Viper aims to deliver the sound characteristics of legendary hardware synthesizers in a virtual format. We can call Viper a Virtual Performance synth, with a vast array of features like: multiple oscillator types with user waveforms, Sync, Frequency Modulation, Ring Modulation, unison up to 8 voices, filter saturation, filter routings, mod matrix, high quality effects, a powerful arpeggiator, and much more!

A lot of time and research has been invested to make the sound engine of Viper capable of delivering a wide array of sounds, everything from smooth, lush pads, huge basses, and powerful leads, typically associated with traditional analog synthesizers. This was achieved with careful coding, experimenting, analysing hardware synths, and using the ear to fine tune the controls. A constant randomization is also active in the synth to slightly alter its sound to mimic electronic components.

The engine is written in optimised code to use as little CPU consumption as possible, while maintaining a high quality sound engine, finding a good balance between the two. The synth automatically turns off any parts that are not used to further reduce CPU usage. Viper also has a smoothing algorithm for its controls to remove the ‘steppyness’ when it goes between values to give that extra polished sound.

Key features:
● Classic Oscillators with user waveforms
● Multisaw (up to 9x Sawtooth waveform)
● Sub Oscillator
● Noise with coloring
● Punch
● Osc Sync, FM, RM
● Unison up to 8 voices
● 2 Zero Delay Feedback filters with Low Pass, High Pass, Band Pass, Band Reject (notch)
● Filter Saturation curves
● 4 Filter routings: Serial 4, Serial 6, Parallel, Split
● 4 Envelopes: Filter Env, Amp Env, Mod 3 and Mod 4
● 3 LFOs with Oscillator shape morphing
● Mod Matrix
● FX:
● Character (analog boost)
● Distortion
● Filter effects: Ring Modulator, Frequency Shifter, Vowel Filter, Comb Filter
● Phaser
● Chorus
● Delay
● Reverb
● Equalizer
● Arpeggiator with user patterns and Midi Out
● Built in Preset browser
● Section locking
● Midi learn
● Resizable GUI


Download demo version:
Demo restrictions: Preset saving is disabled, silence every 60 seconds. (Because of the demo limitations, automation is not available in some hosts, but is fully functional in the retail version)
Requirements: Win 32/64 compatible system with SSE2 (or higher).

User Manual:
The user manual for Viper can be downloaded from here: Viper Manual.pdf

This is a 32 & 64-bit VST for Windows only! All future updates are free!
Please evaluate the demo thoroughly before purchasing!

Why no Mac version?
Unfortunately, FlowStone does not yet support export to AU, Mac VST yet. As soon as FlowStone supports this, the synth will be available in this format.

Free Soundbanks:
Daniel Craighead Trance Access for Viper Vol.1.zip


  • Joerg Lamster
    Jan 13, 2018

    I will wait for the 64bit version…. 32bit is technology of the last decade. And I don’t want to bridge 32bit plugins any longer

  • Locke
    Jan 15, 2018

    32 bit and no Mac OS version???!!!! ???

  • Cristiano Leitão
    Jan 22, 2018

    i need this for mac 🙁

  • Reinis
    Jan 25, 2018

    Anxiously awaiting the 64-bit version!

  • Carl Crellin
    Jan 28, 2018

    Waiting for 64-bit version !!! hurry lol

  • Michael O'Neal
    Jan 30, 2018

    I’m really looking foreword to the 64 bit version release.

  • Vagelis
    Jan 31, 2018

    Thanks!Would be amazing also if you could release seperate the step sequencer as midi fx !!

  • Expert Mode
    Jan 31, 2018

    Needs a 64-bit, bug fixes, low cpu (average) and more features also with the 32-bit

  • fab
    Feb 02, 2018

    As soon as there is a 64 bits version for windows, i’m in. No questions asked. I got already fucked up by Refx with vanguard 2.0 that never came out so i don’t want to feel it up my a.. again…you know what i mean 😉

  • yabiss
    Feb 02, 2018

    64 bits please for Viper AND JP6K !

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