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


1 4 5 6 7 8 18
  • digital experience
    Apr 02, 2018

    I’m waiting for the 64 version impatiently

  • Mark Hofland
    Apr 04, 2018

    Me too!! I’m running Cubase Pro 9.5 64 bit, so if the 64 bit version comes out I’ll absolutely buy it!

  • Gabriel Navarro
    Apr 04, 2018

    Defintively loving how it sounds! Can’t wait for the 64-bit version to come out!

  • Gianfranco
    Apr 07, 2018

    When a Mac version?

  • Byron Capta King
    Apr 09, 2018

    I really do look forward to the 64 bit version as well. On a particular preset I created I get crackles. I have a fairly fast computer, overclocked a bit too.

    One thing that would be great, and would alleviate this importance (for me) of a 64 bit version temporarily, would be to allow more flexibility in setting the polyphony. Currently it jumps to 8 and 16 from off. Other plugins tend to allow incremental increase/decrease, by one voice at a time.

    I’m not sure specifically why there is crackling – but per Reaper’s performance indicator the CPU usage is below 15% but this seems to max out Viper as a 32 bit wrapper plugin – but then again, that’s typical for Reaper – I haven’t read the articles on the Reaper Performance indicator in awhile. Of course, I confirmed that the issue was polyphony, since when I decreased poly to 8 that resolved it.

  • Justin
    Apr 13, 2018

    Soooooo good!! You’re doing God’s work. Thank you!

  • Muzikfreq
    Apr 17, 2018

    Well now…. I was looking at jp6k videos and rolled upon this. This is massive… Not the one from NI but figuratively speaking

    Apr 21, 2018

    economical and fantastic ability to design original sounds for all kinds of dance music.

  • Quantize
    Apr 27, 2018

    Really can’t wait for the Mac version to come out.

Leave a Reply

Your name here
Your name here
Feb 26, 2020

Gravatars are enabled. Register for free!


  • Your cart is empty.

Follow on Facebook