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


  • Trap DJ
    Feb 02, 2018

    64-bit PLEASE!!!!!!!

    • Adam Szabo
      Feb 02, 2018

      Its coming calm down. It doesnt magically fall down from the sky, I have to actually work on it, its done when its done.

    • Stefan L
      Feb 19, 2018

      Desperately hoping for a 64 bit Version too. (Since the latest Version of Steinberg`s Cubase does not work with 32 bit plug Ins..)

  • Sergey
    Feb 06, 2018

    Hi Adam. Thank you for your job.
    Viper demo v1.0 at Ableton can not be automated any parameter but at FL all automated normaly.Please tell me it bug or demo restriction?

    • Adam Szabo
      Feb 06, 2018

      I think it a bug, its supposed to work in Ableton. I am working on it.

      • Sergey
        Feb 06, 2018

        Also noticed the following bug (it happens randomly after continuously using) GUI sections such as Oscilator viewing,Filter selection, Saturation selection, Routing selection – stuck GUI viewing when i try to change any parameter, but with sound changes all ok.Also it can happen when i try to change preset – GUI viewing stuck but sound ok.
        Thank you for reply.

  • Kenneth
    Feb 06, 2018

    Mac version and I would have bought it

  • Tommy
    Feb 11, 2018

    Interesting one, but wondering about sound banks for it? Will Watch the development of this one, but most interested to see where we are when the 64-bit version arrives. Hopefully also more sounds available then.

    • Elektro815
      Feb 22, 2018

      Me too!

  • Alexander Spitsyn
    Feb 11, 2018

    My name is Alexander Spitsyn
    Really liked your synth Viper
    There are several suggestions for improvement to work with it You can make it so that the browser presets have been divided into two parts, on the left for the can,and on the right for the presets,choose the Bank on the left,and on the right of presets from it,it is not convenient to load banks from the menu,and add the function of copying,deleting, renaming presets directly in the browser…
    It is not bad yet, to make the gain in the equalizer from 16dB to 24dB
    Presets in the browser switch for a long time for 1-2 seconds
    And of course you need x64
    Excellent Viper synthesizer!

  • Daniel Craighead
    Feb 13, 2018

    Hi Adam,
    the Mid EQ is not responding when setting it as a target in the matrix with the source to Modulation Wheel (not sure if it was gain or freq though). Just reporting what I can find… Thanks for Viper!

    • Adam Szabo
      Feb 14, 2018

      You should definitely show a video because it works perfectly fine for me. Maybe you are not using it right?

      • Daniel Craighead
        Feb 18, 2018

        Sorry was my bad, works perfectly. Seems that it didn’t cut through some sounds themselves…

  • R
    Feb 14, 2018

    Is it possible to load in my virus presets/banks? Would be nice though!

    • Adam Szabo
      Feb 14, 2018

      Umm no. Its like asking if Serum can load Sylenth1 presets. They are totally different synths

  • Springer Coil
    Feb 15, 2018

    I emailed support a little while ago. I was inquiring whether we would hear from you regarding updates or additional presets. Nothing back so I’m guessing you are very busy. This is a pretty interesting synth right away, but I always like to get the latest and greatest. I recommended you to Plugin Guru for a review.

    • Adam Szabo
      Feb 15, 2018

      I didnt seem to get any email. Yes there will be updates and more soundbanks.

    Feb 15, 2018

    Im going to subscribe as soon as its available for Mac
    I will Buy it

  • Gennady
    Feb 21, 2018

    Could you open a couple of future of Viper. Will it simulate remainig parts of VirusTI? I mean, for example additioanl oscilators. If Yes? I will buy Viper very soon, and start to wait for upgradres

    • Adam Szabo
      Feb 21, 2018

      Yes I have lots of ideas and plans for the future!

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