Superbooth 24: Befaco Oneiroi, new experimental digital synth voice

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Superbooth 24: Befaco Oneiroi is a new experimental, wild digital synth voice packed with rich oscillators, looping, filters, resonators, and more.

Last year at Superbooth 23, the Barcelona-based company Befaco delighted us with the characterful, dirty FX Boy effects module, which allows you to insert Gameboy cartridges. A highlight was that they worked with numerous Eurorack developer friends. 

This year, they don’t make it any less experimental and will. Befaco has just announced the Oneiroi experimental synth voice.

Befaco Oneiroi

Befaco Oneiroi

Oneiroi is a new live performance-oriented experimental digital synth voice for Eurorack. It is powered by the latest revision (mk3) of the mighty Rebel Technology OWL programmable DSP platform, which features 24-bit 48 kHz stereo audio and 32-bit internal processing.

It is a module with many knobs and sliders that allow hands-on control over the parameters. A newly developed digital engine with a colorful mix of synthesis and sampling works underneath them. 

The Befaco Oneiroi’s sound generator consists of two distinct oscillators. First, it has a stereo supersaw oscillator with detune control inspired by the iconic Roland JP-8000. It’s perfect for extensive, sharp sounds.  

Then, it hosts a 2048-sample dynamic wavetable oscillator with offset control. A sine oscillator supports both oscillators.

On the sampling side, it also features a 5-second looper with continuous speed control (2x reverse to 2x forward) with pre- and post-looping selectors. You record external signals via the external stereo input or the module’s output.  Excitingly, its buffer also feeds the aliasing wavetable oscillator.

All three oscillators have only a single V/oct input and an additional unison control.

Befaco Oneiroi

Colorful Effects

Befaco says Oneiroi is suitable for ambient pads and drone-like soundscapes. Effects are needed for these, especially to make them bigger and more spacious. Don’t worry; Befaco made sure to do that.

It starts with a stereo filter with four flavors: lowpass, bandpass, highpass, and comb filter. The filter can be freely positioned along the effects chain, making it a very versatile tool.

Next to this, you have a 3-band resonator with tune and feedback controls.  Resonators are very underrated effects, and I’m curious what impact they will have on the final sound. There is also a built-in 2-tap echo with controls over time and density to add more room. 

For the final touch, Oneiroi also hosts a reverb with macro control for the size, filtering, and direction. It is a synth voice module for Eurorack, and modular synthesizers stand for extensive modulation capabilities. Yes, Befaco’s new module also took care of that.



The engine offers a built-in LFO that ships with various types of self-modulation with configurable routing. It has multiple waves and controls over the level and speed.

Additionally, you can work with a powerful randomizer with four different targets, three intensity levels, and handy undo/redo. Clever, there is a soft take-over functionality for showing where the values are about the position of the control, mainly after the randomization process.

If that’s not enough, Befaco Oneiroi has eight CV inputs for the main parameters, and four can also be assigned to secondary functions. External sync via the sync input (up to 300 BPM) is also onboard.

On the connection side, it has a stereo output and input. The latter has three switchable gain levels and a two-colored LED for monitoring.

Befaco Oneiroi First Impression

As a fan of drone synths and ambient sounds, I am greatly interested in the Befaco Oneiroi module. It awakens my inner drone passion. The combination of various oscillators, looping, and effects is lovely. It’s a very tempting module. 

Befaco Oneiroi will be available in early Summer 2024 for an estimated price of 400€+ TAX (around 475€ final price) for the assembled unit. Befaco will have a booth (Z170) at Superbooth 24 this week.

More information here: Befaco

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