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You've reached the page of the personal project, a polyphonic additive VSTi synth plugin with a slight oldschool 90's visual touch. is a simple synth. It uses mainly the saw waveform (hence the name saguaro) mixed and combined with sine, triangle, square and noise in selectable Osc modules. No analog emulation, no special unison, no stereo FX, no delays nor reverb built in. Just pure harsh-digital-mono mayhem. No "special" internal workings. Well... except for FlowStone's DSP audio engine itself that is, and optimized modules part of the schematics. is a highly experimental synth and as such it has some sound issues including clicks and aliasing etc. So beware. Use it at your own risk and with caution.

I am not in any way, shape or form an audio/DSP-engineer.

As creator of I take no responsibility for damages, personal, psychological :-) or otherwise, caused by use or misuse of this software.

Now that that's out of the way... was built for fun, and personal learning purposes as a small summer project in 2022.  Using pure distilled silliness and irony... and FlowStone... Naturally.

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

MV deals in more advanced audio/image processing than the modules of his implemented in this plugin...

MV's website can be found here is a free VSTi / Standalone synth... just download!

If you enjoy you can show appreciation and support me as a creator by making a Paypal donation. Seems to take a little bit of time putting larger Flowstone schematics together, even simple ones. Contributions will encourage future updates and exports as FlowStone is updated. 

All donations are very much appreciated!

Should you bother with this dime-a-dozen VSTi?

This synth will appeal mostly to those looking to make some harsh electronic style of sounds, but aren't that concerned about fidelity

Maybe you just want to make some wierd sounds using a few presets. Like me!... Yay!!! ergo the birth of the synth. LOL

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... can be considered a barebone 2 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.

Parameter knobs
P1, P2 and P3 adjusts one or more predefined parameter inside the oscillator module at the same time. These knobs functionality vary for every oscillator module. As such the knobs can also be segmented/stepped in their function depending on selected module.
They usually adjust predefined phases and tuning,  internal modulation frequencies, amounts or mix between already level adjusted oscillators and configurations.

In a non scientific way. For better or worse. I just created some modules I felt like. Some of the oscillator modules (multisaw) do typical oldschool rave or techno pad-like sounds, but can be used for other stuff... I guess... ;-) 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.

System requirements

Recommended for running

Both standalone / vsti version:

  • Microsoft Windows 7, 8 or 10
  • 4-core CPU @ 3.0 Ghz or higher
    - Preferably later generation i5 or i7 @ 3.5 Ghz or higher
    This plugins eats CPU for breakfast. You'll just have to freeze your tracks. Sorry I guess? ;-)
  • 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


March 2023 second update NEW

March 2023

  • export version 0.42

Upcoming Updates

  • Modulation of Slice parameter
  • Assignable C1..3 range increase: -2 to +2
  • Additional options for Auxiliary Osc
  • 2 mini LFO's
  • Adjustments/changes to 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

Note: 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

Known issues (all versions)

  • 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 upon startup. Solve by changing program preset or oscillator module.
    Alternatively press the "If synth has issues" button

  • Instances of standalone .EXE version crashing when starting up, switching between presets or if switching between distortion post envelope and pre envelope when playing notes or DAW playing (VSTi version)

  • Shifter knobs (Oct & Semi) don't follow C1, C2, C3 controller input correctly. 

  • 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

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... 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 key features

    • Up to 64 voice polyphony (depending on CPU)
      - Voices can be adjusted freely
    • 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 controls
      - 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 (and fully 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.

    Good to know stuff...

    • Hold down SHIFT-key on keyboard for fine adjustment of knobs/values. The LFO frequencies can be adjusted in steps of 0.001 Hz
    • The Options-menu and the Envelope's smooth trigger ON/OFF (small round buttons)
      Use these settings adjust correct (re)triggering of envelopes. Might be useful when in monophonic mode (1 voice) or if 
      experiencing unecessary clicking when voices are being stolen in polyphonic mode. Some clicks still occur.  

    • 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 when automating interactively using's own GUI
    • Turn off scope visualization to save a tiny 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 the 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
      Programs/presets or banks are best saved before closing VSTi plugin / Standalone and then loaded manually on next session
    • Saving and loading programs/presets and banks takes a while. Please be patient and do not close the VSTi / Standalone to early
    • Programs/presets and banks are in plain text format and can therefore be viewed with any text editor, like Notepad
      They do however contain 1400+ parameters for each program/preset. Thats 64 x 1400+ parameters in one bank


    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 any behaviour inherent to FlowStone itself. But you are still free to report 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...