Description

A bank of filters in which the cutoff frequency can be separated under user control

Syntax

ares vlowres asig, kfco, kres, iord, ksep

Initialization

iord -- total number of filters (1 to 10)

Performance

asig -- input signal

kfco -- frequency cutoff (not in Hz)

kres -- resonance amount

ksep -- frequency cutoff separation for each filter: the first filter has a kfreq cutoff, the second has a kfreq + ksep and the third kfreq + 2*ksep and so on, depending on the number of filters.

vlowres (variable resonant lowpass filter) allows a variable response curve in resonant filters. It can be thought of as a bank of lowpass resonant filters, each with the same resonance, serially connected. The frequency cutoff of each filter can vary with the kcfo and ksep parameters.

Examples

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

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

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


instr 1

kamp init p4
asig vco2  kamp, 110			;saw wave
kfco line 30, p3, 300			;vary the cutoff frequency from 30 to 300 Hz.
kres = 20	
ksep = p5				;different resonance values
iord = p6				;and different number of filters
aout vlowres asig, kfco, kres, iord, ksep
aclp clip aout, 1, 1			;avoid distortion
     outs aclp, aclp
     
endin
</CsInstruments>
<CsScore>
f 1 0 16384 10 1	;sine

s
i 1 0 10 .1 5  2	;compensate volume and 
i 1 + 10 .1 25 2	;number of filters = 2
s
i 1 0 10 .01 5  6	;compensate volume and 
i 1 + 10 .04 15 6	;number of filters = 6

e
</CsScore>
</CsoundSynthesizer>

Credits

New in Csound version 3.49