SV: Re: SV: RE: Re: [sdiy] Rene's ms20 filter clone

[Karl Ekdahl]

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
> > 
> 
>