SV: Re: [sdiy] Nonlinearities in IR3109 filters

[Sean Costello]

In the Oberheim SEM filter, it seems like the diodes in the feedback path
would INCREASE the perceived Q for low settings of Q and high input
amplitudes. This is the opposite behavior from the Moog ladder, where
overdriving the filter input reduces the perceived Q.

Sean Costello

----- Original Message ----- 
From: "karl dalen" <dalenkarl at yahoo.se>
To: "Magnus Danielson" <cfmd at bredband.net>
Cc: <seancostello2003 at comcast.net>; <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, August 02, 2006 4:20 PM
Subject: SV: Re: SV: Re: [sdiy] Nonlinearities in IR3109 filters


>
> --- Magnus Danielson <cfmd at bredband.net> skrev:
>
>
> > > For instance many folks says (2pole SVF type ) SEM filter cant
resonate
> > > in sinus, ofcourse it can.
> >
> > I agree. It is designed not to normally, with intention. Just look at a
> > normal  cos/sin oscillator core, it is nothing but a normal
state-variable
> >filter in  a  particular setup.
>
> Exactly, and what do we have there in the feedback path, diodes!
>
> Wich reminds us/me that a VCO is a filter and a filter is a VCO,
> wich got me reminding, why is'nt anyone using a ADSR as VCO?
>
> Current/voltage controlled ADSR parameters to the clocked freq gives a
> VCO with very easy controll of seamless fading from any start shape
> to any end shape oif the shapes given by the ADSR function.
>
> KD