rezzy — A resonant low-pass filter.


A resonant low-pass filter.


ares rezzy asig, xfco, xres [, imode, iskip]


imode (optional, default=0) -- high-pass or low-pass mode. If zero, rezzy is low-pass. If not zero, rezzy is high-pass. Default value is 0. (New in Csound version 3.50) iskip (optional, default=0) -- if non zero skip the initialisation of the filter. (New in Csound version 4.23f13 and 5.0)


asig -- input signal

xfco -- filter cut-off frequency in Hz. As of version 3.50, may i-,k-, or a-rate.

xres -- amount of resonance. Values of 1 to 100 are typical. Resonance should be one or greater. As of version 3.50, may a-rate, i-rate, or k-rate.

rezzy is a resonant low-pass filter created empirically by Hans Mikelson.


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

Example 400. Example of the rezzy opcode.

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

; Select audio/midi flags here according to platform
; Audio out   Audio in    No messages
-odac           -iadc     -d     ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
; -o rezzy.wav -W ;;; for file output any platform

; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1

; Instrument #1.
instr 1
  ; Use a nice sawtooth waveform.
  asig vco 32000, 220, 1

  ; Vary the filter-cutoff frequency from .2 to 2 KHz.
  kfco line 200, p3, 2000

  ; Set the resonance amount.
  kres init 25

  a1 rezzy asig, kfco, kres

  out a1


; Table #1, a sine wave for the vco opcode.
f 1 0 16384 10 1

; Play Instrument #1 for three seconds.
i 1 0 3


See Also

biquad, moogvcf


Author: Hans Mikelson
October 1998

Example written by Kevin Conder.

New in Csound version 3.49