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


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  • Sergey Klimenkov
    Jan 07, 2018

    OMG Somebody has a synth w/ LFO Phase Offset!! It’s great.
    BTW Could you add every ADSSR stages as a destination into MOD Matrix? So we could change their curves. i.e Flt. Env1—> Flt. Env. Decay. If Increase it is more logarithmix, if decease its exponential.
    The synth “you know which one” has this feature. Cheers!

    Jan 07, 2018

    Super cool sound,Super easy for programming and most important super fun to play with 🙂

  • Silence Groove
    Jan 07, 2018

    loving the demo so far! will consider buying full version, well done mate

  • JDAC
    Jan 08, 2018

    Awesome synth!! I want to buy Mac version!!!

  • Marro77
    Jan 08, 2018

    What about 64 bit,when exactly you planning release?

    • Adam Szabo
      Jan 08, 2018

      I dont know yet, hopefully soon

  • Allen Fremstad
    Jan 09, 2018

    I’ve been looking for a synth like this forever, I’m using it right now and I’d love to collaborate with you on music Adam,

  • Yukio Otomori
    Jan 09, 2018

    I will buy it when I get a 64bit version!

  • Joerg Lamster
    Jan 09, 2018

    Very interesting…but why 32Bits???? I will wait until the 64bit version arrives

  • User5008
    Jan 09, 2018

    Wow. I have to congratulate you on the GUI. That’s way more usable than the synths its inspired from. Looks and sounds awesome. Instant buy!

  • Ronald Schmidt
    Jan 09, 2018

    I just bought it. Contartulations! A fantastic synth.
    A wish for the the future: More pads like “75 PS ambient pad”.
    This pad is the reason why I bought Viper.
    And some more bread and butter sounds and sequences would be nice.
    The edm dance presets are very good but not my style of music. 🙂

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Aug 14, 2020

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