HOORAY! Was: [sdiy] Rene's ms20 filter clone

[Karl Ekdahl]

It's working!

Thank you, all of you are too kind as usual. Now i'm
probably not going to be the one too kind to my
neighbours for a while...


Karl

--- harrybissell <harrybissell at prodigy.net> skrev:

> The MS-20 filter is a Sallen-Key design... it should
> be screaming at you
> 
> and trying to tear your face off at most settings. 
> If it seems "subtle"
> 
> to you, its not working right yet...
> 
> H^) harry
> 
> Karl Ekdahl wrote:
> 
> > The problem is that there isn't really a point
> where
> > thing start/stop happening, it's just decaying
> > linearly in volume & *i think* cutoff. I can hear
> and,
> > very much, see (I have a soundcard-scope) the
> > resonance though so that is working now.  and it
> seems
> > to me that there are no sub-frequencies laying
> > around..
> >
> > thanks!
> >
> > Karl
> >
> > --- jays at aracnet.com skrev:
> >
> > > Karl,
> > >
> > > That might be the way it works.
> > >
> > > There is not a lot in the expo circuit to
> control
> > > the scaling and base freq. So it could drive the
> > > frequency down to very low (sub-audio) and you
> > > wouldn't hear anything or it could even cut the
> > > signal off completely.
> > >
> > > Here's an experiment. Put a very low freq signal
> > > (20-30Hz) into the filter, turn the freq pot to
> > > where you see a difference in the signal on a
> scope
> > > or hear a difference in the sound. Do the same
> with
> > > a high freq (12 kHz or more). Measure the
> voltage at
> > > the pot wipper in each case. Ok if you know the
> > > frequency and the voltage you can figure out
> where
> > > the minimum and maximum usable voltage is and
> figure
> > > out what the scale is (whether its really
> 1V/oct).
> > >
> > > If you don't have a scope or frequency counter
> but
> > > do have a computer with audio software you might
> be
> > > able to figure the frequencies you're using.
> > >
> > > Jay S.
> > >
> > > Karl Ekdahl wrote:
> > >
> > > > After looking at the schematic i can't
> possibly
> > > > understand how it would *not* work as a vca?
> Where
> > > is
> > > > the signal supposed to go when the cutoff is
> > > turned to
> > > > -15v? I found a shorted-out cap and a 470 ohm
> > > resistor
> > > > instead of 470k at the base of the
> expo-converter,
> > > so
> > > > now i can hear suttle resonance and frequency
> > > changes
> > > > while turning the pots. But still the volume
> goes
> > > to
> > > > zero while turning the CV pot all the way
> down?
> > > Where
> > > > am i supposed to find the signal when it's
> turned
> > > > down??
> > > >
> > > > Karl
> > > >
> > >
> > >
> 
>