moogladder
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## moogladder

moogladder — Moog ladder lowpass filter.

## Description

Moogladder is an new digital implementation of the Moog ladder filter based on the work of Antti Huovilainen, described in the paper "Non-Linear Digital Implementation of the Moog Ladder Filter" (Proceedings of DaFX04, Univ of Napoli). This implementation is probably a more accurate digital representation of the original analogue filter.

## Syntax

    asig moogladder ain, kcf, kres[, istor]

    asig moogladder ain, acf, kres[, istor]

    asig moogladder ain, kcf, ares[, istor]

    asig moogladder ain, acf, ares[, istor]

## Initialization

istor --initial disposition of internal data space. Since filtering incorporates a feedback loop of previous output, the initial status of the storage space used is significant. A zero value will clear the space; a non-zero value will allow previous information to remain. The default value is 0.

## Performance

asig -- input signal.

kcf/acf -- filter cutoff frequency

kres/ares -- resonance, generally < 1, but not limited to it. Higher than 1 resonance values might cause aliasing, analogue synths generally allow resonances to be above 1.

## Examples

Here is an example of the moogladder opcode. It uses the file moogladder.csd.

Example 587. Example of the moogladder opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    -odac   ;;;realtime audio out
    ;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
    ; For Non-realtime ouput leave only the line below:
    ; -o moogladder.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

    sr = 44100
    ksmps = 32
    nchnls = 2
    0dbfs  = 1

    instr 1

    kfe  expseg 500, p3*0.9, 1800, p3*0.1, 3000
    asig buzz  1, 100, 20, 1
    kres line .1, p3, .99	;increase resonance
    afil moogladder asig, kfe, kres
         outs afil, afil

    endin
    </CsInstruments>
    <CsScore>
    f 1 0 4096 10 1

    i 1 0 10
    e
    </CsScore>
    </CsoundSynthesizer>

## Credits

Author: Victor Lazzarini
January 2005

New plugin in version 5

January 2005.

Audio rate parameters introduced in version 6.02

October 2013.

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