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


  • Joe R.
    Dec 11, 2018

    The new resizeable 1.04 is great to use. Great Pleasure. Thanks for the labour.

  • Monte Emerson
    Dec 13, 2018

    I’m trying to download the update per the instructions recently mailed out but I’m not having any luck.

    • Adam Szabo
      Dec 13, 2018

      The site might have had problems because of the traffic. Just keep trying multiple times

  • Max
    Dec 15, 2018

    Hi Adam, what are you planning in the next patch?

    • Adam Szabo
      Dec 15, 2018

      It should be a bigger update so it will take time, but one feature will be to load own skins 😉

Leave a Reply

Your name here
Your name here
Dec 15, 2018

Gravatars are enabled. Register for free!


  • Your cart is empty.

Follow on Facebook