INSTRUo Dual All Pass Filter User Manual
- May 15, 2024
- INSTRUO
Table of Contents
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
- Confirm that the Eurorack synthesizer system is powered off.
- Locate 4 HP of space in your Eurorack synthesizer case.
- Connect the 10-pin side of the IDC power cable to the 2×5 pin header.
- 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
-
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. -
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
-
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. -
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. 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
- Channel 1 Input
- Channel 1 Output
- Pole Toggle
- Channel 1 Phase Slider
- Channel 1 Phase CV Input
- Channel 1 Phase CV Attenuverter
- Channel 2 Input
- Channel 2 Output
- Channel 2 Phase Slider
- Channel 2 Phase CV Input
- Channel 2 Phase CV Attenuverter
- 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.
- 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
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.
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