Meet the M0SS 101 Synthesizer by Andrew John March

M0SS 101 DEMO video upload by Andrew March

"A quick demonstration on how to build a patch with the M0SS-101 synthesizer."

From the creator of WVR, the the M0SS 101 virtual analog monosynth is currently seeking funding on Kickstarter.

"M0SS-101 is a virtual analog monosynth built for a pure, hands-on subtractive synthesis, packed into a compact, rugged guitar pedal enclosure.

With 26 buttons and a single encoder, M0SS-101 gives you intuitive access to a deep 42-parameter virtual analog synthesis engine. Press a button to select a parameter, turn the encoder to modify it, and monitor your signal flow via the LED system.

Using a MIDI controller, you can map any parameter via simple MIDI learn, making it easy to integrate into your setup. Up to 17 presets can be saved and recalled for quick access to your favourite sounds.

The 26 RGB LEDs use colour and brightness to represent signal flow, modulation paths, settings and selections. A separate row of 11 LEDs at the bottom gives you instant visual feedback on the currently selected parameter. I aim to offer an affordable, compact, and versatile instrument, without sacrificing features, ergonomics, or most importantly, fun. I hope you'll enjoy playing this synth as much as I have :'-)"

MODULES

OSCILLATORS

2 Oscillators
Stackable square or sawtooth waveform
3 octave options
Pulse width for each oscillator
Detune on oscillator 2
Transpose, pitch-bend and fine-tune
10 octave pitch range


FILTERS

High-pass - based on Moog ladder filter
Low-pass - based on Korg 35 filter
Band-pass - based on Oberheim filter
Cutoff and resonance parameters
Key-tracking can be toggled on and off

LFOS

Triangle, square, or random waveforms
Random waveform is S&H on the white noise generator
Frequency range is 0.1Hz to 10kHz
Low and high range toggle
Low mode is 0.1Hz to 20Hz for normal modulation
High mode is 20Hz to 10kHz for FM

ENVELOPES

1 millisecond to 20 seconds range for attack, decay, and release
Can be triggered by the square wave of the LFO, by MIDI note on/off events, or by clicking the encoder
Continuous slope control from logarithmic to exponential

NOISE
White or Pink noise

XOR

Based on a Logical Exclusive OR circuit
Can create tones similar to a ring modulator
Always sourced from the square waves of the 2 oscillators

MIXER

Has inputs from oscillators 1 and 2, plus the noise generator and XOR module
Like every parameter on M0SS-101, each channel can be dynamically controlled by MIDI CC

GLIDE

Configurable speed. Very slow, very fast, or anywhere in between

DELAY
Wet/dry, delay time and feedback controls
20ms to 185ms delay line
At the fastest settings it can sound like a basic reverb
At the slowest settings it can have a slap-back effect

VCA
Master volume control
Control signals from LFO and ADSR
Features a special Drone mode, where the envelope generator fractionally attenuates the output, essentially inverting the ADSR logic

MODULATION
9 signal paths to design the modulation signal flow, which can be individually attenuated
These paths are all multiplexed, so each source can be connected to all of its destinations at once, each with its own attenuation
The modulation paths are:
LFO -> VCA
LFO -> Filter cutoff frequency
LFO -> Oscillator 1 pitch
LFO -> Oscillator 1 pulse width
LFO (square wave) -> ADSR trigger
ADSR -> VCA
ADSR -> Filter cutoff frequency
ADSR -> Oscillator 1 pitch
ADSR -> Oscillator 1 pulse width

MIDI
USB MIDI Host - Powers any connected USB MIDI compliant controller
TRS MIDI in and thru - TRS Type-1 MIDI standard
MIDI Learn - Select any parameter on the M0SS-101, then send any CC to map that CC to the selected parameter
The CC mapping is saved on a per-preset basis, so each preset can have a unique CC to parameter map
MIDI pitch-bend commands are respected, and the pitch-bend range is configurable independently for up and down.
MIDI channel can be 1-16, or OMNI

MEMORY
17 memory slots
Save and Load all the parameters of the synth
Save and Load all the MIDI CV to parameter mappings
In Save and Load mode, the RGB LEDs indicate which slots are unused, and which slot is currently in use.
All the memory slots can be over-written any number of times
All the memory slots can be loaded and then saved to a new slot, to make copy

TECHNICAL

M0SS-101 runs on the Bouffalo Labs BL616 microcontroller, a low-cost RISC-V chip with an integrated Analog DAC. The DSP engine is designed in Faust, a functional DSP language. M0SS-101 is powered by a center-negative 9V DC power supply. It has a mono 1/4" audio output, a USB type-A MIDI Host connector, and 1/8" TRS type-A MIDI in and thru. It consumes 130 milliamps, plus any additional power consumed by a connected USB MIDI device.

The DIY Kit for M0SS-101 has all SMD components pre-soldered, and includes all the hardware and through-hole parts needed for the build, including the enclosure. Assembly requires only a basic skill level for soldering, and is appropriate for a beginner. You will need a soldering iron, solder, flux, and M2 and T8 drivers. You will need a computer running python to flash the firmware.

BACKGROUND

I have been an embedded engineer for 6 years, working mostly as a freelancer, and with my collective Ultra Palace. In that time I have slowly moved toward my goal of working exclusively in audio. I have worked on numerous MIDI devices, such as Midinome and Midithrone with my company Ultra Palace, and for clients and startups across the globe. I have also released WVR, an ESP32 audio development board, where I worked consistently for the last 4 years with a community of adopters to refine and expand its functionality, following a successful campaign here on Kickstarter, and eventually distributing it through Sparkfun. WVR has been featured in print editions of Make Magazine and Waveform Magazine, and online in blogs like Hackster, Matrixsynth and Synthtopia.

I have been working on M0SS-101 for a little over 2 years, and have gone through 5 hardware revisions in that time. I was initially inspired to begin the project when I first heard about the Sipeed M0S development board, and this is where the synth got its name (it stands for M0S-Synth). The Sipeed M0S is a development board for experimenting with the BL616 Microcontroller, which is based on RISC-V architecture. I was drawn to this part because of its built-in analog audio DAC. This is a very unusual peripheral for a microcontroller, and coupled with its high clock speed, DSP instruction set, FPU, and incredibly low cost, it is a remarkable target for embedded audio. I decided to pair this hardware with a fascinating open source project called Faust, which is a functional DSP language, developed by the GRAME-CNCM Research Department in Lyon, France. Faust can produce highly optimized DSP code in C, from a high level DSL. It is fun and challenging to use, and I'm not sure I could have built M0SS-101 in quite the same way without Faust, and its supportive community of talented mathematicians and developers.

In the initial phases of development I was deeply inspired by the MG-1. I love how its designers set out to create an instrument that was both powerful and cost-effective, and in that process produced something that is so very inspiring to use. MG-1 was the first synth for many musicians in its day, and I love the ethos of this history.

With M0SS-101, I hope I have found a way that I can contribute in a small way to the world of synthesis. Since its interface avoids menu diving, and instead uses buttons and light, I hope it succeeds in producing a hands-on, and inspiring experience, in a compact package. I believe that this style of interface solves some hard user-interface problems endemic to DSP synthesis, and that this opens the door to a whole domain of new experiences for synth lovers, in a low-cost package. I would love to use this same kind of interface for a sequencer, a poly-synth, an additive synth, an advanced oscillator, and many many other applications where it has historically been a challenge to accommodate deep control over a broad feature set, in a compact package, without sacrificing ergonomics and fun.

In this process I've been incredibly fortunate to have the support of a small team of dedicated synth enthusiasts who have worked tirelessly with me over these last 2 years. Together, we've iteratively tested, debugged, and refined the M0SS-101, added new features, and developed a hardware design that is both robust and cost-effective. A huge thank you for your tireless efforts to my dear friends Filip Pietruszewski, Chris Rozek and Steve Bjornson.

You can find additional details including pics of prototypes at Kickstarter here.