Screaming Ladder Filter
Multimode ladder filter with a blast!
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Screaming Ladder Filter
INPUT for audio signal.
PITCH for pich tracking, controlled by knobs K-TRK (keyboard tracking) for filter (black) and feedback delay (yelow).
ENV for envelope generator, knob ENV controlls envelope amount passed to cutoff frequency controll.
FM input for audio frequency moduladion, knob FM controlls modulation amount .
Standard A and B modulation inputs.
OUPUTS: just one audio output for filtered signal.
a) Black: filter controlls
CUTOFF is frequency from range 5Hz-20kHz where signal is going to be filtered, based on the filer mode.
MODEs to choose from: LP (low-pass) BP (band-pass) HP (high pass) NO (notch) and LP again, to make it possible to blend it with neighbouring notch. There are breakpoints for each mode and each two combined. MORPH button allowing you to smoothly blend between modes.
SLOPE is setting for filter curve tilt, ranging from 0dB/oct (0 poles) to 24dB/oct (4 poles)
in 3dB stepes or smoothly with MORPH engaged.
K TRK (black) contolling cutoff frequency modulation from pitch input. Middle C (note 60) is neutral point where this knob doesnt do anything. It can be positive (higher cutoff for higher notes) or negative (lowe cutoff for higher notes).
ENV controlls envelope generator ammount, connected to ENV input. Can be positive or negative (inverted envelope).
FM controlling frequency modulation ammount of modulator connected to FM input.
SPACE knob is for band-pass and Notch mode filtering width. Higher the setting, weider the filtering. Note, that those modes are created from two separate LP and HP filters, so with higher resonanse you can create formant effects while adjusting SPACE parameter. It has no effect for LP and HP modes.
b) Orange: resonanse controlls
RES is the ammount of empahis at the cutoff point. At values >0.5 green diode lights up, indicating self oscillation mode, up to extreme amounts at maximum value.
COMP controlls gain loss compensation when increasing resonanse, from no compensation at value 0 to maximum compensation, equals no gain loss at maximum value. Note, that in various settings resonance compasation might leads to extreme distortion at post filter stage (which is fine ofcourse!).
c) Red: distortion
PRE is amount of additional gain added before filter itself, which leads to gentle distortion while filtering. This is not hard-clipped pre filter distortion, so at extreme settings (for example fully opened filter with a lot of PRE gain) might leads to POST distortion aswell. In other words, this distortion stage is heavly dependent on filter settings (cutoff, mode, slope, resonanse etc). Red squared lights indicates how much distortion is affecting actual signal.
POST is amount of additional gain added after filter and before hard-clipping distortion stage at the filter output. Its more agressive and wont let you blow your PA during extreme filtering. It also has 3 lights indicating distortion amount.
d) Yellow: feedback
FB SRC is feedback source selector, from 100:0 (100% pre post distortion) to 0:100 (100% post distortion). It has huge impact of how feedback will work and sound.
FBACK controlls feedback amount.
DELAY controlls delay time of feedback signal patch. At minimum setting delay is near 0, like in typical filter feedback, but as you increase delay time, it starting to "kind of" self oscillate. Also, delay time is tuned to pich, controlled by K TRK knob.
K TRK (yellow) controlls pich modulation of tuned delay time. At maximum setting, you'll have consistent modulation regardles of note played or in some settings, allows you to play melodies with delayed feedback effect. It can go from negative to positive values, just like K TRK for filter itself.
GENGERAL NOTES: this filter allow some extreme settings, on purpose. This way, you can create unpredictable sounds, but it might be tricky at first. As you go more into extremes, settings might getting more and more depending from each other, especially feedback and pre/post distortion in relation to FB SRC and feedback DELAY. Same with extreme resonance with high resonance compensation, high SPACE bandpass/notch self oscillation, low dB/oct slope settings etc.
There are many combinations, that might leads to no sound at all (similar to hardware filters with feedback) which is nice sweet spot to find interesting breakpoint and tweak other parameters. Also, it is possible to "blow up" filter completly at some ultimate extremes, if filter wont sound anymore, just turn off/on reaktor engine in the upper right corner. I could recude some ranges to avoid that, but i probably wont, as in 99% settings it might led to interesting filter chokes, and if you are not going to test how far you can go with usless sound, it wont happen (and if it will happen, its safe for your PA as filter have hard-clipping distortion at the output).