Wiardgroup

hi jr,

basically, you feed an audio signal into the filter audio input and 
you patch the filter output to an amp for monitoring. with the 
frequency control knob fully open and no resonance added, you hear 
the waveform or audio without any coloration or filtering.

you then turn the frequency knob counter clockwise to eliminate all 
the audio. once you don't hear any audio at all, the filter is closed.
if you turn the knob from zero to max , you are controlling the 
filter much the same way a VCA behaves. 

now most filters have 1 input without an attenuator and 1 or 2 inputs 
with attenuators to voltage control the amount for the frequency 
range. to use the filter as a VCA, you send a control voltage to the 
frequency input on the filter. you can use an EG, an LFO , etc. to 
open and close the filter. 

to avoid hearing any filtering or coloration of the audio, it is best 
to avoid slow attack times, you basically want zero attack, zero 
decay, full level sustain or duration to open the filter quickly and 
whatever release level you want to close the filter accordingly (zero 
release, the filter snaps shut immediately, whatever release setting 
you chose and the filter closes accordingly).

using a filter as a vca is a good tool when you have run out vca's.

the best way to learn more about modular synthesis and its techniques 
is to recreate patches from owners manuals, academic books and 
suscribing to synth newsgroups. here are a couple of urls to point 
you in the right direction. good luck.

http://www.angelfire.com/music2/theanalogcottage/

http://theworld.com/%7Ejamzen/theBachWorks/arpman.html

http://home.t-online.de/home/BriJo.Mueller/basisxyz.html

http://www.cim.mcgill.ca/~clark/nordmodularbook/nm_book_toc.html

http://ds.kobedenshi.ac.jp/doepfer/

http://www.creativesynth.com/

http://www.modularsynth.com/

http://hem.passagen.se/tkolb/art/synth/intro_e.htm

http://www.musicsynthesizer.com/

i can't list every url i have, but this should get you started. 
always follow the links at each site you visit to find out more 
sources out there. the last link is a great portal to the synth DIY 
world out there, it will inform you of the concepts and theories 
behind the front panels of the modules.

happy surfing and discovering,
RM


--- In wiardgroup@yahoogroups.com, "jrbulldogge <jrbulldogge@y...>" 
<jrbulldogge@y...> wrote:
> Well, I'm not exactly a newbie to synthesis, but am just begining 
my 
> venture into the world of analog modulares, and I had a question 
> that is probably totally basic, but here goes anyway.  Please feel 
> free to laugh, curse or otherwise direct insults my way for what is 
> probably very obvious:).
> 
> I noticed in the "Noise Ring" page that one of the mp3s had a NR 
and 
> a Borg Filter together.  One of the Borg was being used as a 
> standard filter, but the other was acting as a VCA.  Now, I've read 
> about filters being used as VCAs before, and it seems particularly 
> in conjunction with vactrol-based filters.  But, I'm not entirely 
> sure how this would work.  I assume that if you adjust the cut-off 
> in any way that it would be, well, filtering the sound.  So, then, 
> how do you get a filter to amplify the sound instead of filtering 
> it?  Perhaps with the resonance somehow?  
> 
> Again, sorry if this is painfully obvious, but I went to a football 
> game today so maybe my IQ has been lessened by association:).
> 
> J.R. "Bulldogge" Ross
> & Snuffy, too:)