FiltherManual

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Filther User Manual v0.2

Filther wouldn’t be here without the work of many individuals, to whom I own thanks! While some filters and effects were modelled by me, many also came from literature sources.

Filter attribution:

Special thanks also goes out to everyone who has reported bugs and provided ideas to me. This list includes, but it is not limited to: Eliseat, Bri1, FoxAsteria, EpicSounds, TonE, daxliniere, JamesPeters, kneipp123, jrengmusic, mawi, vdubreeze, Sju, nitsuj, Steve K, Spkka, Kom and of course my wife!

And of course Cockos Inc. for developing JSFX.

About Filther

Before you lies the manual to my latest experiment: Filther. While its interface can admittedly look daunting at first, you’d be surprised at the flexibility at your fingertips. So, to try and convince you that the effort of getting into this baby is worth it (despite its somewhat high CPU cost), here’s a rundown of what it can offer:

Installation

The easiest way to install Filther and be kept up to date with updates is to add the following repository to your Reapack: https://raw.githubusercontent.com/JoepVanlier/JSFX/master/index.xml

You can find more information on how to do this here: https://reapack.com/user-guide#import-repositories

Alternatively, you can extract the zip-file you downloaded and place it in your JSFX effects folder.

Overview

Filther’s interface can be daunting at first, as it may feel like you’re looking at the HUD of a cockpit (someone else’s words, not mine!). But rest assured, it is possible to work with this thing and sometimes, it can be surprisingly satisfying. Let’s start, shall we?

When opening Filther for the first time, you are greeted by the following UI:

Overview

Filther is layed out in a few different sections. Try and locate the following sections in the image above: Waveshaper, Spectrum, Envelopes, Control Strip (with Master, Filter A, Filter B, Routing, Dynamics, LFO, Feedback, Inputs/Dynamics Section).

The manual is built up as follows. First, we go through the basics and guide you through the different elements that Filther has. Then we cover how to dynamically link the various elements to generate aggressive modulating sounds. This manual is best read twice, as some concepts mentioned briefly in earlier sections return in more detail later.

UI Controls

Sliders

The backbone of Filther is a whole bunch of sliders. They look simple at first, but they have a hidden dark side to them. All of these sliders can be automated and linked up with various modulators in Filther.

Master

The basic controls are mostly what you’d expect. Sliders can be dragged with the left mouse button or adjusted via the scrollwheel. More precise motions can be made by holding CTRL, SHIFT or both. Double click resets a slider.

Modulations are essential to making interesting moving sounds with Filther and for this reason, most sliders allow a modulation range to be set. These modulation ranges can be set using the outer mouse button.

When activated, all applied modulators use the same set range. This is best explained with a short example. For instance, when two envelopes (E1 and E2) are active for one parameter, the resulting modulation range is given by ModRange * (E1+E2)/2.

The only exception to this rule is the LFO, which functions according to the LFO range, which is proportional to the modulation range, but which is added on top of the other modulators rather than averaged with them. In particular this last rule takes some getting used to.

A dropdown menu can be navigated by clicking them with the left mouse button, followed by the selection of an option. After a dropdown is selected, one can leaf through the different options using the up and down arrow keys. Alternatively, one can navigate the options by using the mousewheel. Note that some options listed may be more experimental than others (more dangerous). These options are listed in red and will be skipped when navigating with arrow keys or mouse wheel. It is also possible to blacklist other filters, by clicking them with the right mouse button. The blacklisted list will be stored in saved presets.

Master Panel

Global properties can be found and controlled form the Master Panel located on the Control Strip.

Master

Here we find the following global controls:

Since Filther is a non-linear plugin, it responds differently to different levels of gain. While most of the non-linear filter models smoothly saturate, the waveshaper can respond dramatically different depending on how much input gain is provided.

Waveshaper

Filther began its life as a waveshaper. This is also the reason that the waveshaper is so prominently placed in the UI. Filther supports saturating soft clipping as well as drawing custom voltage curves using a spline. These options can be selected from the Waveshaper Selection dropdown menu. For the simpler filters, the distortion is simply applied before the filtering stage, but for some the filter is located in the filter itself. In these cases, the distortion is either applied on the delayed or during solving the implicit equations for the supplied zero delay feedback filters (ZDF).

Waveshaper

When looking at the waveshaping module in Filther, we notice two windows. One termed negative, the other called positive. These refer to the negative and positive parts of the audio waveform. Positive values are shaped according to the curve in the positive window, while negative parts are shaped according to the negative window.

The drawn waveshaping curve maps an input voltage to an output voltage. For each polarity, the current peak Input Voltage is shown in red, below each graph. This peak value can be used to tune the input gain of the plugin, to make full use of the waveshaping functions. The Output Voltage can be seen on the vertical axes and is drawn in blue.

When set to spline mode, user defined distortion curves can be drawn by moving control nodes around. New nodes can be created by pressing the right mouse button anywhere inside the waveshaping window. They can also be deleted by clicking them with the right mouse button. A curve can be transferred from the positive voltage map to the negative voltage map using the Curve Transfer buttons indicated in the figure.

Hint: Waveshaping introduces higher harmonics and can cause aliasing. Aliasing refers to frequencies above Nyquist that wrap back into the spectrum and result in peaks that are inharmonic with respect to the source material. To mitigate this, Filther allows oversampling (see also: Oversampling).

Spectrum

Filter continuously shows you the input (shaded) and output (line) frequency spectrum as well as the filter characteristics (where sensible).

Spectrum

Filters

Filther contains two filter modules which can be fully automated by dynamics and LFO. Each filter can be bypassed by clicking the Bypass button. Again, we see in the group header that various modulations can be enabled or disabled. In both Filter sections modulation by a specific modulator can be toggled using the left mouse button. More fine grained control can be achieved using the right mouse button, which allows you to select either cutoff or resonance to be modulated by that specific modulator.

Filtertypes

As shown in the image, the available modulators are:

Filters can be chosen from the dropdown menu denoted by Filter Type in the figure. Filther contains a large variety of filters to choose from, each with their own advantages and drawbacks. Most of the filters behave non-ideal and are intended for creative purposes rather than linearity.

Filters

Note: Not all filters are stable for all combinations of resonance and waveshaping. Using very sharp transitions in the spline waveshaper can result in filter instability for the filters where waveshaping is part of the filter. Filters which are more dangerous than others are marked in red.

Special filter modes

Filter A has some special filter modes which can be used for stereo widening or processing samples differently. These can be selected from the Filter Mode dropdown. Note that some of these modes are highly experimental and may misbehave (the ones that have the potential to misbehave are colored in red).

Key tracking

Keytracking can be used to track the frequency of incoming MIDI notes. This helps preserve timbre when notes of varying frequency are coming in. This is particularly important for ring modulation filters, which will otherwise sound terrible.

Key tracking can be enabled by enabling the KEY symbol above each filter. Note that you may have to adjust the cutoff accordingly after enabling keytracking. For normal frequency following, keep keytracking scaling in the Master panel set to one.

Note: When setting a filter up for keytracking, it can help to just loop a single MIDI note, so you can hone in on the cutoff better.

Pitch follow

Pitch following is similar to keytracking in the sense that it attempts to follow the pitch of incoming notes. In contrast to keytracking, pitch following works on audio data rather than MIDI data. Enabling pitch following for any of the filters results in a detected pitch being displayed in the spectrum.

PitchDetect

Modulation filters

Modulation filters are special in the sense that they require accurate tuning to sound good. To help tune modulation filters, a few helper lines are drawn on the spectrum. For best results, try and match up the harmonics of the modulator with the harmonics of the input sound while having keytracking enabled.

Harmonics

Routing

Filther supports six routing modes which can be chosen in the routing submenu in the control strip.

Routing

The different routing modes available are:

Note: The morph mode allows you to modulate the interpolation between Filter A and Filter B

Note: Using morph routing means you can only use a maximum of 7 nodes for the spline waveshaper.

Dynamics

This is where the fun begins, but arguably also the most tricky part of controlling Filther and making it do what you want. Filther supports modulation of various settings via audio, MIDI or modulation wheel and it is exactly these modulations that can be used to make sounds move.

Dynamics can be monitored in the dynamics window (shown on the left). Here you will typically see the input RMS (red curve), output RMS (purple curve) and most importantly, the dynamic variable (yellow curve). This dynamic variable and its position along the vertical axis determines the current modulation applied by any active DYN modulator. Zooming into the panel can be done by means of clicking with the left mouse button and dragging.

Enabling the button SHAPER in the dynamics section to enable modulation of the waveshaper by the dynamic variable. When enabled, Filther will interpolate between the non-waveshaped and waveshaped voltage input/output characteristic (1 being the fully waveshaped version).

Dynamics

Depending on which mode you are currently using, the vertical position of the dynamic variable is determined by different factors. Additionally, you will also be presented with different Dynamics panels depending on the mode you are in. Let’s go over the different modes:

Audio modes

These modes are driven by audio signals coming into Filther. They are Driven RMS which means Filther is listening to the RMS after the Pre-Gain stage. Pre-Gain RMS, which means it is listening to the incoming signal on channel 1 and 2 and Sidechain, which results in listening to channel 3 and 4. Note that when using the side chain mode, the displayed in signal also shows that of the side chain. The audio modes come in two flavors:

MIDI modes

In these modes, the dynamic curve is driven by MIDI input signals. Whereas MIDI only uses the note on and off information MIDI Velocity also makes use of the velocity information when determining the maximum amplitude of the dynamic variables.

Modwheel mode

In this mode the dynamic variable is directly controlled via the modulation wheel. Since modulation wheel data is rather coarse, smoothing options become available once this mode is selected. One is linear, the other is exponential.

Note: All of the sliders involving time have optional multipliers, which can be set for longer attack, hold and decay times.

LFO

Filter sports a Low Frequency Oscillator (LFO) for modulating other parameters. Most LFO variables are self explanatory. When enabled, the MIDI button makes sure that any incoming MIDI note triggers a reset of the LFO. Tempo changes the time axis to a tempo synchronized axis and Center centers the LFO around the slider value, rather than setting its maximal extent to the slider value (without it, it moves in the direction of the modulation range).

LFO

Whereas all other dynamic modulators in Filther (envelopes and dynamics) are averaged to work out to one dynamic modulation, the LFO is treated separately. The modulation strength of the LFO is set in the LFO panel with the parameter Modulation Range. While it will still be proportional to the range set on the modulation target, there is an extra level of control with respect to how much modulation is happening at any given time.

One last feature which may be important for some filter/LFO combo’s is LFO smoothing. When enabled, sharp transients generated when the LFO resets or suddenly changes shape are smoothed out to avoid annoying artefacts. In can be enabled by clicking the little box inside the LFO preview.

Envelopes

Envelopes can be used to add some extra dynamics to your sounds. They can be used as modulation sources alongside other sources. When TRIG is enabled, an envelope will restart playback whenever a MIDI note is pressed. Once it gets to the hold loop it will loop until the MIDI note is released. Note that when TRIG is not active, the envelope will loop indefinitely and can be used as an alternative, more customizable LFO.

Envelopes

To add nodes to the envelope click the curve with the right mouse button. To remove nodes, click them with the right mouse button. Nodes can be dragged with the left mouse button. The scrollwheel can be used to zoom into the envelope, while dragging results in panning over the envelope. The duration of the envelope can be set by dragging the bottom slider. The shape of an individual envelope section can be modified by either double clicking on the section of envelope to be changed or by holding ALT and dragging the mouse while holding the left mouse button. Finally, shapes for the entire envelope can be modified simultaneously by adding the modifier CTRL.

Feedback section

There is an additional feedback section, which can be activated. Feedback can be used to fatten up filters and in some cases regain control of the resonance. If you want some fatness/resonance fighting, keep the delay firmly placed at zero. The feedback delay chain has the exact opposite polarity of the resonance in most chains, so in this mode, it will fight with the resonance to sort of choke in on itself. This can make the resonance less ringey, more chunky and a lot more pleasant to listen to. For a good example of this effect, set up a diode ladder or ms-20 with a lot of resonance. Then dial in the feedback with a feedback time of zero. You’ll notice that the screechyness of the resonance goes down, giving way to a more chunky growliness.

Feedback

For phasey effects, use feedback with larger delays. Note however that then you’re in the danger zone, because once resonance starts boosting resonance, things get real dicey. I would always recommend playing with this only if you have Automatic Gain Control (AGC) on.

Note: Also note that using feedback, reduces the maximum number of spline nodes by two.

Automatic Gain Control

When tweaking, enable Automatic Gain Control to protect your ears from resonance issues. This rescales the volume so that the RMS value post filter is the same as the input level (meaning that you can leave the post fader at 0 dB). You can transfer the estimated gain to the post-gain fader with the outer mouse once you’ve honed in on a preset you like.

Oversampling

Filther supports oversampling. Oversampling can be useful when an effect introduces many harmonics due to non-linear distortion. These harmonics then result in aliasing, which is the result of frequencies folding back into the spectrum. Typically, most people do not like the sort of aliasing, as the newly introduced frequencies tend to be inharmonic with the ones already present.

Oversampling runs the waveshaper and simulates the filters at a higher samplerate. Subsequently aliasing is reduced by lowpassing the result before sampling down back to the normal sample rate.

Note that oversampling incurs significantly more CPU and that not all sounds need an oversampling solution. In particular sounds which are mostly concentrated in the low end, with very little presence in the higher frequencies may not need oversampling at all. For basslines, large amounts of oversampling are usually unnecessary and only drive up the CPU cost.

Note that the oversampling filters used in Filther are relatively coarse and may reduce some of the higher frequencies.

Note: Some of the filters in filther require a minimal amount of oversampling for stability. These filters will always force the oversampling to be where they need it to be.

Note: Both FIR and IIR upsampling/downsampling are provided. Whereas FIR filtering causes less phase distortion, it is more costly.

List of filters

FilterList

Filters are categorized by type, typically starting with the linearized versions of the filters first, followed by the more CPU intensive, but also more interesting, non-linear versions.

Type Filter Description
LP Linear SVF 2-pole zero delay feedback filter based on Andy Simper’s (Cytomic) SVF filter algorithms. This is the go-to filter if you want a transparent non-saturating lowpass.
LP RC-C State space filter. This filter does not use internal waveshaping and the output of the filter is waveshaped instead. Prone to resonating quite fiercely.
LP Kr0g MS20 linear A linearized version of the 2-pole MS-20 emulation. Sounds relatively transparent. Note that this filter doesn’t saturate or self-oscillate in the way the non-linear emulation would. The computational cost is much lower however.
LP SSM 2020 linear Linearized 4-pole SSM2020 emulation. Note that this filter doesn’t saturate or self-oscillate in the way the non-linear emulation would. The computational cost is much lower however. The waveshaper is applied to the output and can be used to tame or excite the output.
LP CEM 3389 linear Linearized 4-pole CEM 3389 emulation. Note that this filter doesn’t saturate or self-oscillate in the way the non-linear emulation does. The computational cost is much lower however. The waveshaper is applied to the output.
LP Waspey linear Linearized approximation of the waspey.
LP Kr0g MS20 NL II MS-20 emulation with non-linearity. This thing sounds great when overdriven, especially without waveshaper. The non-linear elements consist of integrators that saturate at each stage, and a nice diode clipper in the feedback. It can sound raw, yet clean, if that makes sense.
LP Kr0g MS20 NL MS-20 emulation with non-linearity. This thing sounds great when overdriven, especially without waveshaper. The non-linear elements consist of integrators that saturate at each stage, and a nice diode clipper in the feedback. It can sound raw, yet clean, if that makes sense. This version contains an atan instead of the correct tanh term in the integrator and the maximal frequency doesn’t go as high, but it’s sound was also pleasant so I decided to keep it as an alternative option.
LP Diode Ladder This filter was based on a model by Dominique Wurtz which modelled the 303 diode ladder. The only modification is that rather than input clipping, the waveshaper is used. This filter pairs well with a high resonance and large negative feedback. It also loves being driven.
LP Expensive Moog This filter is based on the paper Modeling and measuring a Moog voltage-controlled filter by Paschou et al. This filter requires 2x upsampling to remain stable. This version is more stable than the cheap version, but still be careful. High gain with high resonance can lead to extreme resonance peaks.
LP Cheap Moog Based on the paper Modeling and measuring a Moog voltage-controlled filter by Paschou et al. Note that at a minimum, this filter requires 2x upsampling to remain stable. Higher values will bring in higher quality as the non-linearity makes it sensitive to aliasing problems. This version does not correctly compute the Jacobian and omits several terms which are estimated to be small, which makes it faster, but more unstable. This can lead to stability problems with high frequencies, but works fine for low frequency inputs.
LP SVF w/shaped res State Variable Filter that lowpasses the signal twice. Once with and once without resonance. Subsequently it waveshapes the version with resonance minus the version without and adds the waveshaped resonance to the no resonance lowpass mix. Gives a lot of control over the bite of the resonance.
LP Rezzy Rezzy came about after an afternoon of screwing around with non-linearities in the feedback mechanism of the MS-20 lowpass filter. It can sound quite bitey and raw. At high resonances, problematic overtones can occur.
LP SSM 2020 NL 4-pole SSM-2020 emulation with non-linearity (tanh) in the model. The waveshaper is applied to the output. Note that at high resonances, this one can go slightly out of tune because of the slew rate in the feedback.
LP SSM 2020 NL (app) 4-pole SSM-2020 emulation with non-linearity (cheaper tanh) in the model. The waveshaper is applied to the output and can be used to tame the output. Note that at high resonances, this one can go slightly out of tune because of the slew rate in the feedback.
LP Combed Resonance Signal is lowpassed twice with and without resonance. Resonance is lifted by differencing the signal, this resonance is mixed with a delayed copy of itself before being added to the signal. Waveshaper is applied after the filter. The result is a resonant filter with some subtle hints of comb filtering.
LP CEM 3389 NL 4-pole CEM 3389 emulation with non-linearity (tanh) in the model. The waveshaper is applied to the output and can be used to tame or excite the output.
LP Voodoo This one is a meanie. It filters the signal with and without resonance, computes the difference, amplifies it, saturates it and then adds it to a moving average that gets added to the signal. The result is then waveshaped. Yum.
LP LP Junk This one is fickle. It filters the signal with and without resonance, computes the difference, amplifies it, saturates it and then adds it back to the signal. The result is then waveshaped. Yum.
LP Waspey NL CPU intensive approximation of the wasp filter.
LP Karlsen Ladder III This filter is based on a 303 diode ladder. The filter uses the waveshaper as non/ideal part rather than just clipping. Note that this filter doesn’t completely maintain its tone when using different levels of supersampling.
LP Karlsen Ladder IIIs This filter combines the 303 diode ladder filter with a fixed shelf filter. The filter uses the waveshaper as non/ideal part rather than just clipping. Note that this filter doesn’t completely maintain its tone when using different levels of supersampling.
LP Waveshaped LP This filter consists of two first order low-pass filters. The difference in filter outputs is distorted through the waveshaper and fed back to give a resonant peak. The output is then subsequently distorted again. This filter can get very mean depending on the waveshaping curve. Be careful! Note that this filter forces oversampling to be at least 2x.
LP FM Feedback Non-linear MS-20 but with the feedback signal FM modulated. The result is that it behaves almost like a shelf filter.
LP FM-ish 2 This filter uses the input signal as modulation source for the cutoff of a linearized MS-20. Can be quite unpredictable.
LP Narsty This is a relatively nasty and experimental filter. It’s a combination of three filters with varying interacting resonances. No guarantees that this thing won´t blow up in your face. Exclusively meant for basses. Note that one rather undesirable property of this filter is that it does not maintain its character when changing the sampling rate.
LP Broken feedback A circuit bended version of the non-linear Waspey with a modification in the feedback path.
LP Everything is a saw Weird filter that tends to convert most things to saw like waveforms. Based on biasing the wasp emulation severely. It can work pretty nicely with basses and high resonance, but be careful, it is pretty unpredictable.
     
BP Linear SVF Zero delay feedback filter based on Andy Simper’s (Cytomic) SVF filter algorithms. Good for transparent filtering.
BP Kr0g MS20 linear A linearized version of the 2-pole MS-20 emulation. Sounds relatively transparent. Note that this filter doesn’t saturate or self-oscillate in the way the non-linear emulation would. The computational cost is much lower however.
BP Kr0g MS20 NL II MS-20 emulation with non-linearity. This thing sounds great when overdriven, especially without waveshaper. The non-linear elements consist of integrators that saturate at each stage, and a nice diode clipper in the feedback. It can sound raw, yet clean, if that makes sense.
BP Kr0g MS20 NL MS-20 emulation with non-linearity. This thing sounds great when overdriven, especially without waveshaper. The non-linear elements consist of integrators that saturate at each stage, and a nice diode clipper in the feedback. It can sound raw, yet clean, if that makes sense. This version contains an atan instead of the correct tanh term in the integrator and the maximal frequency doesn’t go as high, but it’s sound was also pleasant so I decided to keep it as an alternative option.
BP Combed Resonance Signal is lowpassed twice with and without resonance. Resonance is lifted by differencing the signal, this resonance is amplified, saturated and mixed with a delayed copy of itself before being added to the signal. Waveshaper is applied after the filter. The result is a resonant filter with some subtle hints of comb filtering.
BP Waspey NL CPU intensive approximation of the wasp filter.
BP Waveshaped BP This is a waveshaped bandpass filter. Sort of. The difference in filter outputs is distorted through the waveshaper and fed back to give a resonant peak. The output is then subsequently distorted again. Stability can be enhanced by oversampling. Note that this filter forces oversampling to be at least 2x.
     
HP Linear SVF Zero delay feedback filter based on Andy Simper’s (Cytomic) SVF filter algorithms. Good for transparent filtering.
HP Kr0g MS20 linear A linearized version of the MS-20 emulation. Sounds relatively transparent. Note that this filter doesn’t saturate or self-oscillate in the way the non-linear emulation would. The computational cost is much lower however.
HP Kr0g MS20 NL II MS-20 emulation with non-linearity. This thing sounds great when overdriven, especially without waveshaper. The non-linear elements consist of integrators that saturate at each stage, and a nice diode clipper in the feedback. It can sound raw, yet clean, if that makes sense.
HP Kr0g MS20 NL MS-20 emulation with non-linearity. This thing sounds great when overdriven, especially without waveshaper. The non-linear elements consist of integrators that saturate at each stage, and a nice diode clipper in the feedback. It can sound raw, yet clean, if that makes sense. This version contains an atan instead of the correct tanh term in the integrator and the maximal frequency doesn’t go as high, but it’s sound was also pleasant so I decided to keep it as an alternative option.
HP Waveshaped HP This is a waveshaped highpass filter. The difference in filter outputs is distorted through the waveshaper and fed back to give a resonant peak. The output is then subsequently distorted again. Stability can be enhanced by oversampling. Note that this filter forces oversampling to be at least 2x.
BP BP Phone High order elliptical filter to bandpass a specific frequency region. Cutoff regulates the level of non-linearity. Resonance regulates the downsampling. Note that this filter only works properly for no oversampling and x2 oversampling.
     
Notch Linear SVF Zero delay feedback filter based on Andy Simper’s (Cytomic) SVF filter algorithms. Good for transparent filtering.
Peak Linear SVF Zero delay feedback filter based on Andy Simper’s (Cytomic) SVF filter algorithms. Good for transparent filtering.
Notch Linear RBJ Cookbook Notch filter.
Noise Muck Very subtle effect which only adds a tiny bit of multiplicative noise. Only audible on pure tones such as sine waves or triangles.
     
Wah Crybaby Emulation of a wah-wah filter based on a paper by M. Holters, this one took quite some doing to get to work. It’s heavy on the CPU, but sounds pretty authentic.
Wah Crybaby high Emulation of a wah-wah filter based on a paper by M. Holters, this one took quite some doing to get to work. It’s heavy on the CPU, but sounds pretty authentic. This one deliberately uses an incorrect sampling rate to obtain a higher pitched sound.
Wah Crybaby low Emulation of a wah-wah filter based on a paper by M. Holters, this one took quite some doing to get to work. It’s heavy on the CPU, but sounds pretty authentic. This one deliberately uses an incorrect sampling rate to obtain a lower pitched sound.
Wah Weeping Demon This is a model of the weeping demon wah pedal, originally modelled by Chet Gnegy and used with permission. Cutoff controls the wah level. Cutoff controls the pre-highpass.
Wah Weeping Demon II This is a model of the weeping demon wah pedal, originally modelled by Chet Gnegy and used with permission. Cutoff controls the wah level. Cutoff controls the pre-highpass. This one is much more bassy and prone to high resonance peaks.
Vowel Vowel SVF This filter uses 3 band pass filters whose cutoff and resonance are chosen to imitate different vowel sounds.
Vowel Vowel RBJ This filter uses 3 band pass filters whose cutoff and resonance are chosen to imitate different vowel sounds.
     
Fb Phaser (OTA) 4 pass phaser based on a series allpass filters with an additional feedback. Note that this one frequently has problem with spline voltage curves.
Fb Phaser (FET) 4 pass phaser based on a series allpass filters with an additional feedback.
Fb Delay Feedbok Non-linear phaser like filter with relatively long delays and distortion of difference signal.
Fb Phase Mangler Experimental
Exp Experimental This one is an extremely dangerous experimental thingamabob. It contains an allpass phaser, a saturating lowpass, some distortion gibberish and some feedback. Be careful with this thing as it is highly unstable, especially when you’re combining it with a waveshaper.
Fb Comb filter Basic comb filter. Set resonance one to have alternating notches between left and right (wide) or zero for mono phasing. Waveshaper is applied before the comb.
     
Mod Modulon Modulon works by modulating the signal with a set frequency and filtering the result. Note that this version has been superseded by the Tuned modulon which can actually be tuned properly.
Mod Metallic Odd combination of frequency and ring modulation. Highly recommend running this thing over pure tones only (sines, tris and such).
Mod Frazzle Odd combination of frequency and ring modulation.
Mod Tuned modulon Modulon works by modulating the signal with a set frequency and filtering the result. Considering that this filter is based on ring modulation, tuning is important. It is also highly recommended to use this filter in combination with keytracking.
Mod Tuned modulatrix Modulatrix works by modulating the signal with a set frequency and filtering the result. Considering that this filter is based on ring modulation, tuning is important. It is also recommended to use this filter in combination with keytracking.
Mod Modulator Passes a lowpassed version of the signal and multiplies it with the signal itself. This filter is meant for sounds with limited high frequency content as it will sound awful with rich sounds.
     
Dyn Athena Exciter A subtle exciter. Cutoff dials in the effect, resonance manipulates the dynamics. Athena compresses the signal, and then multiplies the compressed signal with a half-wave rectified copy of its middle band to add extra harmonics to the attack of the signal. While subtle, this can liven up dull muffled synths and drums.
     
Dist Broken Connection While it is a messy filter, it is still one of my favourites. Be careful with this one. It was actually sort of an accident, but it seems pretty stable and pretty unique. It is not invariant under oversampling particularly in the low frequency regions where it likes to lead a life of its own. It’s based on the kr0g filter, but including a voltage inversion step in the feedback path. Here low voltage is converted to high voltage and vice versa (not to be confused with a polarity switch!). One problematic aspect of this filter however is that it tends to produce output even when there is no input.
Dist Monstro A distortion with a vowel filter in the loop.
Dist Crunch Lowpasses the signal to isolate fundamentals. Distorts lowpassed signal, then highpasses this distorted signal and runs the right channel through a very short delay (widening). The result is fed back into the HP side to get a comb effect over the distortion. Cutoff controls frequency of the HP signal, while resonance controls the gain (more crunch).
Dist PWM Potatoes LP Emulation of PWM modulation. Can be used to make scrunchy sounds. Cutoff controls cutoff of the post-PWM filter, resonance controls the oversampling of the pulse generator.
Dist PWM Potatoes BP Emulation of PWM modulation. Can be used to make scrunchy sounds. Cutoff controls cutoff of the post-PWM filter, resonance controls the oversampling of the pulse generator.
Dist Bit reduction Bitdepth reduction. Cutoff slider reduces the bitdepth. A filter is run before the bitcrusher which splits off the bass, to add it back later after the bitcrusher. Setting the resonance to zero disables this filter. Note: This thing sounds nice paired with some tanh distortion.
Dist Sine Take the sine of the signal. Cutoff controls frequency, resonance controls mix. Simple, but surprisingly satisfying. Use on basses, not high frequency content.
Dist King of Tone Modelled after the King of Tone pedal. Warning: This one doesn’t respond nicely to live updating the resonance parameter without interia or very sharp gain transitions. It can produce clicks in such scenarios.
Dist Wavefolder Lockhart wavefolder based on a model by Esqueda et al (2017). Cutoff controls strength, resonance controls bias. Note that these are very sensitive to input gain.
Dist Multi-Wavefolder A stack of lockhart wavefolders based on a model by Esqueda et al (2017). Cutoff controls strength, resonance controls bias. Note that these are very sensitive to input gain.
Dist Serge Wavefolder A stack of lockhart wavefolders based on a model by Esqueda et al (2017). Cutoff controls strength, resonance controls bias. Note that these are very sensitive to input gain.
     
Pitch Octaver (Down) This chunky monkey can be used to add deep bass. Recommended for monophonic sounds. Octaver adds bass one and two octaves down. Cutoff transitions between dry and wet. Resonance switches between using octave 1 and 2. Note: This effect is best applied only on the mid channel (left and right can easily go out of phase resulting in cluttered stereo image).
Pitch Octaver (Up) This filter can be used to add some higher harmonics. Recommended for monophonic sounds only. Cutoff transitions between dry and wet, while resonance switches between using octave 1 and octave 2.
Pitch Vibrato Simple vibrato effect.
Pitch Spin Emulation of a spinning sound source.
     
Verb Metallic diffuser Allpass-based reverb. Resonance around 0.5 is typically reverb level. Higher resonances lead to stranger soundscapes, with a sudden behavior shift around 0.9. Cutoff increases internal delays. Low cutoffs lead to metallic sounds. High cutoffs to more natural delay-type sounds.
Verb Sproing Basic allpass reverb which simulates a small room with little damping.
Verb Worp Allpass-based reverb. Similar to the structure used in the older reverbs often used on ambient tracks. Tip: For a lot of drama, add a *tiny* bit of LFO modulation to the cutoff (size) parameter of this one.

Additional notes