Rob Hordijk Phaser Filter: Difference between revisions

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[[File:Hordijk_pf.png|thumb|right|200px]]The 2U wide '''Rob Hordijk Phaser Filter''' module combines 5 allpass poles with three lowpass poles in one module. The five allpass poles are configured as a phaser with positive feedback resonance control, creating two resonant peaks when opened. Then a crossfade knob fades between the input and the output of the phaser and this crossfade mix is the input signal into the lowpass filter. At the end of the allpass chain before the crossfader is a phaser monitor output. The lowpass section has a cutoff slope of -18dB/Oct and its own resonance control.
[[File:Hordijk pf.png|thumb|right|200px]]The 2U wide '''Rob Hordijk Phaser Filter''' module combines 5 allpass poles with three lowpass poles in one module. The five allpass poles are configured as a phaser with positive feedback resonance control, creating two resonant peaks when opened. Then a crossfade knob fades between the input and the output of the phaser and this crossfade mix is the input signal into the lowpass filter. At the end of the allpass chain before the crossfader is a phaser monitor output. The lowpass section has a cutoff slope of -18&nbsp;dB/Oct and its own resonance control.<ref name="rh">Rob Hordijk</ref>


[[File:Hordijk_pf_fc.png|thumb|right|200px|The Phaser Filter flowchart]]Both the phaser section and the lowpass section have a 1V/Oct control law. The phaser has one modulation input and if it is not connected the audio input signal is used as the modulation signal. This allows for dynamic waveshaping of the input signal on the time axis without detuning to signal.
[[File:Hordijk pf fc.png|thumb|right|200px|The Phaser Filter flowchart]]Both the phaser section and the lowpass section have a 1V/Oct control law. The phaser has one modulation input and if it is not connected the audio input signal is used as the modulation signal. This allows for dynamic waveshaping of the input signal on the time axis without detuning to signal.<ref name="rh" />


The filter section has two modulation inputs, if the first is not connected the filter audio input signal is used to modulate the filter cutoff, allowing for even more dynamic waveshaping just like in the phaser section. If the second modulation input is not used it uses a signal from halfway the lowpass poles to self-modulate, thus producing all-harmonic distortion on the resonance peak when the resonance is set fairly high.
The filter section has two modulation inputs, if the first is not connected the filter audio input signal is used to modulate the filter cutoff, allowing for even more dynamic waveshaping just like in the phaser section. If the second modulation input is not used it uses a signal from halfway the lowpass poles to self-modulate, thus producing all-harmonic distortion on the resonance peak when the resonance is set fairly high.<ref name="rh" />


When the 1V/Oct input jack for the filter is not used it inherits the signal from the phaser section 1V/Oct input jack.
When the 1V/Oct input jack for the filter is not used it inherits the signal from the phaser section 1V/Oct input jack.<ref name="rh" />


Both phaser and filter can sweep over a range of roughly 18 octaves and can be modulated up to really high audio rates. In this last case FM-type and ring-modulator-type effects occur, but with much more timbral control than traditional ring-modulators. E.g. when the outputs of two OSC HRM modules, set to sinewave output and tuned in some interval, are mixed and routed into the filter just slight amounts of the internal modulation on either the phaser or the filter will start to produce ‘undertones’ and ‘overtones’ that are sum and difference frequencies of the interval. This exemplifies the idea behind the Phaser Filter architecture, to not only take material away like a normal filter does but to also produce new material not present in the input signal and combine the both to create a vast range of possible timbres.
Both phaser and filter can sweep over a range of roughly 18 octaves and can be modulated up to really high audio rates. In this last case FM-type and ring-modulator-type effects occur, but with much more timbral control than traditional ring-modulators. E.g. when the outputs of two OSC HRM modules, set to sinewave output and tuned in some interval, are mixed and routed into the filter just slight amounts of the internal modulation on either the phaser or the filter will start to produce ‘undertones’ and ‘overtones’ that are sum and difference frequencies of the interval. This exemplifies the idea behind the Phaser Filter architecture, to not only take material away like a normal filter does but to also produce new material not present in the input signal and combine the both to create a vast range of possible timbres.<ref name="rh" />


The Phaser Filter is no longer produced, it was sort of a prototype and only 2 or 3 units were sold.<ref>Muff Wiggler forum:[http://www.muffwiggler.com/forum/viewtopic.php?p=1637899&sid=0a73e529ded24288f653d5fb0fc1a578 Hello Hordijk System]</ref>
The Phaser Filter is no longer produced, it was sort of a prototype and only 2 or 3 units were sold.<ref>Mod Wiggler forum:[https://www.modwiggler.com/forum/viewtopic.php?p=1637899&sid=0a73e529ded24288f653d5fb0fc1a578 Hello Hordijk System]</ref>


==References==
== References ==
{{From Mod Wiggler Wiki|Rob Hordijk Designs}}
{{reflist}}
{{reflist}}


==External links==
== External links ==
*[https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/574459-rob-hordijk-phaser-filter-audio-clips.html Rob Hordijk Phaser Filter audio clips]
* [https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/574459-rob-hordijk-phaser-filter-audio-clips.html Rob Hordijk Phaser Filter audio clips]


[[Category:Original Rob Hordijk Design]]
[[Category:Original Rob Hordijk Design]]

Latest revision as of 18:09, 24 April 2021

The 2U wide Rob Hordijk Phaser Filter module combines 5 allpass poles with three lowpass poles in one module. The five allpass poles are configured as a phaser with positive feedback resonance control, creating two resonant peaks when opened. Then a crossfade knob fades between the input and the output of the phaser and this crossfade mix is the input signal into the lowpass filter. At the end of the allpass chain before the crossfader is a phaser monitor output. The lowpass section has a cutoff slope of -18 dB/Oct and its own resonance control.[1]

The Phaser Filter flowchart

Both the phaser section and the lowpass section have a 1V/Oct control law. The phaser has one modulation input and if it is not connected the audio input signal is used as the modulation signal. This allows for dynamic waveshaping of the input signal on the time axis without detuning to signal.[1]

The filter section has two modulation inputs, if the first is not connected the filter audio input signal is used to modulate the filter cutoff, allowing for even more dynamic waveshaping just like in the phaser section. If the second modulation input is not used it uses a signal from halfway the lowpass poles to self-modulate, thus producing all-harmonic distortion on the resonance peak when the resonance is set fairly high.[1]

When the 1V/Oct input jack for the filter is not used it inherits the signal from the phaser section 1V/Oct input jack.[1]

Both phaser and filter can sweep over a range of roughly 18 octaves and can be modulated up to really high audio rates. In this last case FM-type and ring-modulator-type effects occur, but with much more timbral control than traditional ring-modulators. E.g. when the outputs of two OSC HRM modules, set to sinewave output and tuned in some interval, are mixed and routed into the filter just slight amounts of the internal modulation on either the phaser or the filter will start to produce ‘undertones’ and ‘overtones’ that are sum and difference frequencies of the interval. This exemplifies the idea behind the Phaser Filter architecture, to not only take material away like a normal filter does but to also produce new material not present in the input signal and combine the both to create a vast range of possible timbres.[1]

The Phaser Filter is no longer produced, it was sort of a prototype and only 2 or 3 units were sold.[2]

References

This page uses Creative Commons Licensed content from Mod Wiggler Wiki:Rob Hordijk Designs (View authors).

  1. ^ a b c d e Rob Hordijk
  2. ^ Mod Wiggler forum:Hello Hordijk System

External links