Title of Module

[Overview of module]

Buchaudulus is a project I created to explore synthesis methods available in Buchla’s Music Easel. Though, some inspiration was drawn from the Music Easel, this is not an Easel clone.

This is a work-in-progress and I invite others to tinker and improve it.

Acknowledgement: Much of the guts Buchaudulus is taken from modules created and posted by others. Hopefully, I have remembered to acknowledge them inside the sub-patches that use their code. This project is largely a Frankensteining of parts created by others. People whose modules were borrowed from include: Mark Boyd, Robert Syrette (whose 0-Toast patch led me to the rabbit hole that became the Buchauduls project), stschoen and Rudiger Meyer. Many many thanks to them

Apologies for the user interface mess. Since the project was largely an explorer that was (and is) constantly in flux, the user interface is untidy. Sorry.

The heart of Buchaudulus is TheCO (the complex oscillator). Its major parts are:

  • The Principal Oscillator
  • The Mod(ulating) Oscillator
  • Wavefolder algorithm selector
  • AM algorithm selector
  • Mixer
  • Patchbay


In order to make it easier to pass signals from modules on one side TheCO to other modules, there is a patchbay that allows you to pass signals around conveniently.

Each edge of TheCO has a bank of 5 numbered input and output nodes. Each input node is connected to the other corresponding output nodes. So, if you connect something (let’s say a gate signal) to the left side’s input 1, it is sent to all the output 1 nodes of the other patch point banks.

PATCHBAY NOTE: In some of the uploaded patches, there are some patchbay points that are inadvertently wired together (at the topmost level not in the subpatch). If you zoom out in the user interface, you will be able to see the connection. You should disconnect these.

Principal Oscillator

The principal oscillator is a virtual VCO whose base waveform is a user-controllable mix of triangle, sine, saw and variable pulse square wave whose output can be wavefolded, and it can be modulated by the modulating oscillator.

It provides selection of the wavefolding and AM (amplitude modulation) algorithms, and a choice as to where in the signal chain wavefolding happens. (More about that below).

The principal oscillator blends the output of two oscillators: the TriSin oscillator which is a blend of triangle and sine wave and the SawSq oscillator which is a blend of saw and variable-width pulse/square wave. By default, the wavefolder is applied to just the TriSin oscillator (as in the music easel). But there is a switch to allow wavefolding of the TriSin/SawSq mix.

The input, outputs and controls

Pitch input/output. The Prin(cipal oscillator) has a 1/oct input near its title. There is a 1/oct output that passes out the 1/oct input. Usually, this is wired to the modulating oscillator’s 1/oct input.

  • -|+ knob – this is a fine-tuning knob.
  • oct knob – this transposes oscillator up or down by octave.
  • TriSin knob – this knob interpolates between a triangle and a sine wave.
  • CO Mix – this knob controls the blending of the TriSin output and the SawSq output
  • SawSq – this knob controls the blending of Saw wave and Pulse/Square wave which is blended with the TriSin.
  • WF Amt – this knob is sent to the wavefolder to set the wavefolding depth.
  • WF Mix – this knob controls the mix of wavefolded and unwavefolded mix.

Audio Outputs:

  • Modded - The wavefolded output of the principal oscillator. This is the same signal that is passed out of the mixer as the principal oscillator’s output
  • TriSin – Unwavefolded output of the TriSin oscillator
  • Coalt – Unwavefoded output of the SawSq oscillator
  • Mod – While grouped with the Principal Oscillator outputs. This is the output of the modulating oscillator


  • WF MixOsc Button – This toggles between two possible arrangements of the wavefolding and amplitude modulation. When this is off (the default), wavefolding is applied to only the TriSin oscillator which is blended with the SawSq output. That combined signal is then amplitude modulated. When WF MixOsc is on, amplitude modulation is applied a blend of the TriSin and SawSq waves and that result is wavefolded. The default setting mimics the behavior of the music easel where wavefolding is only applied to the sin wave (which is more of a triangle waveform than sin).

WF# knob
This knob provides a choice of wavefolding algorithms which are:

  • 1: 0-Toast Wavefolder: from 0-Toast (not 1-Toast) with Overtone at 0 This was ripped out of Robert Syrette’s original 0-Toast posting and is different from the one used in 1-Toast. (Something to explore: WHAT HAPPENS WITH OVERTONE NOT 0?).
  • 2: WeirdFolder: from the Audulus forum was apparently inspired by Buchla 259. Forum file was called called “my-weirf-wavefolder”
  • 3: Diode Folder (from Audulus forum)
  • 4: Sine Folder (from Audulus forum)
  • 5: RSWF: from (Audulus forum)
  • 6: RSBuchla: from audulus forum spline-based wavefolder that Robert Syrette posted in response to my posting of a paper about digitally re-creating the Buchla Wavefolder
  • 7: RH-RM Waveshaper: Rudiger Meyer’s waveshaper

AM# knob
This knob lets you select the amplitude modulation algorithm. In most cases, this selects a different type of virtual VCA. These VCAs are mostly from the Audulus forum.

AM Algorithms:

  • 1: DiodeVCA
  • 2: ExpVCA
  • 3: TubeVC
  • 4: JFET VCA
  • 5: LogVCA
  • 6: linvca
  • 7: WestCAT algo - this amplitude modulation algorithm was ripped out of the most-excellent WestCat oscillator.


  • 1/oct input - normally this comes from the principal oscillator’s 1/oct output. But you can patch any 1/oct value into it in order to have independent pitches in the Mod and the Prin
  • Track On/Off - when track is on (the default), the modulating oscillator’s pitch is modulated by the 1/oct input. When track is off, the modulating oscillator has a fixed frequency set by its knobs
  • Smooth On/Off -When Smooth is on, the interval (see below) is a continuous adjustment. When smooth is off, the interval value is rounded to the nearest integer.
  • -|+ knob – this is a fine-tuning knob.
  • ivl (interval) knob – sets the pitch offset from -12 to +12 semitones.
  • oct knob – this transposes oscillator up or down by octaves.
  • Tri Saw Sq- switches between the available modulating oscillator waveforms: triangle, saw and square
  • AM AMT – The amount of amplitude modulation applied to the principal oscillator
  • FM AMT – Amount of linear frequency modulation applied to the principal oscillator


The mixer is the most convenient way to grab audio from TheCO. There are buttons to choose which output is sent out the mixer. The M button toggles whether the Modulating oscillator’s output is sent to the mixer or not. The P button toggles whether the Principal oscillator’s output is sent to the mixer. The knobs under the buttons control the amount of each oscillator’s signal that is sent out the mixer output.

In all of the posted examples, there are a number of helper modules that are part of the Buchaudulus system. Key helper components are:

  • Pulser - clock, gate and pitch source
  • 5-Step Sequencer - simple step sequencer for sequenceing pitch and CV
  • Slope module - Slope module from the Audulus library
  • LPGe - my slight customization of the Audulus library’s Low-Pass Gate. I added some knobs for scaling the response in ways that were helpful to me. You might prefer the standard low-pass gate.
  • Stereo Magic - the current version has a couple of stschoen’s uverbs. This module provides dynamic variations in stereo image. This is a super-unrealistic pseudo-quadrophonic. It isn’t realistic, but I think its fun.

More info to follow about the helper modules and their use.

OPTIMIZING: The Buchaudulus module was optimized for flexibility and exploration NOT for CPU-use. The biggest CPU hit is the combined collection of wavefolders and VCAs. You can cut the CPU-use in half by removing all but your favorite wavefolder and amplitude modulation. On my 6th generation iPad (2018 non-pro model), the CPU hit is cut almost in half by deleting all but one wavefolder and VCA. Also, “Stereo Magic” has two reverbs embedded in it. You can save a lot of CPU by removing Stereo Magic and using an external reverb. But, then again, that won’t be magic.

Some tracks recorded with Buchaudulus. Each of these is a single live recording of a single instance of Buchaudulus:

Krellnick’s First Apple is a pseudo-Krell patch put together to help explore the Buchaudulus parameter space:


Input Signal Range Notes
[Screenshot of input] Signal Range [Optional Notes]

Output Signal Range Notes
[Screenshot of output] Signal Range [Optional Notes]


[Knob, Button, Spline, and/or Mapper] Function Notes
[Screenshot of control] [Function] [Optional Notes]


Meter Displays Notes
[Screenshot of display] [What the display does] [Optional Notes]

Version History

Revision File Date Notes
0.56a Buchlaudulus 0.56a Explore.audulus (1018.7 KB) July 14, 2019 first public share


Revision File Date Notes
0.56 Buchaud Examples.zip (682.7 KB) July 14, 2019 Three Buchaudulus example systems: 0.56 dancing AM Groove, Buchlaudulus 0.55 krell uverb, Buchlaudulus 0.56a Basic

Impressive looking piece of work. I’m looking forward to diving into it. :cowboy_hat_face:

A procedural note. When inserting an upload into a table you need to escape the | symbol within the file link by inserting a \ before the |.


Thanks for letting me know.

1 Like

The Uncertain Future modules would be really fun with this.


For “Dancing with Machines” what was your reverb?

1 Like

Dancing with the machine was made with the include file “0.56 dancing AM Groove”. I don’t that no I used any additional reverb other than the Stereo Magic which has two uVerbs inside. If there is another reverb it was probably BLEASS Reverb on iOS.

All my Audulus stuff is done on an iPad, btw.

1 Like

I enjoyed your demo tracks. I had listened to Krellnick’s First Apple previously but hadn’t had a chance to check out the others. I’m flattered that you found some use for the uVerb. Honestly I never been particularly happy with the sound of the uVerb. I had attempted to model it based on the paper “Natural Sounding Artificial Reverberation” by Schroeder, but clearly I haven’t grasped some essential point, since the result is anything but natural sounding. Still it does have a sound of its own I suppose. Your Stereo Magic makes good use of it.

I enjoy uVerb a lot, Of the Audulus reverbs, I have found it the most useful. Not a natural-sounding one, but it creates interesting ambience. If A3 had multiple outs, I would have probably routed the dry audio out of Audulus through four outputs and used external reverbs.

Implementing reverb is a dark art. My sense is that getting from very good to sublime is tough,

Btw, my pseudo-krells are largely a way for me to traverse a large parameter space to evaluate timbral possibilities that are tedious to explore by hand.

I have a few things in process to make them even more useful on that front if I can find the time to hack them. Your new modules are something I want to try out, too.

1 Like

I’m hopeful that the forthcoming A4 AUv3 will support multi-channel I/O. In addition to allowing more creative audio routing, my experiments have demonstrated that, at least for Live and Reaper, it’s possible to route CV style signals. Softube Modular supports 2 input and 8 output channels in addition to the main outputs and the current VCV Rack bridge allows 8 channels of I/O. I have already done some limited testing of CV and audio routing between Audulus, Rack and Softube and hopefully with additional channels available the options will be greatly expanded. I typically use Ableton’s excellent reverbs when working in that context since in general they seem to be way ahead in sound quality.

@espiegel123 Great job man! This thing sounds awesome! I like your Soundcloud uploads, too :smile: