Open Source Instruments to Watch in 2025: Pt2

When it comes to our modern synth era, it sure feels like we're living in a time of great choice and potential. Want an analogue polysynth? You got it, and at a reasonable price, too! Crazy digital stuff? Here's a boatload; software & hardware in all shapes & sizes!

The open-source arena has been an area of much excitement. Some projects have appeared that are completely open in terms of both hardware & software; build it, code it, do the whole thing! Others are pre-built, yet allow the user to code plugins or modules that run within. Following on from part one, let's take a look at some more devices:

Percussa XMX

Pre-built / $499 https://www.percussa.com/

The XMX is a smaller sibling to 2019's SSP - an imposing and powerful virtual modular system. At roughly 25% of the SSP's original price, the XMX packs much of the power & sonic footprint of it's larger sibling into a 28HP panel.

The XMX ships with all the basic modules you need to create a synth voice, missing out only on the SSP's 3D-scanning oscillator. There's a flexible VCO/LFO, 3D wavetable VCO, physically modelled membrane, waveshaper, granular processor, powerful filters and a whole lot more.

But the device can also run 3rd-party/user plugins and coding whizz TheTechnobear has taken it upon himself to create not only new modules (including Mutable Instruments ports), but an alternative operating system! The only catch with one-man shows I guess, is that progress can take a while. Many of these features, like ports of Clouds, Plaits, Marbles & Rings were announced for the XMX a number of months ago, yet they're unavailable - despite seeming in a state of near-completion. You can follow development here.

SHMØERGH Hog

Experimental Project / £??? https://www.shmoergh.com/hog-guide/

SHMØERGH, which apparently "doesn't mean anything but sounds like a Nordic design firm" have released Hog; a non-commercial, open source instrument with an advanced-level build. It's analogue, features two voices of the usual waveshapes, plus a sub oscillator and noise.

Personally, it's the "playground" section that appeals most - the player may choose a cross-modulation routing from the following:

1. Hard sync: Resets the frequency of VCO2 to the frequency of VCO1. At the same time it modulates the pitch of VCO2 via LFO2. Experiment with detuning VCO2 using the detune knob or the VCO2 octaves as well as with the speed and amount of LFO2.
2. FM: Modulates the pitch of VCO1 with the output of VCO2. Play around with the frequency, octave and the waveshape of VCO2. You can even turn off VCO2, the modulation remains on.
3. Filter cutoff AM: Modulates the filter cutoff with the output of VCO2. Try switching VCO2 to the lowest octave and play around with detuning it.
4. VCA (ring) mod: Modulates the control voltage of VCA with the output of VCO2. Again, experiment with various octaves and detuning of VCO2.

I like the spirit of wild experimentation, flexibility and also the aesthetics of this one - so it's a shame that I can't solder for the life of me!

Synthux Academy Touch 2

DIY €139 / Pre-built €239 https://www.synthux.academy/simple-synth/touch2

The Touch 2 is based upon the popular Daisy Seed platform. This microcontroller features 96kHz / 24-bit audio hardware, an ARM Cortex-M7 MCU running at 480MHz and 64MB of SDRAM (for up to 10 minutes of audio buffers.) For this instrument, Synthux have created a touch interface with swappable faceplates - each paired with a different flavour of firmware:

touch string - Plunk and bang on metal, plastic and wood. Add distortion and modulation

touch looper - Sample, loop, mix, stretch and manipulate recordings in real time

touch fx - Process your guitar, voice or synth with  wobbly delay, chorus, reverb and various distortions

touch bass - Play thick basses, leads and pads, mess around with AM and a generative melody maker

The company also offers a discount for those who run synth design workshops.

Zynthian

Some Assembly Required / €360 - 452 (exc VAT) https://shop.zynthian.org/

Finally, I'd like to mention Zynthian, the Pi5-based Linux groovebox. I covered this instrument recently and 2025 is set to bring a flurry of development to the platform. A new operating system, Vangelis, promises context-based help, a snazzy envelope display and a number of other features - additionally, there's the promise of JUCE.

JUCE is a coding playground for building programs, plugins, etc. It's cross-platform - write your plugin and export to whatever format; Win, Mac, JUCE doesn't care. Amongst these options, Zynthian's Linux LV2 format!

JUCE therefore really opens things up, even introducing the promise of DSP56300-based emulations to the platform. Osirus and OsTIrus (Access Virus emulations) are already running on Zynthian, though some more tweaking is required.

It's obvious that 2025 will be an exciting year for open source instruments. Did we miss something great? Let us know and we'll be happy to cover it!

Posted by MagicalSynthAdventure an expert in synthesis technology from last Century and Amiga enthusiast.

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