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
 ● Built in Preset browser
 ● Section locking
 ● Midi learn


Download demo version:
Demo restrictions: Preset saving is disabled. Noise 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


  • Sunset
    Jun 25, 2018

    nice vst but so much small for 4k resolution
    need resize system like spire and sylenth1

  • Fantastic Synth 🙂 Very personal sound and high quality presets. Very simple to program thanks to an immediate interface. I hope to find a wavetable oscillator in a future update

  • Maxim S.
    Jul 11, 2018

    Hi Adam, can I install the plug-in on the computer and laptop with one purchase?

    • Adam Szabo
      Jul 11, 2018

      Hi Maxim, yes its no problem as long as they are your computers!

  • Chronic Distortion
    Jul 16, 2018

    Great plugin.
    But I hope in a future update that the loading time will be shortend for now i have to wait 10-15 sec for each viper to be loaded in (FL20). But for the rest it sounds awesome delay is one of the best i ever heard even better the the virus ti in my opinion.

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Jul 19, 2018

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