Cursus Iteritas - Electronic musical instrument Noise Engineering - Free user manual and instructions

Product Type	Eurorack synthesizer module (digital oscillator)
Width	8 HP (40.3 mm)
Height	3U (128.5 mm)
Depth	30 mm (approx.)
Weight	100 g
Power Supply	+12V: 100 mA, -12V: 20 mA (typical)
Audio Output	1x 3.5 mm mono jack, 10 Vpp
CV Inputs	Multiple 3.5 mm jacks, 0–5 V or ±5 V range
Main Functions	Three digital oscillators with basic, waveshaping, and noise algorithms; modulation via CV and knobs
Controls	Knobs for pitch, waveshape, modulation amount, mode selector
Sampling Rate	48 kHz, 24-bit
Firmware Upgrade	Via USB port (micro-USB) and computer software
Construction	RoHS compliant, assembled in USA
Maintenance	Wipe with dry cloth; avoid moisture and static discharge
Safety	Do not exceed stated power supply limits; use in well-ventilated rack
Spare Parts / Repair	Contact Noise Engineering support; module is not user-serviceable
Compatibility	Standard Eurorack cases with sufficient power

Frequently Asked Questions - Cursus Iteritas Noise Engineering

How do I update the firmware on the Cursus Iteritas?

Connect the module to your computer via the micro-USB port. Download the latest firmware from the Noise Engineering website and use the Noise Engineering firmware tool to flash it. Ensure the module is powered via the Eurorack bus during update.

What are the CV input voltage ranges?

The CV inputs accept 0 to +5 volts for unipolar signals and -5 to +5 volts for bipolar signals. Exceeding these ranges may cause clipping or damage.

Can I use the Cursus Iteritas with other Eurorack modules?

Yes, it is fully compatible with standard Eurorack systems. Use patch cables to connect audio and CV outputs/inputs to other modules. Ensure your power supply can handle the current draw.

What is the power consumption of the module?

Typical power draw is +12V: 100 mA and -12V: 20 mA. Check your rack's power supply to ensure total consumption is within limits.

How do I reset the Cursus Iteritas to factory defaults?

To reset, press and hold the mode button while powering up the module. All settings will revert to factory defaults. Refer to the manual for exact procedure.

What is the audio output level?

The output delivers a maximum of 10 volts peak-to-peak (Vpp) on a 3.5 mm mono jack. Use attenuators if connecting to inputs expecting lower levels.

How can I create bass sounds with the Cursus Iteritas?

Set the mode to 'Basic' oscillator, lower the pitch knob, and use the waveshape control to add harmonics. Modulate with a slow envelope or LFO for movement.

Is the Cursus Iteritas polyphonic?

No, it is a monophonic oscillator module. It produces one voice at a time. For polyphony, use multiple modules or a polyphonic voice controller.

How do I modulate the pitch with an external CV?

Connect a CV source (e.g., an LFO or sequencer) to the 'Pitch CV' input. The module will respond to voltages in the 0-5V range for 1V/octave tracking (after calibration). Use the pitch knob to set a base frequency.

What does the mode switch do on the Cursus Iteritas?

The mode switch selects between three oscillator algorithms: Basic, Waveshaping, and Noise. Each offers different tonal characteristics. The selected mode affects the core sound generation.

USER MANUAL Cursus Iteritas Noise Engineering

Noise Engineering Cursus Iteritas

Dynamically generated wavetable oscillator using orthogonal functions.

Type LFSR VCO

Size 10HP Eurorack

Depth 1.5 Inches

Power 2x8 Eurorack

+12 mA 150 / 80 (if 5v on)

-12 mA 5 / 5

+5 mA 0 / 90 (optional)

Cursus Iteritas is an oscillator that works from a dynamically generated wavetable. It gives the user spectral-like controls over three different modes based on different conceptualizations of frequency: Fourier, which uses sine waves; Daubechies, using wavelets, and Walsh mode, using the Walsh transform. Cursus Iteritas parametrizes a wide variety of sounds, but because the sounds are all based off of orthogonal functions, it has a musical tone structure and can produce an extremely wide variety of harmonic sounds.

graph TD
    A["Cursus Iteritas"] --> B["Pitch"]
    A --> C["Center"]
    A --> D["Structure"]
    A --> E["Edge"]
    A --> F["Width"]
    A --> G["Tilt"]
    A --> H["Fold"]
    A --> I["Daubechies Fourier Walsh"]
    A --> J["Bass Alto Treble"]
    B --> K["Pitch"]
    C --> L["Center"]
    D --> M["Structure"]
    E --> N["Edge"]
    F --> O["Width"]
    G --> P["Tilt"]
    H --> Q["B/A/T"]
    I --> R["Out"]
    J --> S["Sync"]
    K --> T["Struct"]
    L --> U["Fold"]
    M --> V["Sync"]
    N --> W["Sync"]
    O --> X["Sync"]
    P --> Y["B/A/T"]
    Q --> Z["Out"]

Noise Engineering

Noise Engineering Cursus Iteritas

Dynamically generated wavetable oscillator using orthogonal functions.

Interface

All knobs on Cursus Iteritas function as offsets for the input jacks. The controls function similar to a bandpass filter; center, width, and tilt allow the filter to be asymmetric.

Pitch

1v/8va pitch control. For more control, see Range below.

Center

selects the center harmonic used to build the wavetable.

Structure

allows selection of harmonics included in the output. In the center position, all harmonics are included. Fully left only even harmonics; fully right, only odd.

Edge

controls the oversampling filter of the wavetable. As this is turned to the right, it will add musical overtones.

Fold

wavefolder. Enough said.

Width

controls how many different harmonics are used to create the wavetable.

Tilt

weights the spread of harmonics. In the middle it is symmetric; at left, lower harmonics are louder while at right, higher harmonics get more volume.

Sync

triggers edge-based oscillator reset

Mode

selects which orthogonal function set is used to produce the wavetable

Range

two-octave offset pitch ranges

Out

audio output - 10vpp

graph TD
    A["Cursus Iteritas"] --> B["Pitch"]
    A --> C["Center"]
    A --> D["Structure"]
    A --> E["Edge"]
    A --> F["Fold"]
    A --> G["Width"]
    A --> H["Tilt"]
    A --> I["Daubechies Fourier Walsh"]
    A --> J["Bass Alto Treble"]
    B --> K["Pitch"]
    C --> L["Center"]
    D --> M["Structure"]
    E --> N["Edge"]
    F --> O["Width"]
    G --> P["Tilt"]
    H --> Q["D/F/W"]
    I --> R["B/A/T"]
    J --> S["Out"]
    K --> T["Struct"]
    L --> U["Fold"]
    M --> V["Sync"]
    N --> W["Output"]
    O --> X["Output"]
    P --> Y["Output"]
    Q --> Z["Output"]

Noise Engineering Cursus Iteritas

Dynamically generated wavetable oscillator using orthogonal functions.

Patch Tutorial ☐ - Introduction

The easiest way to get to know Cursus is to just plug in the output and play with the knobs to get a feel for the sounds it can make.

Patch Tutorial 1 - Gates and LFO

Cursus works very well with any LFO, gate or envelope source the more the better. Patching the outputs of the Numeric repetitor directly into the parameter inputs on Cursus is a great way to generate complex rhythmic tonality variation.

Every LFO source is fun with Cursus. We highly recommend patching Sinc Iter, Malekko Voltage Block, Malckko AD/LFO, Mannequins Just Friends, Make Noise Wogglebug, and WMD PDO with Cursus.

We will be updating this with pictures, more examples and videos very soon!

Noise Engineering Cursus Iteritas

Dynamically generated wavetable oscillator using orthogonal functions.

Tone Generation

Cursus Iteritas generates a spectral description based on knob positions. Center, Width, Tilt, Structure determine amplitudes for each harmonic. This description is fed into the inverse transform for the current function set to produce the time-domain wavetable. The wavetable is normalized to reduce amplitude variations across spectral changes.

Oversampling of the wavetable depends on pitch: lower octaves have higher oversampling since the sample rate only varies by a factor of two. The Edge control interpolates the oversampling from point sampling to a cubic-spline interpolation (NURBS). As the period of the full length of the wavetable always evenly divides the sample rate, the additional aliasing is largely harmonic in nature. Fold controls the signal wavefolding.

In many places in the signal path, there are soft clipping stages to mimic analog-style clipping to give more warmth and complexity to the sounds generated.

Noise Engineering

Noise Engineering Cursus Iteritas

Dynamically generated wavetable oscillator using orthogonal functions.

Variable Sample Rate

Cursus Iteritas uses a sample rate that is a multiple of the fundamental (lowest) oscillator frequency. This moves alias power that is a multiple of the fundamental to be mapped to a multiple of this tone, therefore making the aliasing align with the harmonics of the tone. This works well for settings with a strong harmonic structure (spread fully CW or fully CCW) and adds unique aliasing character for other tones.

Calibration of Tuning

Cursus comes pre-calibrated but over time it may change and need a touch up.

Pitch calibration is controlled by an linear resistor-divider network. To calibrate the tuning, attach a volt meter (preferably 4+ digit) to the test points TPCV and TPGND on the rear panel and adjust the trim pot.

The voltage measured should be 5/16 (.3125) times the input voltage applied to the CV input. A reasonable way to tune the scale is to use an adjustable voltage source to generate 4 volts then adjust the tuning trim until the test points read 1.2500V. Cursus Iteritas can also be tuned using a reference supply capable of generating a 1 volt difference and using a stroboscope such as the Peterson 490 to tune to an octave interval. This is method is preferred to the meter-only method.

Voltage Supply

Cursus Iteritas can run its processor on the 5V eurorack power rail to reduce noise and load on the 12V bus. Gently push the switch tab in the direction of the desired rail to use.

Close-up of a printed circuit board with integrated circuits and connectors (no readable text or symbols)

Noise Engineering Cursus Iteritas

Dynamically generated wavetable oscillator using orthogonal functions.

Genesis and Design Notes

This module started many years ago when Scott Jager and Yasi Perera turned me onto Walsh functions.

The big question was how to reduce the large number of variables (32 harmonic volumes for a 32 band Walsh synthesizer) into a reasonable control set. Bandpass filter-like controls seemed to be a good solution and there already exist similar controls in the various existant Harmonic Oscillators. A software prototype was written that proved that a sequence bandpass control scheme was usable. The then project went to sleep for a couple years as other modules took priority.

When I started working on it again I wanted it to have three modes much like our other current modules so I went searching for other orthogonal function sets that could fit in the same control scheme.

The Fourier Series was an obvious second set of orthogonal functions to use which perfectly mapped to the bandpass-like controls.

Modern mathematics have given us an ocean of orthogonal function sets in wavelets so that seemed another good place to look. The Daubechies 4 wavelet fit the bill being easy to compute and having an interesting—and somewhat sawtooth-like—waveform. The controls were a little less natural since this wavelet has more time precision and more frequency redundancy. With some work however it worked out quite naturally.

Noise Engineering

Noise Engineering Cursus Iteritas

Dynamically generated wavetable oscillator using orthogonal functions.

Special Thanks

Kris Kaiser Scott Jager Yasi Perera Shawn Jimmerson Eric Cheslak Bana Haffar William Mathewson Mickey Bakas Tyler Thompson Alex Anderson

References

Hutchins Jr, Bernard A. "Experimental electronic music devices employing Walsh functions." Journal of the Audio Engineering Society 21.8 (1973): 640-645.

Brown, Owen. A Digital Waveform Synthesizer Using Walsh Functions. Diss. 1971.

Rozenberg, Maurice. "Microcomputer-controlled sound processing using Walsh Functions." Computer Music Journal (1979): 42-47.

graph TD
    A["Cursus Iteritas"] --> B["Pitch"]
    A --> C["Edge"]
    A --> D["Width"]
    A --> E["Center"]
    A --> F["Tilt"]
    A --> G["Fold"]
    A --> H["Structure"]
    A --> I["Daubechies Fourier Walsh"]
    A --> J["Bass Alto Treble"]
    B --> K["Pitch"]
    C --> L["Edge"]
    D --> M["Width"]
    E --> N["Center"]
    F --> O["Tilt"]
    G --> P["B/A/T"]
    H --> Q["Structure"]
    I --> R["Fold"]
    J --> S["Sync"]
    K --> T["Noise Engineering"]
    L --> U["Out"]

Noise Engineering