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


  • Reef
    Jan 09, 2018

    Wow, looks super cool! unfortunatly my Daw only supports 64 bit. So i will have to wait for that. Great job.

  • tf
    Jan 09, 2018

    waiting for 64bit, who even uses 32bit nowadays?

    • Ronald Schmidt
      Jan 10, 2018

      It works perfect with jbridge.
      Why wait?
      I am very happy with it. 🙂

  • Frozen Dream
    Jan 10, 2018

    Hello, i have a question, i’d like to buy it with friend.
    is it possible to share the same licence?

  • Sirius Quarks
    Jan 10, 2018

    Yes love the clean interface. Will have to wait for the 64bit version though, Imagine it will sound even better!

    • gbusman
      Jan 11, 2018

      it will not, no sound difference b/t 32 and 64, only RAM utilization
      You would think Ableton could just build that in, can’t wait to try it once I finally can

  • Ray
    Jan 10, 2018

    No Mac ????????????

  • Aernout Ackermans
    Jan 11, 2018

    Need this on my MAC please :o)

  • The victim Official
    Jan 11, 2018

    bye bye Acces Virus

  • Cunt
    Jan 11, 2018

    Looks nice. Only x86 is a big, big issue. Jbridge sucks!

    • tf
      Jan 12, 2018

      Totally agree, serious issue. Nowadays a developer should start with 64bit Version. 64bit should come out first, I don’t know any music producer who works on 32bit anymore… Since a few years actually…

  • Reg Maklinsky
    Jan 12, 2018

    Waiting for 64 bit native before buying.

    • Ronald
      Jan 12, 2018

      As I said, on my System it runs perfect with jbridge,
      No reason to wait on 64 bit. ??

  • JB
    Jan 13, 2018

    Many people complain about 64-bit version… Well, let’s face the truth and stop these more or less senseless #!”£! Almost every major DAW is available in both 32/64. Some of them with native build bridge to support both 32/64 plug-ins (ie. Bitwig). Ask yourselves: Why? No-one uses 32-bits anymore? Don’t be pathetic, please… As far as I understand Mac users expectations PC musicians always have a problem. Nothing new, isn’t it? I’ve been running Viper Demo in few DAWs: Studio One, Bitwig, Sonar Home Studio and have to say its smooth, fast and with absolutely no problems. I don’t know what Access will do next.., but won’t be surprised if they develop Virus in VST mode 😉 Regards.

    • Ronald
      Jan 13, 2018

      I agree to you!
      It makes no sense to discuss about 64 bit
      when it works perfect with jbridge.

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