INSTRUo cruïnn Analogue Stereo Oscillator User Manual
- June 3, 2024
- INSTRUO
Table of Contents
INSTRUo cruïnn Analogue Stereo Oscillator
Description
- The Instruō cruïnn is an analogue stereo oscillator that utilises through-zero phase modulation to create deep, animated textures.
- On top of its single sawtooth oscillator core, cruïnn produces five additional parallel phase-displaced sawtooth variants – each controlled by their own discrete internal triangle waveform LFO. With both on-board and external control over the LFO rates and modulation depths, cruïnn effortlessly creates, super-super-super-super-super saws, lush pads, phasey basses, and chaotic effects.
- With cruïnn’s included passive 4 HP Expander, access to all six waveforms are available. Add to that the ability to individually displace the phase of each waveform via CV and cruïnn becomes an amorphous swarm of harmonically rich sawtooths.
Features
- Stereo and summed outputs
- Six phase-displaced sawtooth variants
- Five internal triangle waveform LFOs
- Global rate and depth modulation controls
- Built-in stereo VCA
- Linear and exponential frequency modulation
- LFO functionality
- Includes 4 HP passive waveform and CV expansion module
Installation
- Confirm that the Eurorack synthesizer system is powered off.
- Locate 14 HP of space in your Eurorack synthesizer case. Locate an additional, but optional 4 HP of space in your Eurorack synthesizer case for the included expander.
- Connect the 6 pin side of both IDC expansion cables to both of the 2×3 pin headers on the back of the main module, confirming that the red stripes on the expansion cables line up with the indicators on the main module.
- Connect the 6 pin side of both IDC expansion cables to both of the 2×3 pin headers on the back of the expansion module, confirming that the red stripes on the expansion cables line up with the indicators on the expansion module.
- Connect the 10 pin side of the IDC power cable to the 2×5 pin header on the back of the module, confirming that the red stripe on the power cable is connected to -12V.
- Connect the 16 pin side of the IDC power cable to the 2×8 pin header on your Eurorack power supply, confirming that the red stripe on the power cable is connected to -12V.
- Mount the Instruction in your Eurorack synthesizer case.
- Power your Eurorack synthesizer system on.
Note:
- This module has reverse polarity protection.
- Inverted installation of the power cable will not damage the module.
Specifications
- Width: 14 HP + 4 HP Waveform and CV Expansion Module
- Depth: 27mm
- +12V: 180mA
- -12V: 180mA
adjective (shape) well developed in all aspects; complete and balanced, plump, fat, full-toned or sonorous
Key
- Left Output
- Right Output
- Sigma Output
- Coarse
- Fine
- 1V/Oct Input
- LFO Toggle
- FM Input
- FM Attenuator
- Lin/Exp Toggle
- Level
- Level CV Input
- Level CV Attenuator
- Rate
- Rate Modulation CV Input
- Rate Modulation CV Attenuator
- Depth
- Depth Modulation CV Input
- Depth Modulation CV Attenuator
- Individual Waveform Outputs
- Individual Rate Modulation CV Inputs
Waveforms
- Right: The Right jack outputs bipolar sawtooth waveforms 1, 2, and 3
- Left: The Left jack outputs bipolar sawtooth waveforms 4, 5, and 6. Sigma ( )Σ : The Sigma ( )Σ jack outputs of all bipolar sawtooth waveforms.
Frequency / Pitch
Coarse: The Coarse knob controls the fundamental frequency of the oscillator’s core. It determines the fundamental pitch of the core waveform.
- Turning the knob anticlockwise will decrease the frequency.
- Turning the knob clockwise will increase the frequency.
Fine: The Fine knob is used for minute control of the oscillator’s fundamental frequency and is relative to the frequency value set by the Coarse knob. It also determines the fundamental pitch of the core waveform.
- Turning the knob anticlockwise will decrease the frequency.
- Turning the knob clockwise will increase the frequency.
1V/Oct: The 1V/Oct input is a bipolar control voltage input that is calibrated to 1 Volt per Octave.
- This is traditionally used with pitch-related control voltages sent from a sequencer or keyboard.
- Control voltage is summed with the values set by the Coarse and Fine knobs.
LFO: The LFO toggle lowers the frequency ranges of the waveforms, allowing for oscillations within subsonic territory.
Frequency Modulation
FM: The FM input is a bipolar control voltage input for the frequency parameter.
- Control voltage is scaled by the FM Attenuator and summed with the values set by the Coarse and Fine knobs as well the value set by the 1V/Octave input.
FM Attenuator: The FM Attenuator determines the depth of frequency modulation applied to the fundamental frequency.
- Turning the knob anticlockwise will decrease the depth of frequency modulation if an external signal is present at the FM input.
- Turning the knob clockwise will increase the depth of frequency modulation if an external signal is present at the FM input.
Lin/Exp : The Lin/Exp toggle sets the FM input to have either a linear FM or exponential FM response curve.
- If the toggle is set to the left position, the FM signal will apply with linear scaling.
- When modulated with a linear FM response, negative voltage will result in an increase in frequency while positive voltage will result in a decrease in frequency.
- If the toggle is set to the right position, the FM signal will apply with exponential scaling.
- If the toggle is set to exponential FM and the FM Attenuator is fully clockwise, the FM input will essentially track at 1V/Octave (Its tracking may slightly differ from the calibrated 1V/Oct input).
Amplitude Modulation
Level : The Level knob determines the amplitude of the stereo and Sigma ( )Σ outputs.
- Turning the knob anticlockwise will decrease the output amplitude.
- Turning the knob clockwise will increase the output amplitude.
- To eliminate any chance of hard clipping that may occur when parallel sawtooth waves sum with perfect phase alignment, a soft clipping circuit is implemented and limits the amplitude range to ~10Vpp. This essentially turns the built-in VCA into a voltage-controlled saturator that can accentuate a nonlinearity of the sawtooth waveforms.
Level CV: The Level CV input is a bipolar control voltage input for the Level parameter.
- Control voltage is summed with the Level knob position.
Level CV Attenuator: The Level CV Attenuator determines the depth of modulation applied to the Level parameter.
- Turning the knob anticlockwise will decrease the depth of amplitude modulation if an external signal is present at the Level CV input.
- Turning the knob clockwise will increase the depth of amplitude modulation if an external signal is present at the Level CV input.
Phase Modulation
Rate : The Rate knob controls the rate of the five triangle waveform LFOs used for phase modulation of the five phase-displaced sawtooth variants.3
- Turning the knob anticlockwise will decrease the rate of the triangle waveform LFOs down to stalling.
- Turning the knob clockwise will increase the rate of the triangle waveform LFOs.
Rate Indicators: The Rate Indicators are LEDs that show the rate of each triangle waveform LFO.
Rate Modulation CV: The Rate Modulation CV input is a bipolar control voltage input for the Rate parameter.
- Control voltage is summed with the Rate knob position.
Rate Modulation CV Attenuator: The Rate Modulation CV Attenuator determines the depth of modulation applied to the Rate parameter.
- Turning the knob anticlockwise will decrease the depth of LFO rate modulation if an external signal is present at the Rate Modulation CV input.
- Turning the knob clockwise will increase the depth of LFO rate modulation if an external signal is present at the Rate Modulation CV input.
Depth: The Depth knob controls the depth of phase modulation applied to
the five phase-displaced sawtooth variants by the five triangle waveform LFOs.
Depth CV Modulation: The Depth CV Modulation input is a bipolar control
voltage input for the Depth parameter.
- Control voltage is summed with the Depth knob position.
Depth Modulation CV Attenuator: The Depth Modulation CV Attenuator determines the depth of modulation applied to the Depth parameter.
- Turning the knob anticlockwise will decrease the depth of Depth modulation.
- Turning the knob clockwise will increase the depth of Depth modulation.
Waveform and CV Expansion
Individual Waveform: The Individual Waveform outputs provide discrete access to the core sawtooth waveform, as well as the five parallel phase- displaced sawtooth waveform variants.
- All Individual Waveform outputs are unipolar positive.
Individual Rate Modulation: The Individual Rate Modulation inputs are bipolar control voltage inputs for the Rate parameters of the five parallel phase-displaced waveform variants.
- Negative voltage will displace the phase forward from the core waveform.
- Positive voltage will displace the phase backward in time core waveform.
Patch Examples
East Coast Synth Voice:
Summary: The sequencer or keyboard sends voltages to cruïnn while simultaneously triggering the envelope generator. The CV output of the envelope generator opens a filter and VCA, allowing cruïnn to pass through. More traditional East Coast patches would incorporate separate envelope generators for the filter and VCA.
Audio Path:
- Set the LFO toggle to its up position, so that the module oscillates at audio rate.
- Set the Level knob to 9:00 so that signal is present at the various waveform outputs.
- Connect the Sigma ( )Σ output to the audio input of a filter.
- Connect the audio output of the filter to the audio input of a VCA.
- Monitor the audio output of the VCA.
- Set the fundamental frequency to a desired position using the Coarse and Fine knobs.
- Set the cutoff frequency of the filter to a desired position.
- Set the resonance of the filter to a desired position.
- Set the gain of the VCA to its minimum position if applicable.
Control Path:
- Connect the 1V/Oct output of a sequencer or keyboard to the 1V/Oct input.
- Connect the gate output of the sequencer or keyboard to the trigger input of an envelope generator.
- Connect the CV output of the envelope generator to a multiple.
- Connect one copy of the envelope generator CV signal to the CV input of the filter and set the corresponding CV attenuator to a desired position.
- Connect a second copy of the envelope generator CV signal to the CV input of the VCA and set the corresponding CV attenuator to a desired position.
- Set the envelope stages to desired positions.
Super Saw Synth Voice:
Summary: The sequencer or keyboard sends voltages to cruïnn while simultaneously triggering the envelope generator. The CV output of the envelope generator opens a filter and VCA, allowing cruïnn to pass through. Depth and Rate parameters are increased to apply phase modulation. More traditional East Coast patches would incorporate separate envelope generators for the filter and VCA.
Audio Path:
- Create an East Coast Synth Voice audio path.
- Set the Depth knob to 3:00.
- Set the Rate knob to 10:00.
Control Path:
- Create an East Coast Synth Voice control path.
Stereo Super Saw Synth Voice:
Summary: The sequencer or keyboard sends voltages to cruïnn while simultaneously triggering the envelope generator. The CV output of the envelope generator opens two VCAs, allowing cruïnn to pass through. Two LFOs modulate the cutoff frequencies of two filters, creating a stereo modulation. Depth and Rate parameters are increased to apply phase modulation
Audio Path:
- Create an East Coast Synth Voice audio path using the Left and Right outputs.
- Use two filters and two VCAs instead of one filter and one VCA
- Set the Depth knob to around 3:00.
- Set the Rate knob to around 10:00.
Control Path:
- Create an East Coast Synth Voice control path, but instead of controlling the filters with the envelope generator, use two unsynced LFOs.
FM Synth Voice:
Summary: The secondary oscillator, called the Modulator in an FM patch, is modulating the frequency of cruïnn, called the Carrier in an FM patch. The sequencer or keyboard sends voltages to cruïnn while simultaneously triggering the envelope generator. The CV output of the envelope generator opens the filter and VCA, allowing cruïnn’s signal to pass through. More traditional East Coast patches would incorporate separate envelope generators for the filter and VCA.
Audio Path:
- Create an East Coast Synth Voice audio path.
Control Path:
- Create an East Coast Synth Voice control path.
- Connect the sine waveform of a separate oscillator to the FM input of cruïnn.
- Set the FM Attenuator to a desired position.
- Set the Lin/Exp toggle to a desired position.
- Most East Coast synthesizers were traditionally limited to linear frequency modulation only
Apocalypse Helicopter:
Summary: This patch utilizes phase modulation, frequency modulation, and unbalanced amplitude modulation to create a helicopter sound effect
Audio Path:
- Set the LFO toggle to its up position, so that the module oscillates at audio rate.
- Set the Level knob fully anticlockwise so that signal is not present at the various waveform outputs.
- Set the Depth knob fully clockwise.
- Set the Rate knob fully clockwise.
- Set the Coarse knob between 9:00 and 10:00.
- Set the Fine knob to 12:00.
- Monitor from the Sigma output
Control Path:
- Connect a triangle waveform LFO to the Level input and set the Level CV input fully clockwise.
- Connect a sine waveform LFO with the same rate and phase as the previously used triangle waveform LFO to the FM input and set the FM Attenuator to 1:00.
- Tune the frequency of the LFOs to desired positions.
- Set the Lin/Exp toggle to its right position to set exponential FM.
Manual Author: Collin Russell
Manual Design : Dominic D’Sylva
This device meets the requirements of the following standards: EN55032,
EN55103-2, EN61000-3-2, EN61000-3-3, EN62311.