After getting some interest in synthesizers, I soon wanted to design my own. I fall upon famous projects like musicfromouterspace or the lmn3 and a new project launched by the Synthux Academy called the Simple which caught my curiosity.
The idea behind Simple is to have a board whose layout let you put potentiometers, audio jacks and switches where you want on a grid of footprint and connect those components to headers where you can fit a microcontroller.
I liked the idea so much that I pressed buy as soon as possible. The kit arrived and it is composed of:
A daisy-seed (microcontroller board designed for audio)
A few potentiometers, switches, and jacks
Few cables
The Simple PCB
The first picture shows the “raw” synth with its Simple PCB and components soldered and wired.
With the kit in my hand, I directly start to build my own synthesizer. My goal was to make an open-source synthesizer, easy to understand and replicate for beginners.
The daisy seed is such a great choice to reach that goal. It is an amazing product to make synth with and gives the possibly to program it in C++, Arduino, Max/MSP gen~ or Pure Data. I decided to make the code using Arduino to make it easier to understand and replicate for beginners.
The final result is an east-coast-inspired synthesizer with two effects: a decimator and a wavefolder that can easily degrade the sound and make it dirty (it’s My-Dirty-Syth after all, the name originally came from a typo of My-Dirty-Synth and was kept like that because why not).
The synth has MIDI capabilities. It listens to all channels and reacts to note On, note Off, pitch bend, and control change. The control change affects the filter cutoff frequency.
The design starts with an oscillator whose shape can be chosen between sinus, triangle, sawtooth, and square. In addition to the main frequency, it is possible to have the 1st and 2nd octaves mixed with the main oscillator.
The signal is then sent to the two effects: wavefolder & decimator
Both effects have a potentiometer to drive their strength. It is also possible to combine the two effects differently with a 3 positions switch.
The next module is the filter. You can change the filter resonance, cutoff frequency, and drive. With two switches you can change from no filter, high pass filter, low pass filter, or bandpass filter.
Finally, you can find the signal can pass through a VCA or lowpass gate with attack decay and release adjustable. You can either activate the VCA/LPG with the VCA Mode switch and then select what kind of system you want your signal to pass through VCA and/or LPG.
The design of the simple kit makes it eurorack compatible with a size of 42HP. The final design was put in a PLUS case by FrapTools.
The front panel is a two-sided PCB made by PCBWay. The top consists of just the custom design and the bottom contains components to make the synth MIDI-compatible. I made a window in the front panel to see the nice Simple Synth circuit board.
Everything is open source (source code and front panel PCB) and can be found on GitHub here: github.com/lucblender/My-Dirty-Synth
