, Prepping and Drilling

In this tutorial we will take a look at building a stand-alone version of the Auduino Granular Synthesizer (pronounced AWE-duino not ARR-duino) and housing it in a spiffy looking custom enclosure. Even if you're not the musical type, the techniques outlined here may give you some inspiration for future projects so it is definitely worth a look.

Two flavors of the Auduino

Originally designed by Peter Knight for, this circuit is extremely fun to play with and will readily find a home in your arsenal of electronic noise makers. And since it requires only a few extra parts, it really provides a lot of bang for your buck. You can read more about it at the Auduino Wiki Page.

This tutorial builds on material we have covered in previous articles so if you are new, here is the path you should follow:

- Download the PDF files for the Drill Guide and Front Panel Art by clicking the links.

- Build the Arduino on a breadboard circuit described in this ARTICLE.

- Download the Auduino_v5.pde Sketch file from the Auduino page located HERE and program it into your chip as described in this ARTICLE.

- Transfer the circuit to the Adafruit Perma-Proto Board as described HERE.

Now that you are up to speed, Watch the following video for step-by-step instructions and exciting commentary by yours truly.

Here are the additional parts required

You can purchase some of the hard to find parts directly through the Notes and Volts Amazon Store

5 - Potentiometers - 4.7K (or 5K) - Linear Taper
5 - Knobs to fit the Potentiometers.
1 - Adafruit Perma-Proto board - 1/2 Size
1 - 1/4" Mono Phone Jack
1 - 2.1mm Power Adapter Jack (Fully Shielded)
1 - 9V DC Power Adapter (Rated at 50mA or more)
1 - Hammond enclosure - Model 1590BB (1590BBOR for Orange)
4 - Self adhesive Rubber Feet
3 Rolls - 22 Gauge Stranded Wire (Red, Green, Blue)

Photo Paper - (Matte finish)
Plastic Lamination Sheet
Double-sided foam tape or Velcro

Tools required

Drill bits (1/8", 5/16"*, 3/8"*, 1/2"*) *or sized to fit your parts
X-Acto Knife
Tape - (I use Scotch-Blue Painter's Tape)
Side Cutters
Soldering Iron

Optional (nice to have) Tools

Step drill bit that covers the drill sizes you need
Drill Bit Gauge (See video for details)
Automatic Center Punch
Helping hand soldering tool
Hack Saw

Check out Part 2 for the exciting conclusion!


  1. Please.... I don't still get the aim of dis project. I wud love 2build it koz it requires less components. Please could u explain?

  2. What do you not get?

  3. Check out my build here with MIDI:

  4. Great videos. I'm very new to synth DIY, but found this to appear doable with your great instructions. One question, is it possible to use a Makey Makey as the ISP? I have one on hand and remember that there is the possiblility of doing some Arduino functions with it, but not sure how extensive. Google didn't seem to turn up any results. Thanks.

    1. Hi MM. Thanks for the comment. I'm sure you will enjoy the project. I'm not familiar with the Makey but if it is truly Arduino compatible, you would need to be able to load the Arduino ISP program on it and have access to the MOSI, MISO, SCK, and RESET Pins like the Arduino.

    2. Thanks for the quick reply Dave. I can't find that info so I'll assume it can't be done and get the Arduino. Probably a good thing to have anyway.

  5. Question. I have like 4 UNOs sitting around collecting dust. I cod pull the ATMEGA328P out of one and order the passive components I don't have on hand and build the proto board circuit, like the instructions clearly explain. But can't I skip all that and just dump the code on to the existing complete Auduino, throw the UNO inside my Hammond BB, and use it's ready to go power input, and wire up the pots to the Auduino ? I really have four sitting and doing nothing and have already used three other UNOs , a Teensy 2, a Mega and a Leo on other stuff. It just seems silly to me to replicate a unit that I have to spare. Ordering the crystal, the power stabilizing components, etc... waiting for them to arrive and all that jazz would suck if I don HAVE to. I have the pots and jacks and knobs and wiring and the Hammond BB sitting right here.

    I guess my question is- will the sketch just "work" and are the pin assignments for the pots the same? Are there modifications to the instructions that I am too dumb not to see?

    And I figure that I am going to ruin an UNO by yanking the ATMEGA328P out of it instead of orderin a $5-$7 one and waiting - if I were to make the proto board one. And I don't have the crystal and the 33uf mylar capacitor - the only parts I don't have on hand.... so it's more of a patience thing. If I can just make it today by throwing the UNO in the Hammond BB, I want to make it today.


    1. Hi Pete. You can definitely use your UNO to build this. The original Auduino was basically this. Check out the instructions here:

      If you want to add the Line output upgrade and the MIDI mod, you will still need to add a board and some parts. Check it out here:

  6. hi can you send a Circuit diagram?

  7. I got mine to work, tough to tell with the not so good speaker. Really hard to put down once its all done I love it!

    1. Congrats Ben! Glad you're enjoying it. Great work!

    2. Hey Dave - now im thinking, can I use this same build, load different code for a different synth type result? I dreamt of making 1 unit out of 2 - 4 of these.....can you dig it?

  8. I have a few questions regarding to the logic..
    - Do you think it is possible to enhance the interrupt vector to handle 3 grains? (do you happen to know how much time does it consume now the signal() method). Does it make sense at all?
    - Can you explain or show some doc that explains the mapXXX() methods and arrays? Why exactly do you use those numbers?
    - Do you think it is possible to change the triangle wave to some other (like saw wave or rectangle -> enhancement for fill ratio), or even some sound sample?
    I plan to build a variant of this (using a Nano with a blown D3 pin) with my 10 yrs old daughter, I really like this project. Hope she will too when we build it... :)

  9. Hi Dave,
    a wonderful project - thanks publishing it.
    But, could you add some more information about the sketch?
    I do not understand very much of it (although it works very well) - and perhaps a video, where you explain the major parts of the arduino scetch would could be very helpfull?!
    Regards, Jazzman

  10. hi Dave, great project, love the sound. Is there any way to move the audio output to pin 9? I've tried to change the pwm pin on the code but I keep lossing control of my potentiometers


  11. Hey Dave,
    How quickly are are the analog inputs read and processed in software? I want to get rid of some of the pots and wire up some CV connections from modular synths. (don't worry about safe voltages and currents, I have it under control). I just want to know if I can modulate the sounds with a 1KHz sine wave or something along those lines.

  12. Awesome project! Although I tried to make it myself but the audio quality doesn't seem nearly as good as the one in your video. Plus when I turn up one of the pots, the sound changes completely but only when it reaches its max, like it couldn't handle it. any suggestions? I'm using 5K linear taper pots and double checked the connections.

  13. Hi Dave, it is really cool project - I've just made the box using all the exact parts like in your videos and it works. One question - coulc you shortly explain which know does what - in the same numbering, like in your videos: 23,24,25,26,27? Would be interesting what could be done when changing parameters of those in the code.

  14. I want to know if I can use Arduino nano with ATmega168 instead of buying crystals and making my own Arduino. If that's possible, do I need to change code or something? Thanks

  15. I want to know if I can use Arduino nano with ATmega168 instead of buying crystals and making my own Arduino. If that's possible, do I need to change code or something? Thanks