Tag: diy




here we are ….

We both decided to meet each other here.

Somewhere in between time, space & room.

As you´re accepting the challenge to assemble SPROOM i´m trying to give you everything you need for a successful ride.

For SMT projects i´m not giving step by step based instructions like for THT as my commercial versions come assembled with the most common parts.

Don´t worry! The DIY version is proven to be working 😉 (Props to My_Modular_Journey)

BOM overview:

Need to know

  • Depending if you´re a baker, heat plater, hot flower or poor iron man, you should consider a further step based assembly!
  • The mainboard is the only PCB with SMT parts on both sides. (FV1 chip) so you can possibly run into some reflowing issues, depending on your technique. Therefore i´m advicing to attach the FV1 chip at least and in best case just with an iron.

HINT: i´m using hot air technique and nether managed to reflow parts on the backside 😉

  • The LED´s of the control pots are very bright if using clear super bright LEDs. Due to a mystery it´s not possible to drop the brightness with changing resistor values. In this case i´m advicing to use common diffused ones with lower brightness.
  • For C1 & C2 i´m highly advicing to use C0G caps as they´re a sensitive part at the incoming audio path.
  • Regulators you should go for this one or similar.

EEPROM programming

All right, your SPROOM is already working with the internal 8 algorithms.

Now let´s figure out how to program the EEPROMs.

There are several methods to flash em. I´ve chosen an Arduino Uno as EEPROM burner.

You can use the already prepared codes for both ROMs or create own sets of algorithms with the SpinASM assembler.

What you need:

  • Arduino Uno (possibly anyone instead of Nano)
  • Arduino IDE and basic understanding on how to upload codes
  • Breadboard or the “NoisyFruits Arduino UNO programming HAT ISP_2432_OLED”

The Process

You can use the already prepared codes for ROM1 & ROM2, or dive deeper into creating own sets of algorithms.

Here´s how you wire up the chip with the Arduino. You can also use the 5V source for this …

With the SpinASM Assembler you can create or modify algorithms (the super nerdy way) or you can create custom sets of existing algos (the not so but still nerdy way).

It´s about exporting the set of algos into a hex file / code and importing / exchanging it into the ROM.h from the Arduino code.

Make sure you set the output directory where you want the file to be exported. You just need the source file.

Open the source file with a simple text editor and you will see blocks of cryptic hex codes.

Each of these blocks stands for one algorithm. If you get the text formatting and the file name correct with outputting it out of SpinASM you could simply copy the whole text. BUT i´ve never figured out how to format the source file to simply copy & paste it.

That´s why you need to copy & paste the 8 blocks of hex code by hand without that prefixing:

const unsigned char ROM_00[] PROGMEM = {

Do a compile check if the IDE likes what you´ve done and simply upload that code to your Arduino.

Now the Arduino flashes the EEPROM on each repowering, even without the IDE.

With checking the serial monitor @9600 Baud you will see this:

YOUR EEPROM is flashed and ready to go 🙂

If not take a banana and check your head.

If you figure out how to make the process of flashing EEPROMs easier let us know!

Manual Latching Switches DIY Guide

Manual Latching Switches DIY Guide


  • Thonkiconns (Mono or Stereo) Yes, it can handle stereo signals, the DIYers easter egg 😉
  • DPDT Switches 7x7mm –> ALI, Ebay
  • Caps 6mm outside / 3,3mm inside –> ALI , works with rectangle or round holes 😉

The assembly is pretty self explaing if you know how to place the buttons :p

The orientation matters!!! Take a look onto the side parts of em, the side with two holes -> II <- shows to you, or the bottom of the PCB.

As the button holes of the panel are very precise i´m advicing to solder the buttons at last with mounted panel. So you can make sure they glide softly.

1U instruction

You will quickly realize something´s different here this time …

The thonkiconns share their ground pins and this makes em sit very tight and uncool.

To make sure they sit where they should, place em all as good as possible, solder the middle pin of each, put on the panel or better to say squeeze on the panel and reheat the soldered pins. This will force em to get the right position. I´m sure you will get the myth behind 😉

Happy switching 🙂

Dual VCA DIY Guide

Dual VCA DIY Guide

The updated version 1.3 got trim pots now for adjusting the initial level / closing of the VCAs.

As well the LEDs get driven by transistors now.

Else nothing changed.

BOM Rev. 1.2

BOM Rev. 1.3

All pots are linear “B”



At first i´m advicing to start assembling when you got all the parts and tools you need and of course i´m assuming you got all the skillz you need for soldering and desoldering! Following the documentation you will see which parts i´ve been using. In almost every case i´m using common parts you can easily find out there.

Step 1 – Resistors

Follow the BOM and designators “R” on the PCB and put the correct R to its footprint. You see, the resistors are vertical alligned to safe space. The orientation doesn´t matter. Take care for R10, R16, R18 & R19! They´re in ohm.

Step 2 – Capacitors

You got 2 Values of those yellow ceramic caps (1nF and 100nF), the designator on the PCB is “C”. At first choose the 1N caps, the rest is 100N. Orientation doesn´t matter.

Step 3 – Transistors

In best case these 2N3906 PNP transistors should be matched. I´ve been widening the pad distance a bit, but take care! The pads are very close to each other. Take a deep breath, respect the orientation and make them sit tight.

Step 4 – IC Sockets

Sure, you can solder the ICs directly onto the PCB, but i´m not advicing to!

Little trick, attach the sockets with some sticky tape, at first just solder one pin. Make sure it sits tight and plane on the PCB. In case you disrespected the orientation, don´t worry!

That´s why sockets safe your life 😉

Step 5 – Diodes

You got only two diodes to mount. RESPECT THE ORIENTATION!!!!

Step 6 – Electrolytic Capacitors

Two 47uf caps. You can choose 10uf aswell or something in between. Make sure they´re capaple of at least 25V. The rule says twice the voltage you feed. In case you do something wrong here one of the caps will blow up or explode.

RESPECT THE ORIENTATION!!! Round hole minus leg.

Step 7 – Eurorack Power Pin Header

That guy is attached on the other side of the PCB!!!! The 3 inner pins are ground and connected to the ground plane which is all over the PCB on top and bottom. You may will experience ground related pins to be a bit harder to solder. That´s because these pads cool down very quickly due to its thermal connections. Especially for the pin header i´m advicing to make the iron hotter. You see on my “beautiful” solder spots the iron was already a bit too hot.

Step 8 – Thonkiconns

Yes, it´s time! Now we come over to the funny parts. The thonkies have 3 pins. You can´t place them wrong but make sure they sit tight and plane on the PCB, otherwise you will have a hard time attaching the panel. First solder the middle pin, check if it´s placed well, solder the other pins.

Step 9 – Potentiometers

The pots should snap in and sit tight and plane on the PCB! Again, solder one pin, check its placement and solder the other legs.

The two Alpha pots must be 100k, but can be linear or logarithmic. A question of taste … The Song Huei pots can be something between 10k-100k. They simply attenuate the incoming CV signal, while the level pots give a specific current and can´t be changed! I´m advicing to choose the values i´ve been using or you dive into the simulator to calculate the right balance (again).

Step 10 – ICs & LEDs

Place the ICs to their sockets and make sure you respect the orientation. You see, i´ve already placed the TL072 wrong verse 😀 The mark on the PCB corresponds to the mark on the IC.

In case you want to know what happened to the TL072 after powering 😀 :

Place the LEDs to its place but don´t solder them yet! They need to be adjusted with the panel. The orientation matters! Long leg round hole. You can choose your desired color but choose bright ones. More mcd means more brightness.

Step 11 – Panel Mounting & LED soldering

So, here we are. Placing the panel should be easy in case all the parts sit where they should!

In case you don´t have the right tools to mount the nuts use some pliers BUT be careful not to scratch the panel! At first just mount two nuts to make sure the panel is placed well, than solder the LEDs. Make sure they correspond to the indicator graphics ….

I´m using an old tooth brush to clean the PCB at least.

Step 12 – Quick Check

Check all your solder spots, reheat the critical ones. Check the power pins of the pin header with a multimeter to make sure there is no short!

You´re done


VCA not closing correctly.

This happens when the chosen parts fall out of the tolerance range too far. The calculations i´ve done are very theoretical and based on mathematical optimums. The real outta world isn´t that precise. In most cases this is caused by the transistors or the resistors R31 & R32. Swap the resistors to 1M and you should be safe 😉