NoiseRoom UIO has released Andes JX, a free and open-source polyphonic subtractive synthesizer for Windows.
The independent audio lab is based in Quito, Ecuador. Last year, we featured its NoiseRverb convolution reverb, which captures the acoustics of historic churches around the city.
Andes JX continues that connection to Ecuador, but from a different angle. Its visual design is inspired by the stone, mist, sky, and high-altitude landscapes of the Ecuadorian Andes, while the 33 factory presets are named after real locations across the region.
The preset bank covers everything we’re used to in the familiar territory of subtractive synths, including basses, pads, leads, brass, keys, plucks, and effects. The preset names are pretty cool, though (Cotopaxi Acid, Cayambe 5th, Imbabura Pedal, Quilotoa Aqua, Páramo Sostenuto, etc.) and combine geography with hints about the sound.
As for the engine, the synth has two anti-aliased oscillators offering sine, saw, square, triangle, and PWM waveforms, plus a noise generator and continuous blending between the two oscillators.
You can switch between two filter models. The State Variable Filter is the default option, while the nonlinear Moog Ladder model adds saturation and a stronger resonance.
Modulation comes from independent amplitude and filter ADSR envelopes, along with a global LFO for pitch, pulse width, and filter cutoff. Andes JX also provides key tracking, filter velocity sensitivity, stereo width, mono and poly modes, and three glide settings (off, legato, and always).
The engine supports up to 16 voices of polyphony and uses 2x oversampling. I like that it’s pretty focused, rather than another synth packed with effects and an enormous modulation matrix, which also makes it easier for beginners to study.
That educational side is a big part of the project. Andes JX is written in C++ with JUCE, and its source code is available under the GNU GPLv3 license with bilingual English and Spanish documentation.
The code separates the DSP, plugin logic, and graphical interface into different layers. Technical references accompany the oscillator and filter implementations, providing students and developers with a practical path from DSP theory to a working instrument they can inspect, modify, and extend.
The JX name acknowledges the Roland JX family and the educational JX11 synthesizer, which is related to Paul Kellett’s open-source MDA JX10. NoiseRoom UIO presented Andes JX at the AES Latin American Conference 2026 in Lima as part of its work on open-source tools for teaching DSP and audio software development.
A ready-made download is currently available in VST3 format for Windows.
Download: Andes JX (FREE)
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Last Updated on August 25, 2026 by Tomislav Zlatic.
