Moogvcf must process signals normalised in [-1,1] otherwise you must preescale the
signal prior entering the filter or with the new preescaling parameter in moogvcf. This
was necessary to allow softclipping of the feedback inside the filter (the "resonance")
at a given input level.
Hope this helps!

Josep  M Comajuncosas

Jean-Michel DARRÉMONT wrote:

> Hi,
>
> I've been trying  opcode with the following .orc&.sco(Hans Mikelson
> vco exemple):
>
> sr = 44100
> kr = 4410
> ksmps = 10
> nchnls = 2
>
> instr 10
> idur = p3 ; Duration
> iamp = p4 ; Amplitude
> ifqc = cpspch(p5) ; Frequency
> iwave = p6 ; Selected wave form 1=Saw, 2=Square/PWM, 3=Tri/Saw-Ramp-Mod
> isine = 1
> imaxd = 1/ifqc*2 ; Allows pitch bend down of two octaves
> kpw1 oscil .25, ifqc/200, 1
> kpw = kpw1 + .5
> asig vco iamp, ifqc, iwave, kpw, 1, imaxd
> ayn moogvcf asig, 1000, .5
> outs ayn, ayn ; Ouput and amplification
> endin
>
> ;SCORE:
> f1 0 65536 10 1
> ; Sta Dur Amp Pitch Wave
> i10 0 2 20000 5.00 1
> i10 +  .  .          .       2
> i10 . . . . 3
> i10 . 2 20000 7.00 1
> i10 . . . . 2
> i10 . . . . 3
> i10 . 2 20000 9.00 1
> i10 . . . . 2
> i10 . . . . 3
> i10 . 2 20000 11.00 1
> i10 . . . . 2
> i10 . . . . 3
> e
>
> but I only get a silent sound file with this error message:
>
> MIT Csound: 3.51 (Jan 26 1999)
> (Mills/PPC: 3.5.1)
> orch now loaded
> audio buffered in 8192 sample-frame blocks
> writing 65536-byte blks of floats to Bardamu:Csound outputs:vco.aif (AIFF)
> SECTION 1:
> ftable 1:
> new alloc for instr 10:
> B  0.000 ..  2.000 T  2.000 TT  2.000 M:      Inf      Inf
> B  2.000 ..  4.000 T  4.000 TT  4.000 M:      Inf      Inf
> B  4.000 ..  6.000 T  6.000 TT  6.000 M:      Inf      Inf
> B  6.000 ..  8.000 T  8.000 TT  8.000 M:      Inf      Inf
> B  8.000 .. 10.000 T 10.000 TT 10.000 M:      Inf      Inf
> B 10.000 .. 12.000 T 12.000 TT 12.000 M:      Inf      Inf
> B 12.000 .. 14.000 T 14.000 TT 14.000 M:      Inf      Inf
> B 14.000 .. 16.000 T 16.000 TT 16.000 M:      Inf      Inf
> B 16.000 .. 18.000 T 18.000 TT 18.000 M:      Inf      Inf
> B 18.000 .. 20.000 T 20.000 TT 20.000 M:      Inf      Inf
> B 20.000 .. 22.000 T 22.000 TT 22.000 M:      Inf      Inf
> B 22.000 .. 24.000 T 24.000 TT 24.000 M:      Inf      Inf
> end of score.          overall amps:      Inf      Inf
> 0 errors in performance
> 130 65536-byte soundblks of floats written to Bardamu:Csound outputs:vco.aif (AIFF)
>
> The  opcode works fine.
> Do I forget something or is there a bug in .
>
> Thanks for any help.
>
> --
> Jean-Michel DARREMONT