MATRIXSYNTH: Instruō Introduces dåpf Dual All-Pass Filter Effects Processor Eurorack Module

Tuesday, February 20, 2024

Instruō Introduces dåpf Dual All-Pass Filter Effects Processor Eurorack Module

via Instruō

"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.

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

Instruō - dåpf Overview

video upload by Instruō

"This video is long... But the second half is very much optional expansion and deep dive into some theory of all-pass filters.
The first few examples are much quicker, more practical examples of dåpf patched.
Thanks for watching :)"
00:00:00 Instruōduction
00:03:24 Overview | Stereo Enhancement
00:04:19 Stereo Enhancement - Subtractive patch sound source
00:04:55 Stereo Enhancement - Traditional stereo panning
00:06:13 Stereo Enhancement - Spectrally transparent waveshaping
00:07:22 Stereo Enhancement - dåpf inputs/outputs
00:09:42 Stereo Enhancement - Controls and CV inputs
00:10:14 Stereo Enhancement - 6dB/12dB pole switch
00:11:18 Stereo Enhancement - Mono to Stereo patching
00:15:41 Stereo Enhancement - Static phase shift
00:17:32 Stereo Enhancement - Level 1: modulation
00:19:40 Stereo Enhancement - Level 2: modulation + waveshaping
00:25:02 Stereo Enhancement - Level 3: modulation + timbre
00:27:50 Vibrato Everything
00:28:17 Vibrato Everything - What is vibrato?
00:29:35 Vibrato Everything - Non-FM vibrato
00:30:22 Vibrato Everything - (tangent: sine phase)
00:31:34 Vibrato Everything - (tangent: sine spatialisation)
00:32:37 Vibrato Everything - Non-FM vibrato (sine wave)
00:34:11 Vibrato Everything - Non-FM vibrato (sawtooth wave)
00:38:42 Vibrato Everything - Non-FM vibrato (complex audio)
00:40:46 Vibrato Everything - Non-FM... FM? ...PM! (Phase Modulation)
00:43:47 Feedback Processing |"Doppler"
00:44:33 Feedback Processing |"Doppler" - Lúbadh feedback patch
00:46:38 Feedback Processing |"Doppler" - Doppler shift description
00:48:08 Feedback Processing |"Doppler" - Doppler dåpf 1pole/2-pole
00:49:20 Feedback Processing |"Doppler" - Doppler dåpf 3-pole/-4pole
00:51:28 Feedback Processing |"Doppler" - Doppler dåpf in stereo!
00:52:02 Feedback Processing |"Doppler" - Delay feedback
00:54:54 Feedback Processing |"Doppler" - Audio rate modulation
00:56:32 Building a phaser - Deep dive into all-pass filters
00:58:44 Building a phaser - Phase shift of a fundamental
00:59:41 Building a phaser - Quadrature: sine | cosine
01:00:43 Building a phaser - Drawing perfect circles
01:01:41 Building a phaser - Drawing (non-)perfect circles
01:02:16 Building a phaser - Frequency dependent phase shift
01:04:22 Building a phaser - 1V/octave tracking
01:07:40 Building a phaser - More than one sine wave
01:08:58 Building a phaser - The harmonic overtone series
01:10:19 Building a phaser - Sawtooth wave low-pass filtered (reference)
01:11:15 Building a phaser - Phase shifting harmonic overtones
01:15:42 Building a phaser - Inside a phaser
01:18:00 Building a phaser - Stereo Phaser
01:22:19 Building a phaser - uPhaser Befaco FXBoy
01:23:46 Building filters - Any-pass filter?
01:25:05 Building filters - RC low-pass filter
01:26:03 Building filters - Spectral cancellation principles
01:28:35 Building filters - APF to LPF
01:30:10 Building filters - APF to HPF
01:32:03 Building filters - Parallel dual all-pass filters
01:37:41 Building filters - Resonant filters"

And a video from Divkid:

Wow! I didn't know All Pass Filters could do this // 3 Patches with dapf from Instruo
video upload by DivKid

"I'm always striving to learn and explore with sound and music and dapf (the new Eurorack module from Instruo) certainly brought a big slap of school day into DivKid HQ. I was aware of all pass filters, getting past the funny idea that "all" frequencies pass (so what's the point?) and knowing they were use for phase shifts. What I didn't know is how core and important to filter topologies they were and how creatively useful they could be.

Some exploring later and here we are, with 3 patches that really show the power of phase manipulation. While dapf makes a fantastically chewy phaser FX unit I didn't expect it would be such a great stereo expander for a single VCO nor did I know I could be MUSICAL and totally analogue 3 operator FM/PM (like the digital Yamaha DX and Casio CZ phase/FM methods) synth."

No comments:

Post a Comment

Do not insult people. Do not ask if listings are still available. Click through auction links to check yourself. Posts and pics remain for historical purposes only. To reduce spam, comments for posts older than one week are not displayed until approved, usually same day.


Switched On Make Synthesizer Evolution Vintage Synthesizers Creating Sound Fundlementals of Synthesizer Programming Kraftwerk

© Matrixsynth - All posts are presented here for informative, historical and educative purposes as applicable within fair use.
MATRIXSYNTH is supported by affiliate links that use cookies to track clickthroughs and sales. See the privacy policy for details.