tbvcf — Models some of the filter characteristics of a Roland TB303 voltage-controlled filter.
This opcode attempts to model some of the filter characteristics of a Roland TB303 voltage-controlled filter. Euler's method is used to approximate the system, rather than traditional filter methods. Cutoff frequency, Q, and distortion are all coupled. Empirical methods were used to try to unentwine, but frequency is only approximate as a result. Future fixes for some problems with this opcode may break existing orchestras relying on this version of tbvcf.
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. Should be normalized to ±1.
xfco -- filter cutoff frequency. Optimum range is 10,000 to 1500. Values below 1000 may cause problems.
xres -- resonance or Q. Typically in the range 0 to 2.
kdist -- amount of distortion. Typical value is 2. Changing kdist significantly from 2 may cause odd interaction with xfco and xres.
kasym -- asymmetry of resonance. Typically in the range 0 to 1.
Here is an example of the tbvcf opcode. It uses the file tbvcf.csd.
Example 455. Example of the tbvcf 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 ; Audio out Audio in No messages -odac -iadc -d ;;;RT audio I/O ; For Non-realtime ouput leave only the line below: ; -o tbvcf.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> ;--------------------------------------------------------- ; TBVCF Test ; Coded by Hans Mikelson December, 2000 ;--------------------------------------------------------- sr = 44100 ; Sample rate kr = 4410 ; Kontrol rate ksmps = 10 ; Samples/Kontrol period nchnls = 2 ; Normal stereo zakinit 50, 50 instr 10 idur = p3 ; Duration iamp = p4 ; Amplitude ifqc = cpspch(p5) ; Pitch to frequency ipanl = sqrt(p6) ; Pan left ipanr = sqrt(1-p6) ; Pan right iq = p7 idist = p8 iasym = p9 kdclck linseg 0, .002, 1, idur-.004, 1, .002, 0 ; Declick envelope kfco expseg 10000, idur, 1000 ; Frequency envelope ax vco 1, ifqc, 2, 1 ; Square wave ay tbvcf ax, kfco, iq, idist, iasym ; TB-VCF ay buthp ay/1, 100 ; Hi-pass outs ay*iamp*ipanl*kdclck, ay*iamp*ipanr*kdclck endin </CsInstruments> <CsScore> f1 0 65536 10 1 ; TeeBee Test ; Sta Dur Amp Pitch Pan Q Dist1 Asym i10 0 0.2 32767 7.00 .5 0.0 2.0 0.0 i10 0.3 0.2 32767 7.00 .5 0.8 2.0 0.0 i10 0.6 0.2 32767 7.00 .5 1.6 2.0 0.0 i10 0.9 0.2 32767 7.00 .5 2.4 2.0 0.0 i10 1.2 0.2 32767 7.00 .5 3.2 2.0 0.0 i10 1.5 0.2 32767 7.00 .5 4.0 2.0 0.0 i10 1.8 0.2 32767 7.00 .5 0.0 2.0 0.25 i10 2.1 0.2 32767 7.00 .5 0.8 2.0 0.25 i10 2.4 0.2 32767 7.00 .5 1.6 2.0 0.25 i10 2.7 0.2 32767 7.00 .5 2.4 2.0 0.25 i10 3.0 0.2 32767 7.00 .5 3.2 2.0 0.25 i10 3.3 0.2 32767 7.00 .5 4.0 2.0 0.25 i10 3.6 0.2 32767 7.00 .5 0.0 2.0 0.5 i10 3.9 0.2 32767 7.00 .5 0.8 2.0 0.5 i10 4.2 0.2 32767 7.00 .5 1.6 2.0 0.5 i10 4.5 0.2 32767 7.00 .5 2.4 2.0 0.5 i10 4.8 0.2 32767 7.00 .5 3.2 2.0 0.5 i10 5.1 0.2 32767 7.00 .5 4.0 2.0 0.5 i10 5.4 0.2 32767 7.00 .5 0.0 2.0 0.75 i10 5.7 0.2 32767 7.00 .5 0.8 2.0 0.75 i10 6.0 0.2 32767 7.00 .5 1.6 2.0 0.75 i10 6.3 0.2 32767 7.00 .5 2.4 2.0 0.75 i10 6.6 0.2 32767 7.00 .5 3.2 2.0 0.75 i10 6.9 0.2 32767 7.00 .5 4.0 2.0 0.75 i10 7.2 0.2 32767 7.00 .5 0.0 2.0 1.0 i10 7.5 0.2 32767 7.00 .5 0.8 2.0 1.0 i10 7.8 0.2 32767 7.00 .5 1.6 2.0 1.0 i10 8.1 0.2 32767 7.00 .5 2.4 2.0 1.0 i10 8.4 0.2 32767 7.00 .5 3.2 2.0 1.0 i10 8.7 0.2 32767 7.00 .5 4.0 2.0 1.0 e </CsScore> </CsoundSynthesizer>