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Here you'll find the FlowStone synth available in Windows VSTi format as free download for your enjoyment...

With the wonderfully bad taste of oldschool 90's visual design, using mainly the saw waveform (hence the name saguaro) combines and mixes saw with sine, triangle, square and noise in selectable pre-wired Osc modules. No analog emulation, no special unison, no stereo FX, no delays nor reverb built in.  Just pure harsh-digital-mono mayhem.

There is no regular oscillator section exposed on this synth, only three main parameter knobs and the fundamental saw adjustment.

This is intentional. Very ROMpler'y indeed... is a highly experimental synth and as such it has some sound issues including clicks and aliasing etc. So beware.

As creator of I am not in any way shape or form an audio/DSP-engineer. I take no responsibility for damages, psychological or otherwise caused by use or misuse of this software. Don't stare at that smiley for too long!  ;-) can be considered a barebone 1 + 1 oscillator synth of sorts

To understand the idea of the synth choose a default (blank) patch and try the different Osc modules. Tweaking P1, P2 and P3.
Adjusting these parameter knobs on an already made preset won't yield a satisfactory change since they are likely already modulated. is a pasttime dabble... so there will likely be more osc modules. When and how many depends ultimately on any public interest for the plugin.

All donations are very much appreciated!

If you enjoy you can show appreciation and support me as a creator by making a Paypal donation. Takes a bit of time putting larger Flowstone schematics together, even technically simple ones. Contributions will encourage future updates and exports as FlowStone is updated. was built for fun and personal learning purposes in 2022.  Using pure distilled silliness and irony

and FlowStone. Naturally.
However it has been updates a few times since then...

Big thanks to MV
His contributions to the FlowStone community made this plugin possible.

MV deals in more advanced audio/image processing than any of the modules of his implemented in

MV's website can be found here

System requirements

Both standalone / vsti version:

  • Microsoft Windows 7, 8 or 10
  • 4-core CPU @ 3.0 Ghz or higher
    Recommended later generation i5/7 @ 3.5 Ghz or higher
    This plugins is demanding in the CPU. You might have to freeze your tracks
  • Up to 1024 megabytes of free RAM (plugin itself)
  • Microsoft Visual C++ Redistributable Package for Visual Studio 2013
  • Sound device with low latency ASIO drivers

    You can emulate ASIO device by using ASIO4ALL driver
    which can be found here:

  • External MIDI-keyboard for Standalone version

Specific to vsti version:

  • A "DAW" software that can host VST2/3 plugins (32 or 64-bit)
    - Compatibilty with any particular DAW is not guaranteed
    - Reaper usually works fairly well

Known issues (most releases)

  • Standalone .EXE version only: Holding down left mouse button and clicking right mouse button at the same time will freeze knobs.  If a knob is frozen the standalone version of the synth has to be restarted.

  • Both VSTi and Standalone version can sometimes be rendered silent. Usually solved by clicking "If synth has issues" button. Alternatively changing program preset or oscillator module.

  • You should always use an ASIO sound device. Playing the synth on a non ASIO sound device sounds awful and usually results in high latency. Please use an ASIO sound device.
    You can emulate ASIO device by using ASIO4ALL driver which can be found here:

    Note: that asio4all is a temporary solution and doesn't always work well, it has it's own issues


April 2023 update NEW

March 2023 fourth update

  • export version 0.44.1

March 2023

  • export version 0.42, 0.43 and 0.44

Upcoming Updates

  • Modulation of S2 & Slice parameters
  • Assignable C1..3 range increase: -2 to +2
  • 2 additional mini LFO's
  • Adjustments/changes regarding Aftertouch
  • More Osc Modules...

Future updates & ideas

  • More osc modules...
  • Polyphonic aftertouch? Not just midi-channel aftertouch
  • Possible addition of P1 & P2 Complex segmentation/stepping
  • Changes in GUI to improve Usability 
  • Fixes, optimizations and minor adjustments


These are possible updates if interest for the plugin

is great enough and it's CPU usage doesn't hit critical levels

even on fast systems screenshot 1/8 screenshot 2/8 screenshot 3/8 screenshot 4/8 screenshot 5/8 screenshot 6/8 screenshot 7/8 screenshot 8/8


Selected features

    • Polyphony: 1 up to 64 voices  (depending on CPU)
      - Voices adjustable
    • 2 Filters
      - Selectable LP/HP/BP/Peaking etc
      Mainly FlowStone toolbox (optimized by MV) 
      - 3 filter routing modes: Parallel, Series 1 and Series 2
    • 5 simple ADSR/AHD envelopes: 1 amp, 2 filter + 2 modulation (flip +-) 
    • 2 non syncable LFOs with standard waveforms
      - Non syncable but can be triggered by automation/manually to hard sync
      - Uni/Bipolar Offset per individual destination
    • 3 custom assignable knob controllers
      - Select input from auxiliary knob, modwheel,
      aftertouch, pitchbend or midi-cc's
      - Controls any number of knobs at the same time
    • Rudimentary pitch to velocity modulation
    • Rudimentary pitch (tracking) modulation
    • Rudimentary pitch to panning option
    • Scalable GUI (freely resizable in VST3 64-bit version)
    • Pitch controls and other basic controls are there...

    • Distortion
      The FlowStone toolbox distortion was adjusted slightly for levels
      and thrown in for good measure. It does have bad aliasing.


    As the FlowStone export of the synth is free... Charging money for or bundling it with other software and selling it without permission is not permitted. Modifying or any part of it's code without permission from it's creator is also not allowed.


    Whats on your mind

    If you have any thoughts, ideas or suggestions surrounding this little VSTi / Standalone synth project. Let me know...

    There is no official support for the synth since it is both free and at the mercy of my ignorance and any behaviour inherent to FlowStone itself.

    But you are welcome to report any bugs or incompatibility issues with different DAWs and/or Windows versions.

    Be aware that messages regarding bugreports and suggestions might not always be answered. But I will read all and take them into consideration...




    Good to know...

    • Hold down SHIFT-key on keyboard for fine adjustment of knobs. LFO frequency is adjustable in steps around 0.001 Hz

    • Easily automate or control multiple parameters such as both filters cutoff at once using one knob. Without creating multiple automation tracks
      Example of using Assignable C1 for direct control over filter 1 & 2 cutoff's...

    • The more automation you do the more CPU is consumed. Especially automating interactively using's own GUI
    • Turn off scope visualization to save a bit of CPU or hide the plugin GUI using the DAW
    • If you experience silence, notes that get stuck, filters, lfo:s or envelopes acting up. Try pressing If synth has issues button
    • DAW host usually saves values (preset/knobs) for VSTi with it's project. This is not the case with Standalone version
    • Loading  banks takes a long time, have patience. Do not close the VSTi / Standalone to early when saving banks and preset to file
    • Programs/presets and banks are in plain text format and can therefore be viewed with any text editor, like Notepad
      They do however contain 3000+ parameters for each program/preset. Thats 80 x 3000+ parameters in one bank

    Proudly presenting my idea emphasizing the G:

    I'll make a synth plugin and call it... uhmm...

    Spanish speaking person next to me:

    - You know it's pronounced Sa-w-uaro... Right?

    A plugin based on saw it is then...