INSTRUo Dual All Pass Filter User Manual

INSTRUo Dual All Pass Filter

Specifications

• Module Type: Dual All-Pass Filter
• Power Requirement: Eurorack synthesizer system
• Width: 4 HP
• Features: Phase shifting, CV inputs, Pole toggle

Description / Features
The Dual All-Pass Filter module provides two independent all-pass filters for phase shifting audio signals. It features phase sliders, CV inputs for modulation, and a pole toggle to set the filter slope.

Installation

1. Confirm that the Eurorack synthesizer system is powered off.
2. Locate 4 HP of space in your Eurorack synthesizer case.
3. Connect the 10-pin side of the IDC power cable to the 2×5 pin header.
4. Note: This module has reverse polarity protection. Inverted installation of the power cable will not damage the module.

Channel 1

• Input (IN): Provides direct access to the channel 1 all-pass filter.
• Output (OUT): Provides the filtered signal from the channel 1 input.
• Pole Toggle: Sets the slope of the all-pass filter.
• Phase Slider: Shifts the center frequency of the filter processing the input signal.
• Phase CV Input: Bipolar control voltage input for modulating the phase slider.
• Phase CV Attenuverter: Determines depth and polarity of external modulation on phase parameter.

Channel 2

• Input (IN): Provides direct access to the second all-pass filter.
• Output (OUT): Provides the filtered signal from channel 2 input.
• Phase Slider: Shifts the center frequency of the filter processing the input signal.
• Phase CV Input: Bipolar control voltage input for modulating the phase slider.
• Phase CV Attenuverter: Determines depth and polarity of external modulation on phase parameter.
• Output Indicator: Provides LED illumination of signal amplitudes at channel 2 output.

Global Normalling
The normalling of input signals moves clockwise from channel 2 Input to channel 2 Output, suitable for mono-to-mono, mono-to-stereo, and stereo-to- stereo processing.

Patch Examples

1. Mono Phase-Shifting:
   An oscillator connected to channel 1’s Input is monitored through channel 1’s Output. Modulate the phase with a control voltage signal.

2. Serial Mono Phase-Shifting:
   An attenuated oscillator connected to channel 2’s Input is monitored through channel 2’s Output, creating a mono sum. Modulate each channel’s phase with different control voltage signals.

FAQ

1. Q: Can I use this module with other synthesizer systems?
   A: This module is designed for use with Eurorack synthesizer systems and may not be compatible with other systems without proper adapters or converters.

2. Q: How do I ensure proper power connection?
   A: Make sure to connect the IDC power cable correctly, aligning the pins and avoiding reversed polarity to prevent damage to the module.

Dual All-Pass Filter

User Manual

Description
Introducing dåpf, the first dedicated effects processor in the Instruō product line. The Instruō dåpf is a set of two analogue all-pass filters.
You might be asking yourself, “What is the point of a filter that passes everything?” All-pass filters don’t actually attenuate frequency amplitudes directly, but rather alter the phase relationship of frequencies across the spectrum. All-pass filter stages appear in the vast majority of voltage- controlled filter topologies as well as serving as a core building block within DSP.
The normalled I/O of dåpf allows for cascaded or independent use of the two all-pass filter circuits, offering everything from classic phase-shifting to psychoacoustic stereo enhancement and synthetic
Doppler effect.

Features

• Two parallel all-pass filters
• Independent attenuverters for voltage control
•  1-Pole/2-Pole configuration for channel 1
• Gascaded normalisation
• Global 1 volt per octave tracking

Installation

1. 1. Confirm that the Eurorack synthesizer system is powered off.
   2. Locate 4 HP of space in your Eurorack synthesizer case.
   3. 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.
   4. 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.
   5. Mount the Instruō dåpf in your Eurorack synthesizer case.
   6. 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 : 4 HP
• Depth : 30mm
• +12V : 60mA
• -12V : 60mA

dåpf | da:/f | (acronym) Dual All-pass Filter

Key

1. Channel 1 Input
2. Channel 1 Output
3. Pole Toggle
4. Channel 1 Phase Slider
5. Channel 1 Phase CV Input
6. Channel 1 Phase CV Attenuverter
7.  Channel 2 Input
8. Channel 2 Output
9. Channel 2 Phase Slider
10. Channel 2 Phase CV Input
11. Channel 2 Phase CV Attenuverter
12.  1V/Oct Input

Channel 1

• Input (IN): The channel 1 Input (left) provides direct access to the channel 1 all-pass filter.
• Output (OUT): The channel 1 Output (left) provides the filtered signal present at the channel 1 Input.
  • If no cable is connected to the channel 1 Output, then the signal present at the channel 1 Input is processed and passed to the channel 2 Output. Either configuration can be used for
    mono-to-mono processing.

Pole Toggle: The Pole Toggle sets the slope of the all-pass filter.

• If the toggle is in its left position, the profile of the all-pass filter is set to  – 6dB/Octave (1-Pole).
• If the toggle is in its right position, the profile of the all-pass filter is set to -12dB/Octave (2-Pole).
• Phase Slider : The Phase Slider shifts the centre frequency of the all-pass filter processing the input signal.
  •  If the Slope Toggle is set to -6dB/Octave (1-Pole), moving the Phase Slider from its minimum position to its maximum position results in a global phase shift of the input signal by 180°.
  • If the Slope Toggle is set to -12dB/Octave (2-Pole), moving the Phase Slider from its minimum position to its maximum position results in a global phase shift of the input signal by 360°.
• Phase CV Input: The Phase CV Input is a bipolar control voltage input for the Phase Slider.
  • Control voltage is summed with the Phase Slider and scaled and/or inverted by the Phase CV Attenuverter.
• Phase CV Attenuverter: The Phase CV Attenuverter determines the depth and polarity of external modulation applied to the phase parameter.

Channel 2

• Input (IN): The channel 2 Input (right) provides direct access to the second all pass filter.

• If no cable is connected to the channel 1 Input, the signal present at the channel 2 Input normals to both all-pass filter channels. In this scenario, only the corresponding phase parameter will affect the signal present at the respective channel Output. This can be used for mono-to-stereo processing.

• If no cable is connected to the channel 1 Input or channel 1 Output, then both channel’s phase parameters will affect the signal present at the channel 2 Input, creating a mono sum of both Outputs. This can be used for mono-to-mono processing with two parallel all-pass
  filter stages.

• Attenuating the input signal before connecting to the channel 2 Input is advisable to avoid clipping.

  • Output (OUT) : The channel 2 Output (right) provides the filtered signal present at the channel 2 Input.

• Phase Slider: The Phase Slider shifts the centre frequency of the all-pass filter processing he input signal.

  • Moving the Phase Slider from its minimum position to its maximum position results in a global phase shift of the input signal by 360°.

• Phase CV Input: The Phase CV Input is a bipolar control voltage input for the Phase Slider.

  • Control voltage is summed with the Phase Slider and scaled and/or inverted by the Phase CV Attenuverter.

• Phase CV Attenuverter: T he Phase CV Attenuverter determines the depth and polarity of external modulation applied to the phase parameter.

  • Output Indicato r: The Output Indicator provides LED illumination of the signal amplitudes present channel 2 Output.

Global

• 1V/Oct Input: The 1V/Oct Input is a bipolar control voltage input that is calibrated for 1 volt per octave tracking.
  • Control voltage is summed with the values set by the Phase Sliders and Phase CV Inputs.

Normalling

• The normalling of input signals moves clockwise around the panel from the channel 2 Input to the channel 2 Output.
• This normalling scheme can be used for mono-to-mono, mono-to-stereo, and stereo-to-stereo processing.

Patch Examples

• Mono Phase-Shifting:
  • Summary: An oscillator is connected to channel 1’s Input and monitored through channel 1’s Output. A control voltage signal modulates the phase.

Audio Path:

• Connect the output of a harmonically rich oscillator waveform to the channel 1 Input.
• Monitor from the channel 1 Output.
• Set the Pole Toggle to a desired setting.

Control Path:

• Connect a control voltage signal to the channel 1 Phase CV Input and set the corresponding Phase CV Attenuverter to a desired position.
• Note: If using bipolar control voltage signals, bias the corresponding Phase Slider so that negative voltage doesn’t clip the Phase CV Input.

Serial Mono Phase-Shifting:
Summary: An oscillator is attenuated and then connected to channel 2’s Input and monitored through channel 2’s Output, creating a mono sum of both channels. Two different control voltage signals modulate the phase of each channel.

Audio Path:

• Connect the output of a harmonically rich oscillator waveform to an attenuator to attenuate the amplitude of the waveform. Set the attenuator to a desired level.
• Connect the output of the attenuator to the channel 2 Input.
•  Monitor from the channel 2 Output.
•  Set the Pole Toggle to its right position to set a -12dB/Oct pole for channel 1.

Control Path:
Connect two different control voltage signals to both Phase CV Inputs and set the corresponding Phase CV Attenuverters to a desired position. Note: If using bipolar control voltage signals, bias the corresponding Phase Sliders so that negative voltage doesn’t clip the Phase CV Inputs.

Mono-to-Stereo Phase-Shifting:
Summary: An oscillator is connected to channel 2’s Input and monitored through both Outputs. Two different control voltage signals modulate the phase of each channel.

Audio Path:

• Connect the output of a harmonically rich oscillator waveform to the channel 2 Input.
• Monitor from both Outputs.
• Both outputs will need to be externally panned hard left and hard right.
• Set the Pole Toggle to its right position to set a -12dB/Oct pole for channel 1.

Control Path:

• Connect two different control voltage signals to both Phase CV Inputs and set the corresponding Phase CV Attenuverters to a desired position.
• Note: If using bipolar control voltage signals, bias the corresponding Phase Sliders so that negative voltage doesn’t clip the Phase CV Inputs.

Stereo Phase-Shifting:
Summary: Two oscillators are connected to both Inputs and monitored through both Outputs. Two different control voltage signals modulate the phase of each channel.

Audio Path:

• Connect the outputs of two harmonically rich oscillator waveforms to both Inputs.
• Monitor from both Outputs.
• Note: Both outputs will need to be externally panned hard left and hard right.
• Set the Pole Toggle to its right position to set a -12dB/Oct pole for channel 1.

Control Path:

• Connect two different control voltage signals to both Phase CV Inputs and set the corresponding Phase CV Attenuverters to a desired position.
• Note: If using bipolar control voltage signals, bias the corresponding Phase Sliders so that negative voltage doesn’t clip the Phase CV Inputs.

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.

Read User Manual Online (PDF format)

Download This Manual (PDF format)

Download this manual  >>