Introduction: Zynthian: Open Synth Platform (Zynthian Basic KIT V2)

Zynthian is an open project with the goal of creating an Open Synth Platform based in Free Software and Open Hardware Specifications & Designs (when available). It's a community-driven project.


This tutorial is based on Zynthian Basic Kit v2, that can be find in Zynthian Shop.

Other KITs are also available if you are a musician or aficionado and your electronic skills are limited. Take a look into Success Cases.

Step 1: Bill of Materials, Required Skills and Tools

Bill of materials

  • Zynthian Basic Kit (custom PCBs, electronic parts, wiring and knobs)
  • Case Kit
  • Raspberry Pi 3 (or Raspberry Pi 2)
  • HifiBerry DAC+ souncard
  • OzzMaker PiScreen 3.5" touch-display
  • Power adapter for Raspberry Pi (5.1v 2.4A with microUSB connector)
  • 16GB SD Card (a good one, please!)

Required Skills

For building the hardware you should have the following basic competences:

  • Soldering
  • Basic understanding of reading basic electronic circuit diagrams
  • Enjoyment of work with electronic hardware and parts


And this is the list of required and recommended tools:

  • Soldering iron
  • Tin-solder
  • Wire-cutter
  • Small Plier
  • Screw-drivers Philips
  • Wrench, for potentiometer nuts (recommended)
  • PCB holder for soldering (very recommended!)
  • Small iron brush (very recommended!)
  • Magnifiying glass (recommended)
  • A vice (recommended)
  • A hand saw for metal (recommended)
  • Multimeter (recommended!)

Step 2: Assembling the Controller Modules

The controller module kit is composed of:

  • 4 x controller PCBs
  • 4 x rotary encoders with switch (PEC11R-4215K-S0024)
  • 4 x ceramic capacitor 100nF (C1)
  • 8 x ceramic capacitor 10nF (c2, c3)
  • 4 x 4-pin JST male-angle connector

This components are used to build the 4 controller modules that form the input side of the physical Zynthian User Interface. Each controller embed an incremental rotary encoder and a switch, so 4 wires (A,B,SW,GND) are needed for connecting it.

These are the steps for building one module:

  1. Bend the encoder's securing tabs to 75º, so you can insert it in the upside of the PCB (the labeled side!). Please, be very careful when bending the tabs as the encoder case is quite fragil and could be deformed. I recommend to use a small plier and not reaching to 90º.
  2. Place the 100nF capacitor in C1 position (the most right!). This is for debouncing the push switch (SW).
  3. Place the 2 x 10nF capacitors in C2 & C3 positions. These are for debouncing the rotary encoder contacts (A,B).
  4. Solder the encoder and capacitors carefully.
  5. Place the JST connector in the downside of the PCB, with the angle pins facing inwards (look the photo!)
  6. Solder the JST connector carefully.
  7. Use the plier to close the encoder's tabs again, trying to "catch" the PCB.

You have to build 4 controller modules, so you to have to repeat the steps 4 times.

Step 3: Assembling the All-In-One Module

The All-In-One module kit is composed of:

  • 1 x All-In-One PCB
  • 1 x GPIO-expander MCP23017 => 28-pin IC
  • 3 x opto-coupler H11L1 (OC1,OC2,OC3) => 6-pin IC
  • 3 x diode 1N4148 (D1,D3,D4)
  • 1 x diode 1N5819 (D2)
  • 3 x resistor 1K (R3,R4,R9) => brown-black-red (*)
  • 1 x resistor 10K (R10) => brown-black-orange (*)
  • 1 x resistor 100 (R1) => brown-black-brown (*)
  • 2 x resistor 4K7 (R5,R7) => yellow-purple-red (*)
  • 3 x resistor 470 (R2,R6,R8) => yellow-purple-brown (*)
  • 4 x ceramic capacitor 100nF (C1,C2,C3,C4)
  • 7 x 4-pin JST male connector
  • 1 x 40-pin-double-row male connector

(*) Read from left to right with the tolerance ring (gold or silver) on the right.

These are the steps for building the All-In-One module:

  1. Place the passive components (resistors & capacitors) in the upside of the PCB (the labeled side!).
  2. Solder the components carefully. Always avoid overheating!
  3. Place the ICs and diodes in the upside of the PCB (the labeled side!). Put attention to the orientation of these components!!
  4. Solder the components carefully. Always avoid overheating! (*)
  5. Place the connectors in the upside of the PCB (the labeled side!).
  6. Solder the components carefully. Always avoid overheating! (*)

(*) You could use some tape for fixing the components while soldering, specially for ICs and connectors.

Step 4: Tweaking the HifiBerry DAC+ Soundcard

If you are using the HifiBerry DAC+ soundcard (also lite & pro versions), you should add 2 extra connectors to the board:

  • 40 row-pin GPIO male connector, for connecting the main ribbon bus cable
  • 3 pin header connector, for connecting the extra audio line-out Jack connectors

Both connectors must be placed on the top side of the board, so you should solder the contacts on the bottom side.

WARNING! Soldering the big 40-pin connector can be difficult if you don't have enough practice.

Step 5: Tweaking the OzzMaker PiScreen 3.5' Touch-display

The standard OzzMaker PiScreen 3.5 'touch-display have 2 connectors: a female connector ready for connecting the display as a hat and a male connector placed in the side. The official aluminum case and the ribbon cable are designed for the side male connector. The female connector can be annoying and should be removed for better closing the case.

If you got your PiScreen from a "Bundle-All" kit, you probably don't have this annoying female connector, so you are lucky and don't need to do anything here. If you have it, then take the saw and remove the connector carefully.

Other Soundcards and Displays
If you are using a different soundcard or display, you'll have to see the best way to integrate it.

Step 6: Building the MIDI-IN/OUT/THRU Connectors

Before mounting the MIDI-IN/OUT/THRU connectors into the case we will solder the needed wires that allow connecting it to the All-In-One circuit using a JST connector. Doing it in that way is rather more comfortable than trying to solder inside the case with all the wiring mess.

JST Connector wires

  • JST White (1) => LED's Anode (LED's red wire/long lead)
  • JST Yellow (2) => LED's Cathode (LED's black wire/short lead)
  • JST Black (3) => pin 5 of MIDI connector
  • JST Red (4) => pin 4 of MIDI connector

If you want (i strongly recommend you do it!), you can protect the contacts using heat-shrink sleeve (the red sleeve pieces in the photo). In that case, remember to insert the sleeve pieces before soldering ;-)

Step 7: Building the JACK Audio-Out Connectors

In the same way, before mounting the Jack connectors into the case we will solder the needed wires. You can use heat-shrink sleeve too.

Step 8: Mount the MIDI Activity LEDS

Insert the 3 LEDS in the case holes. You may want to push the LEDs with something more rigid than your finger. The screwdriver's handle could be fine.

When it's done, you have to solder the 2 LED wires (red/black) with the 2 spare wires on the MIDI JST harness (white/yellow). Polarity is important, so don't cross the wires:

  • JST White wire (1) => LED's Anode (LED's red wire/long lead)
  • JST Yellow wire (2) => LED's Cathode (LED's black wire/short lead)

After soldering all the 3 LEDs, you may want to protect the connection with heat shrink sleeve, adhesive tape or hot melt glue.

Step 9: Case Mounting (optional)

If you use Zynthian Aluminium Case Kit, that is compatible with Zynthian Basic Kit v2, you can follow next steps (you will find the detail steps here):

Assemble the Main Computing Block
The main computing block is composed by the RBPi and the HifiBerry soundcard.

Secure the Main Computing Block
After assembling the main computing block, you should secure it to the case. Use 4 black M2.5 bolts

Secure the All-In-One module
Secure the All-In-One module to the case using 4 x separators and 8 x M2.5 bolts.

Secure the Jack connectors
Put the rings on the outer side of the case to avoid damaging the case surface when you tighten the nuts.

Secure the MIDI-IN/OUT/THRU connectors

Just insert the connector with the JST-wire from the out-side of the case and the nut from the innerside. A pair of pliers can be useful for tighten.

Mount the MIDI activity LEDS (describe above)

Secure the Display

It's composed of 4 bolts, 4 nuts and 4 nylon separators. Before fixing the screen, don't forget to remove the protective plastic sheet.

Secure the Controllers
Fix the 4 controller modules to the case cover using the 4 bolts and washers attached to every rotary encoder. IMPORTANT: For avoiding problems while closing the case, i recommend to mount the controller modules with the connectors facing one another.

Insert the knobs
You should insert the knobs into the encoders before closing the case. This will avoid forcing the encoders too much as otherwise, you could break them.

Step 10: Connect the Main Ribbon Bus

Connect the Main Ribbon Bus cable to the RBPi's 40-pin header and also to the All-In-One module

Step 11: Connect Controllers on the All-In-One

Connect the 4 double JST cables to the 4 controller connectors on the All-In-One module (CTRL1, CTRL2, CTRL3, CTRL4)

Step 12: Connect MIDI

Connect the 2 JST cables from the MIDI connectors to the MIDI-IN, MIDI-OUT and MIDI-THRU connectors on the All-In-One module.

Step 13: ​Connect the 4 X Controller Modules

Connect the 4 x Controller Modules following the right numbering: from top to bottom and from left to right.

Step 14: ​Connect the Jack Connector

Connect the Jack connector to the auxiliar audio-out connector on the HifiBerry soundcard. It's the 3-pin JST connector that you soldered before.

Step 15: Connect the Display

And finally, connect the ribbon's 26-pin connector to the Display's male side connector. Put attention to the orientation. The red wire should be the pin 1 that as marked in the display's PCB surface.

Step 16: ​Double-check Part's Assembling and Wiring

It's easy to make a mistake while assembling the parts or connecting the wires. Some errors can be dangerous for the electronic components (short-circuits, some specific bad-wiring combinations) so it's better to be sure that everything is correctly assembled and connected.

Put special attention to ribbon bus connection and verify that red wire is on pin 1 for every connector. Also put attention to audio jack connectors and check that they are correctly connected to the Hifiberry soundcard.

Step 17: First Boot

When you are sure that everything is in its place, it's time to boot the machine, so:

  1. Insert the SD-card with the zynthian image ready to run. If you don't have one yet, read this. You can insert the SD-card through the "window" on the bottom-side of the case. Also, if the case is still open, you can do it from the top.
  2. Plug the mini-usb power connector. A good 5V micro-usb charger is recommended (> 2 Amp).

These are the stages that you should see while booting:

  1. After 5-10 seconds, it will show the Zynthian splash screen
  2. After 3-4 seconds, it will go black
  3. If you are using a fresh zynthian image and it's the first boot, the stages 1 and 2 will be repeated
  4. After 5-10 seconds, the zynthian UI will be shown

If you get the Zynthian UI, congratulations!!! You are really close to get it!!

If you don't get an error screen or a blank screen, bad luck! Probably you made some mistake during the mounting process. You have to locate and solve the problem(s).

If you are using the Aruk RC-3 SD image (you should!), you will note that the controllers are not working at all. This SD image is pre-configured for working with the kit v2, so you need to configure the software for working with the kit v3. The simplest way of doing it is using the webconf tool:

  • Connect your zynthian to your local network using an ethernet cable (RJ-45).
  • From your web browser, access the zynthian's webconf tool by typing "zynthian.local" in the address bar. If this doesn't work for you, you should try with the IP. You can get the IP of your zynthian by navigating to the Admin Menu and clicking "Network Info". You should do that by using the "touch" interface: Click the top bar with a stick (or your nail, if it's not too wide) until you are in the Admin Menu. Once you are there, go down and click "Network Info".
  • Type the password (raspberry) for login into the webconf tool.
  • Once you are logged in, you have to access Hardware->Kit and select "Kit V3".
  • Save the changes and reboot your Zynthian.

Step 18: Testing Your Zynthian Box

Step 19: References

You will find all the building steps in