butter and pole locations

[Haible_Juergen#Tel2743]

> Maybe that's true because a Sawtooth always sounds like a sawtooth, a > 
square
> sounds like a square, a triangle sounds like a triangle...

True in theory for ideal waves, not at all true in real VCOs !

>  it is not a Butterworth "optimal" filter... but it

The butterworth stuff is interesting. But as far as I know,
there wasn't any commercial synth with butterworth 4pole
filter. Most 4pole filters start from real, negative poles (without
resonance; with feedback applied they wander apart in an "X"-
shape.) In case of the Moog, Oberheim 4p, various ARP
4p, Prophet 4p (both old and new), and many others, you start with
4 identical pole locations. The VCS3 and TB303 have different
start values for their pole locations (but still all of them are real
and negative, without feedback applied).
(BTW, has anybody yet calculated the exact locations / pole spread
for the diode ladders?)
The Roland cascaded SV 4p-filters might be different ... anybody
knows if *they* start on an arc (as in a butterworth)?

JH.