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  • Filter reference

Filter reference

The Filter menus of Erosia offer a large selection of filters. These filters can be split into two groups:

  • The upper part of the Filter menus contains classic filters: Ladder LP1, Ladder LP2, Ladder LP4, SV LP2, SV LP4, Ladder HP1, Ladder HP2, Ladder HP4, SV HP2, SV HP4, Ladder BP2, Ladder BP4, SV BP2, SV BP4, Ladder Peak, and Par LP/HP filters. Refer to Classic filters.

  • The lower part of the Filter menus contains creative filters: Phaser, Vowel 1, Vowel 2, Formant 1, Formant 2, Spectral 1 to 5, and Spectral Frq Bst filters. Refer to Creative filters.

Note

The Filter menus are available in the Filter section of the Layers page and in the FX Bus section of the FX page.

Classic filters

The classic filters include the Ladder LP1, Ladder LP2, Ladder LP4, SV LP2, SV LP4, Ladder HP1, Ladder HP2, Ladder HP4, SV HP2, SV HP4, Ladder BP2, Ladder BP4, SV BP2, SV BP4, Ladder Peak, and Par LP/HP filters.

The name of each classic filter provides information about its characteristics:

  • Algorithm:

    • SV (State Variable) filters have a clean character.

    • Ladder filters are based on the classic ladder circuit used in early synthesizers.

  • Attenuated frequencies:

    • LP (lowpass) filters attenuate harmonics and signals above the cutoff frequency.

    • HP (highpass) filters attenuate signals below the cutoff frequency.

    • BP (bandpass) filters attenuate signals above and below the cutoff frequency.

    • Peak filters are bandpass filters with a very narrow band.

    • The Par LP/HP filter is the combination of a highpass filter and a lowpass filter routed in parallel (the signal is split and routed through each separately). As a result the filter removes a specific frequency band from the signal.

  • Steepness of the attenuation curve:

    • 1-pole and 2-pole filters (for example, LP1 or BP2) have a rather gentle slope that preserves more of the original sound.

    • 4-pole filters (for example, LP4 or BP4) affect the sound more frankly on their dedicated frequency range.

All the classic filters provide the following controls:

  • Cutoff: Adjusts the frequency below and/or above which signals will be attenuated.

  • Resonance: With values greater than 0, this control will boost a small frequency range around the cutoff frequency.

  • Key Tracking: Adjusts to which extent the Cutoff value follows the pitch of the played key.

Creative filters

The creative filters include the Phaser, Vowel 1 and Vowel 2, Formant 1 and Formant 2, Spectral 1 to 5, and Spectral Frq Bst filters.

Phaser

The Phaser filter creates a distinct comb filter effect by using an all-pass filter design that radically alters the phase relations in your signal. It provides the following controls:

  • Cutoff: Adjusts the center working frequency of the phaser’s comb filter effect. Changing this parameter will alter the tonality of your sound in a distinct and not always easily predictable way.

  • Resonance: Adjusts the depth and narrowness of the notches that the phaser imposes on the frequency spectrum, and thereby the intensity of the effect.

  • Key Tracking: Adjusts to which extent the Cutoff value is following the pitch of the played key.

Vowel 1 and Vowel 2

The Vowel 1 and Vowel 2 filters simulate the resonant frequencies of the human vocal tract in order to produce vowel-like sounds. They provide the following controls:

  • Cutoff: Adjusts the center frequency of the filter. Various distinct frequencies across the spectrum will produce different vowels.

  • Resonance: With values greater than 0, this control will emphasize the frequencies around the center frequency in order to create a sharper sound and enhance the effect.

  • Key Tracking: Adjusts to which extent the Cutoff value is following the pitch of the played key.

Formant 1 and Formant 2

The Formant 1 and Formant 2 filters are also designed to mimic the frequency response of the human vocal tract. These filters can be used to emulate the “talk box” effect. They provide the following controls:

  • Talk: Controls the shape of the frequency response. This control can be used to morph between vowel-sounds.

  • Size: Controls the center of the frequency response, analogous to the Cutoff control of the other filters.

  • Key Tracking: Adjusts to which extent the Size value is following the pitch of the played key.

Spectral 1–5 and Spectral Frq Bst

The Spectral 1–5 and Spectral Frq Bst (Frequency Boost) filters are based on a 3-band equalizer (EQ). They use movement of the EQ frequency and gain parameters to sweep across the spectrum, creating dynamic tonal shifts. They have different movement shapes and ranges, so that each one creates its own distinct sweeping pattern. The Spectral Frq Bst filter type uses only one band to boost or cut the specified frequency range. These filter types provide the following controls:

  • Freq: Sets the center frequency in the spectrum where the filter is focused.

  • Gain: Adjusts the emphasis or attenuation at the Freq value.

  • Key Tracking: Adjusts to which extent the Freq value is following the pitch of the played key.