mvclpf1 — Moog voltage-controlled lowpass filter emulation.
Mvclpf1 is an digital implementation of the 4th-order (24 dB/oct) Moog ladder filter originally written by Fons Andriaensen. According to the author, mvclpf1 "is a fairly simple design, and it does not even pretend to come close the 'real thing'. It uses a very crude approximation of the non-linear resistor in the first filter section only. [...] [I]t's [a] cheap (in terms of CPU usage) general purpose 24 dB/oct lowpass filter that could be useful".
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.
ain -- input signal.
xcf -- filter cutoff frequency. The useful range is around six octaves below and above middle C (pch 8.00).
xres -- resonance, limited to the interval [0,1].
Here is an example of the mvclpf1 opcode. It uses the file mvclpf1.csd.
Example 555. Example of the mvclpf1 opcode.
See the sections Real-time Audio and Command Line Flags for more information on using command line flags.
<CsoundSynthesizer> <CsOptions> -odac </CsOptions> <CsInstruments> 0dbfs = 1 instr 1 kenv linen p4,0.1,p3,0.1 ain rand kenv kfr expon 220, p3, 1760 asig mvclpf1 ain,kfr,0.9 out asig endin </CsInstruments> <CsScore> i1 0 5 0.9 </CsScore> </CsoundSynthesizer>