Unstable from Morphoice is a free polyphonic synthesizer inspired by the legendary Yamaha CS-80 analogue synthesizer.
The developer, Morphoice, describes Unstable as “in no way intended to be a CS-80 emulator, but still probably closer to the real hardware than anything out there”.
In recent weeks, unstable is the second classic Yamaha-inspired synth after BaconPaul’s TX81Z-inspired FM synth plugin – Six Sines.
Emulation or not, anything remotely close to the CS80 must be good news.
Unstable is a modern take on the CS-80, closely modelling the original hardware in some areas and offering new flexibility in others.
The poly synth has two synthesis layers, each featuring a noise, sawtooth, and pulse wave oscillator with adjustable Pulse Width and variable speed pulse with modulation.
Although the waveforms are closely modelled on the classic hardware, Unstable provides a more flexible blending of layers by allowing you to adjust the level of each oscillator independently.
The filter section also deviates slightly from the CS-80 design.
In this case, we have an authentic CS-80-style high-pass filter, but the low-pass is a self-oscillating, Moog-style ladder filter.
The Moog-style filter brings a different character to the CS-80-inspired sound; you get that smooth, thick texture you expect from a Moog synth and rich harmonics that bring dull sounds to life.
The Ring Modulator is one area where Morphoice has gone all-out to recreate the magic of the CS-80. The CS-80 ring modulator gave some iconic soundtracks, including the original Doctor Who, their unique sound.
Unstable’s Ring Modulator has an analogue-style Attack and Delay envelope modifying the modulation speed.
You even get a virtual ribbon controller to bend the pitch up to one octave. The CS-80 ribbon controller often divides opinion: some think it provides ultimate expression, and others consider it a needless addition.
Whatever you think, it’s part of the CS-80 character, and it’s nice to see it represented here.
Unstable has a sixteen-step arpeggiator; while it’s functioning, some options aren’t yet implemented at this early beta stage.
Unstable utilizes the effect engines from some of the most popular Morphoice plugins, DarkStar Reverb and Delay, and WingMen Chorus.
It’s early days, and Unstable will undoubtedly have a few issues to iron out, but it has great potential! It’s free while in beta, but I’m unsure if a new pricing structure will come later.
The developer suggests rendering your audio on critical projects while the plugin is still in its beta state.
If you enjoy Unstable and fancy buying the developer a beer, you can do so via PayPal (email on the plugin page).
Unstable is available in AU and VST3 formats for macOS (13.6 and higher) and Windows (10 or 11).
Download: Unstable (FREE)
More:
- BaconPaul releases Six Sines, an Open-Source TX81Z-inspired FM synth plugin
- Full Bucket Music releases Paralogy, a FREE Crumar Trilogy and Stratus emulation
- Free Synthesizer VST Plugins
Last Updated on February 4, 2025 by Tomislav Zlatic.
