Doepfer

--- In Doepfer_a100@yahoogroups.com, "primatetom2003" 
<baltimorescience@h...> wrote:
> thank you those who replied re the greasy filter question.
> i read about the diode filter at the Doep website.  i'm unclear 
> about what effects diodes have on the sound and the q.
> 
> what does it sound like?  why is it not as easy to self resonate as 
> a different filter?
> ____________________________________t


it is not difficult to drive a diode filter into self oscillation.
when turning up the resonance on a a102, you will get that
self oscillation very early (around 9 o'clock position).
the problem is that the resonance changes, when you sweep the
cutoff frequency and vice versa. the two parameters are not 100%
independent. diode tolerances lead to some strange behaviour,
the resonance varies in loudness and maybe will disappear at some
point, when you change the cutoff frequency. this is a bit
different on each a102. thats why it is difficult to use a
self oscillating a102 as a sine oscillator. also the overall
loudness changes when you turn up the resonance, so you have to
re-adjust the input attenuator too. but besides this, the diode
filter sounds cool. i would describe it as a bit "untamed" :-)