Filters

Filter

A multi-mode filter with low-pass, high-pass, band-pass and band-stop (notch) responses from 12 to 48 dB/octave.

_images/FreeEffects_Filter.png

The following controls are provided:

Cut - set the cutoff frequency from 10 Hz to 20 kHz.

Filter Selector - set the filter type to lowpass, highpass, bandpass or notch.

Slope Selector - set the steepness of the frequency response to 12, 24, 36 or 48 dB/octave.

The lowpass filter shows the following frequency responses at 1 kHz:

_images/FreeEffects_FilterLP.png

The highpass filter shows the following frequency responses at 1 kHz:

_images/FreeEffects_FilterHP.png

The bandpass filter shows the following frequency responses at 1 kHz:

_images/FreeEffects_FilterBP.png

The notch filter shows the following frequency responses at 1 kHz:

_images/FreeEffects_FilterBS.png

In each case the darker line represents 12 dB/octave and the remaining lines 24, 36 and 48 dB/octave respectively.

AutoFilter

A resonant multi-mode filter with a built-in LFO modulator.

_images/FreeEffects_AutoFilter.png

The AutoFilter is divided into two sections: a filter and a modulator.

The filter section provides the following controls:

Filter Selector - set the type of the filter to LP24, LP12, HP, BP or BS.

Cut - set the cutoff frequency from 20 Hz to 20 kHz.

Res - set the resonance level from 0 to 100%.

The filter types available are:

LP24 - lowpass (24 dB/octave)

LP12 - lowpass (12 dB/octave)

HP - highpass (12 dB/octave)

BP - bandpass (12 dB/octave)

Notch - bandstop (12 dB/octave)

The modulation section provides the following controls:

Modulation Selector - set the modulation type to sine, sawtooth or square waveforms.

Sync - switch between frequency and tempo-based timing.

Rate - set the modulation rate from 0.01 Hz to 20 Hz or 8/1 to 1/32T according to the sync setting.

Depth - set the amount of modulation applied from -100% to +100%. Negative amounts use an inverted waveform affecting the phase and, for the sawtooth wave, the shape of the modulation applied.

DualFilter

A highpass and lowpass filter combination with full-range cutoff frequencies and resonance.

_images/FreeEffects_DualFilter.png

Both the filters provide the same controls:

Cut - set the cutoff frequency from 10 Hz to 20 kHz.

Res - set the resonance level from 0 to 100%.

With the highpass filter cut at 100 Hz and the lowpass filter at 2 kHz, the following response curves are presented for various resonance settings:

_images/FreeEffects_DualFilterQ.png

The darker line represents 0% with subsequent lines showing increments of 20% up to the maximum of 100%.