Space Brain Circuits DarkSky-4, stereophonic desktop analog poly Synthesizer

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Space Brain Circuits DarkSky-4 is a new stereophonic desktop analog poly Synthesizer with four voices, dual filter, and more. 

In 2022 I reported on the small US-based developer Space Brain Circuits: its product, the MidiVolts Desktop, a polyphonic MIDI to CV interface, or the Poly Sequencer, two handy and portable devices for little money.

For the last few months, he has been working on his first Synthesizer. Today, he introduces the DarkSky-4 Synthesizer. It’s analog, polyphonic, and affordable.

Space Brain Circuits Darksky-4

Space Brain Circuits DarkSky-4

DarkSky-4 is Space Brain Circuits’ first instrument. It’s a 4-voice stereophonic analog Synthesizer consisting of four independent oscillators. They offer monophonic, paraphonic, and polyphonic play modes.

The oscillator section has mixable waveforms with a sawtooth and square wave. The latter can be gradually adjusted from a square to a narrow pulse-width waveform. It also includes a detune knob and frequency modulation (FM) either with the LFO or envelope.

Then, the signal flows into two 24dB lowpass filters with dedicated controls for cutoff and resonance. Why two filters? The developer wants to make more stereo effects possible with this configuration.  Only lowpass is somewhat limited, and a highpass option would have been good. For each filter, you get dedicated switchable attenuators or attenuverters for the LFO and envelope mod amount. There are also filter A and B volume knobs.

Modulation side, each oscillator features a dedicated VCA and ADSR envelope, allowing for better musicality and the ability to sound each note as it is pressed, says the developer. A bi-wave (sine/pulse) LFO is also onboard routable to the PW, frequency mod, and filter.

If that’s not enough, you can use the built-in patch bay for deeper modulation fun. You get:

  • 4 pitch CV ins
  • 2 cutoff CV ins
  • oscillator 3+4 sync in
  • attenuverter
  • LFO out with sync in
  • envelope out
  • oscillator 1 pitch cv out, square out, and gate out

Space Brain Circuits says the unit was designed to create a more expansive soundscape for studio and performance settings. Especially sounds that are at home in the stereo field. No presets but a polyphonic engine that can be operated like a classic mono synth.

Space Brain Circuits Darksky-4


On the back, you get a stereo output on two 6.3mm jacks (main + out where the main is also the phones socket, a MIDI IN on DIN 5 socket, MIDI out on minijack, audio input, a USB-Mini B for firmware updates, fine-tuning knob, and a power supply input.

Why the developer didn’t use a USB-C is a mystery to me. Mini USB B is an ancient connector, but thank goodness it’s not a mini USB port.

First Impression

A nice boutique analog poly synth. I find the idea of two filters exciting here so you can achieve different stereophonic sounds. Regarding the features, it doesn’t offer a supercharged setup. But it’s very hands-on and direct. I like the character of it. I am looking forward to hearing more about it.

Space Brain Circuits DarkSky-4 is available now for 666,35€ on the official Etsy store. It does not come with a power supply (12V 1000mA DC)

More information here: Etsy

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