AW: Re: Minimoog Filter Schematic Availa

[Magnus Danielson]

> 
> > BTW. Have more people than me noted that the ladder filter is really a cl=
> > ose
> > relative to a state-variable filter? If you hook in over another capacito=
> > r you
> > get diffrent filtering functions.
> >
> > Cheers,
> > Magnus
> 
> State variable ???
> State variables use integrator ( 1/s ) stages, while the Moog cascade uses
> RC-style stages ( 1/(1+s) ).
> Where is the link to state-variable ... adding another cap ?
> Please do tell !

Well, I can of course be totally of, but the cap is really the integrator here.
The transistors will also act as buffers in a way...

Recall that an integrator can be created with a capacitor with a op-amp acting
as the virtual ground circuit, this is how the typhical exponential RC 
behaiviour is removed. With a state-variable filter with CV control you 
replaces
the resistor with a transconductance....

As I said, I haven't figured it out fully... cause when I had I would know
exactly all the details, and have a boatload of mods :)

Maybe I should do a small spice simulation with pole-zero locations to see how
it works. Anyone got a library of real transistor models for me... I only have
the spice and what I could find on the web....

Cheers,
Magnus