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


  • Johan
    Aug 03, 2019

    Can I register anywere to get a heads up when the sale is comming?

    Regards J

    • Adam Szabo
      Aug 03, 2019

      You can sign up to the newsletter and get info about it when it happens

      • Will Wong
        Aug 04, 2019

        Hi Adam,

        Is the sale coming soon? Any estimated date?


        • Adam Szabo
          Aug 04, 2019

          I will have a sale when I have designed my new website, but I think that will happen in autumn sometime

      • Johan
        Aug 05, 2019

        Thanks Adam, I will!

      • roni amar
        Sep 22, 2019

        hey adam when there will be a sale? i love the synth and love the virus ti but i cant afford it at this price

        • Adam Szabo
          Sep 22, 2019

          Hopefully christmas time

  • Daanish Matheen
    Aug 07, 2019

    How many license?

    • Adam Szabo
      Aug 08, 2019

      One per person

  • VijayKrishna
    Aug 11, 2019

    Can i use single license on multiple devices?. Cause i have 3 studios.

    • Adam Szabo
      Aug 11, 2019

      Yes, as long as they are your own computers

  • eric roulston
    Aug 15, 2019

    so i have a desktop and a laptop for live, i can use on both?

    • Adam Szabo
      Aug 15, 2019

      Yes thats fine

  • GregGrok
    Aug 15, 2019

    I would also like to pick up this vst on sale..
    does the newsletter come out on any schedule ?

    • Adam Szabo
      Aug 16, 2019

      Subscribe to the newsletter and you will get info about sales when it happens

  • Benjamin Brooker
    Sep 14, 2019

    Do you do Educational discount? I’ve been trying to find a solid virus like emulation for years and this looks the real deal.

    • Adam Szabo
      Sep 14, 2019

      There will be discounts at the end of the year.

  • Andre
    Sep 16, 2019

    Any news for mac users?

  • Edy Williams
    Sep 22, 2019

    Any news for mac users?

  • Eddie
    Sep 27, 2019

    Hey Adam. The synth looks and sounds amazing (judging by the demo). I have a Virus TI but I’m thinking about getting Viper nonetheless. Will Viper have more Filter Shapes in the future? I see that the filters are LP4 and LP2. That would be amazing!

    • Adam Szabo
      Sep 27, 2019

      Yes, new Filter Shapes could be a possibility in the future!

  • Reinis
    Sep 29, 2019

    I really really love this synth. It sounds practically identical to a real Virus, which is fantastic! I have a suggestion though – how about adding multisaw sync in a future update? That would pretty much nail it feature-wise.
    Either way, fantastic work Adam. 🙂

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