FKFX Audio Opus 55 is a new Synthesizer plugin that uses chorophonic synthesis, a unique technique where many monophonic voices play together.
Monophonic, polyphonic, and paraphonic are common terms in the Synthesizer world. For example, the small Behringer Mini synths are paraphonic because they have multiple voices that are routed through a single filter and a VCA. But what is chorophonic?
The French developers of FXFK Audio (one ex-Ohmforce coder) have released OPUS 55, a Synthesizer that uses chorophonic synthesis that offers a different way to arrange voices.
FKFX Audio Opus 55
With monophonic voices, only one voice can be played at a time; with polyphonic voices, several can be played. In chorophonic synthesis, many monophonic voices play together. This is not the polyphonic way where you stack copies of the same sound.
Here, the synth creates an ensemble of voices, each with its own independent settings, including pitch curve, tone, and movement. Play a single note on Opus 55, and you get wide unison, lush chords, and living textures, say the FKFX Audio developers.
On the left side, you have the chorophonic oscillator powered by a new Union-X engine where the pitch, spread, tone, and motion parameters of the oscillator ensemble evolve through morphable curves. These turn a single note into a wide multi-voice sound.
Part of the engine are also various selectable wavetables, oscillator effects (FM…), and a morphable waveshaper with hundreds of shapes. They cover a wide range and respond to your dynamics in real time.
To add weight and pressure to your sounds, it also includes two independent sub-oscillators.
From here, the signal enters a multimode filter with various types (low-pass, high-pass…) modeled after vintage synth circuits. They are fully tweakable with classic controls like cutoff, resonance, and more.
More Shaping & Movement
Right after the filter section, there is another shaping stage called mod fx. Here, you can find a wide range of sound modifiers, including a notch cascade filter, flux modulation, oscillator mod, frequency shifter, vowel filter, and flanger
The FKFX Audio Opus 55 also offers quite a bit in terms of modulation. The classic one is the envelope that has an ADSR characteristic. This can also be modulated by the LFO and LFE. Yes, there are two different modulators.
LFO is a low-frequency generator that allows you to create complex, non-repeating LFO shapes in seconds in the dedicated LFOGrid. MIDI grooves can also be imported. You can sync it, control the rate, and it has morphing capabilities.
On the other side is the LFE, which is a low-frequency envelope. It’s a hybrid envelope, halfway between a traditional LFO and a classic envelope. It can modulate a parameter in an interesting way.
The first half of the LFE acts like a conventional envelope, while the second half can loop continuously, like an LFO, giving you interesting movements.
Another unique feature of Opus 55 is its Kick sync functionality. Import your kick render, then visually align your sub-bass phase right in the synth. This saves time and eliminates the need for later alignment.
Further, you have a multi-FX section with a retro-flavored 80s-style reverb with freeze and an analog diode-clipping-based distortion unit.
First Impression
At first glance, an intriguing, very bass-heavy Synthesizer plugin with a different concept. The released sound demo offers a first glimpse at the sonic spectrum.
The Opus 55 becomes particularly interesting when modulation comes into play. This, as is well known, is FKFX Audio’s forte. An interesting release, but I’m still unsure whether it brings that much new content.
FKFX Audio Opus 55 is available now as an exclusive Patreon supporter release. New supporters can get it through the $25 Patreon tier until August 17th, 2026. The official public release will be in September with a price tag of $89.
It runs as a VST, VST3, and AU plugin on macOS (native Apple Silicon + Intel), and Windows.
More information here: FXFX Audio
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