Instruo dåpf
Dual analogue all-pass filter for phase-shifting, stereo enhancement, and Doppler effects
4 HP Eurorack module
The dåpf is a compact dual analogue all-pass filter from Instruo. Unlike conventional filters that attenuate frequencies, all-pass filters alter the phase relationship of frequencies across the spectrum while passing all amplitudes unchanged. The two filter circuits are normalled for cascaded or independent operation, enabling classic phaser effects, psychoacoustic stereo widening, and synthetic Doppler shifts. Channel 1 offers switchable 1-Pole (-6dB/oct, 180° max) or 2-Pole (-12dB/oct, 360° max) operation, while channel 2 is fixed at 2-Pole. A global 1V/oct input tracks both channels for pitch-synchronised phase processing.
Features
- Two parallel analogue all-pass filter circuits
- Independent attenuverters for bipolar CV modulation of each channel phase
- Switchable 1-Pole/2-Pole configuration for channel 1 (-6dB/oct or -12dB/oct)
- Channel 2 fixed at 2-Pole (-12dB/oct, 360 degree range)
- Cascaded I/O normalling for mono-to-mono, mono-to-stereo, and stereo processing
- Global 1V/oct tracking input summed with both phase sliders
- Output LED indicator for channel 2 signal amplitude
- 4HP, 30mm deep, 60mA per rail
Controls & Jacks (13)
- Ch 1 In — Audio input for channel 1 all-pass filter. If no cable is connected to Ch 2 In, the signal here normals to both channels.
- Ch 1 Out — Filtered output from channel 1. If unplugged, channel 1 output is passed to channel 2 for mono-to-mono processing.
- Ch 1 Phase — Sets the centre frequency of the channel 1 all-pass filter. In 1-Pole mode, sweeps 0-180 degrees; in 2-Pole mode, sweeps 0-360 degrees.
- Ch 1 Phase CV In — Bipolar CV input for modulating the channel 1 phase parameter. Summed with Ch 1 Phase slider and scaled by Ch 1 Phase CV Atten.
- Ch 1 Phase CV Atten — Attenuverter controlling the depth and polarity of external CV modulation applied to channel 1 phase.
- Pole — Selects 1-Pole (-6dB/oct, 180 degree max shift) or 2-Pole (-12dB/oct, 360 degree max shift) for channel 1.
- Ch 2 In — Audio input for channel 2 all-pass filter. If unplugged, the signal normals from channel 1 for cascaded or mono-to-stereo use.
- Ch 2 Out — Filtered output from channel 2.
- Ch 2 Phase — Sets the centre frequency of the channel 2 all-pass filter. Sweeps the full 0-360 degree range.
- Ch 2 Phase CV In — Bipolar CV input for modulating the channel 2 phase parameter. Summed with Ch 2 Phase slider and scaled by Ch 2 Phase CV Atten.
- Ch 2 Phase CV Atten — Attenuverter controlling the depth and polarity of external CV modulation applied to channel 2 phase.
- Output Indicator — LED indicating signal amplitude at channel 2 output.
- 1V/Oct In — Bipolar 1V/octave tracking input summed with both phase sliders and CV inputs for global pitch-tracked phase control.
How-To Guides
- Mono Phase-Shifting
- Mono to Stereo Phase-Shifting
- Stereo Phase-Shifting
Explore the interactive dåpf panel on BleepDex — tap any control to learn what it does.
