mvclpf2 — Moog voltage-controlled lowpass filter emulation.
Mvclpf2 is an digital implementation of the 4th-order (24 dB/oct) Moog ladder filter originally written by Fons Andriaensen. According to the author, mvclpf2 "uses five non-linear elements, in the input and in all four filter sections. It works by using the derivative of the nonlinearity (for which 1 / (1 + x * x) is reasonable approximation). The main advantage of this is that only one evaluation of the non-linear function is required for each section".
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 mvclpf2 opcode. Play mvclpf2.csd
Example 646. Example of the mvclpf2 opcode.
See the sections Real-time Audio and Command Line Flags for more information on using command line flags.