[sdiy] TomG's 9v diode ladder VCF

[tomg@efm]

Ok the files are all fixed....enjoy
http://groups.yahoo.com/group/EFM_Synth/files/cookbook/vcf6se-sd.gif
http://groups.yahoo.com/group/EFM_Synth/files/cookbook/vcf6se-pc.gif
Tom




> oops....I just did a quick breadboard...too much res....change
> the feedback resistor on the res opamp from 47K to 2K2 or
> just remove the 10K resistor from the inverting input to gnd.
>
> Tom
>
>
>
> > Try this version....You could say I made it for Ben but everybody
> > should enjoy this one...it's dead simple!
> > http://groups.yahoo.com/group/EFM_Synth/files/cookbook/vcf6se-sd.gif
> >
> > Untested 2x2" DIY layout....but confidence is high! Somebody do it up
> > real quick so Ben will know it works.....
> > http://groups.yahoo.com/group/EFM_Synth/files/cookbook/vcf6se-pc.gif
> >
> > It's 2 ics 12 diodes and 1 dual-npn (or matched 3904s) 16 resistors
> > and 3 caps.....good luck..
> >
> > Tom
> >
> >
> >
> >
> > > OK I'll do the hacks!  I tested it with random selected
> > > 1N4148 diodes.
> > >
> > > I too prefer the Transistor Ladder... but the diode ladder is
> > > nice too. I've heard that the differences are mainly to be found
> > > in advanced mathematics that hurts my head...
> > >
> > > In simple terms (as I understand it...) The Transistor ladder
> > > sections are better separated... the diode sections load each other
> > > more due to the lack of gain in the diodes. So the 24db filter starts
to
> > > look more like 18db or so at some ladder currents.
> > >
> > > One place to get some matching is the capacitors... I'm using 2% in
> > > both filters.
> > >
> > > Anyone know about the difference between the original MiniMoog ladder
> > > (with the 150 ohm bias resistors) and the newer model (with the 1K
> > > bias resistors ???)
> > >
> > > H^) harry
> > >
> > >
> > > >From: DCMagnuson at aol.com
> > > >To: Plutonique9 at symbiocom.com, synth-diy at node12b53.a2000.nl
> > > >Subject: Re: [sdiy] TomG's 9v diode ladder VCF
> > > >Date: Thu, 12 Apr 2001 11:22:43 EDT
> > > >
> > > >In a message dated 4/12/01 10:51:00 AM Eastern Daylight Time,
> > > >paia2720 at hotmail.com writes:
> > > >
> > > > > You might want to consider a chip like the MAD1108 which has 8
> diodes
> > > > >  in it. Diode PAIRS need to be matched... not the diodes in one
> "leg"
> > > > >
> > > > >  TomG's pc board for the diode ladder filter is not layed out this
> > way.
> > > >I'm
> > > > >  gonna hack it to be "improved" one day... but it works OK without
> > > > >  any matching as well...
> > > >
> > > >I have one of Tom G's VCF-6's, and I used no diode matching at all (I
> > used
> > > >1N914's) .  The filter sounds good to my ears, but I don't have a
> matched
> > > >VCF
> > > >to compare it to.
> > > >
> > > >That said, I still prefer the sound of my 3046-based transistor
ladder
> > VCF.
> > > >Does anyone know if the lack of diode matching could be the reason?
> IE:
> > > >what
> > > >will the effects be because I did not match my diodes?
> > > >
> > > >Dave Magnuson
> > >
> > > _________________________________________________________________
> > > Get your FREE download of MSN Explorer at http://explorer.msn.com
> > >
> >
>