[sdiy] Multi Tapped ladders (was FatMan Hacking )

[Tony Allgood]

Hi all,

As already mentioned I have got the schematic for a multi-tapped ladder
filter. No great shakes really circuitry wise, but it does make a great
module for playing about with new responses. For me, I tend to take the
feedback path straight from the top rung of the ladder. The module was
designed to be normalised that way. The feedback point's input is
available as an input from the front panel, which in itself can be used
as an additional (inverting wrt to the ordinary input) audio input.
Taking the tap from other points down the ladder was less than
impressive.

However, it is a very good idea to add some sort of non linear element
in the feedback loop too. A full wave rectifier, for example, gives
startling results... there's a .wav file on the page to illustrate this.
Also additional filtering of the feedback path itself is a worthwhile
trick. Additional HP filtering can lead to huge bass sounds at high
resonance.

But the real benefit of any multitapped filter is the ability to
add/subtract the different outputs together to create 'new' responses.

Interestingly Doepfer now seems to be thinking about a 8 way tapped
ladder filter to replace the other one that caused a stir around here a
little while ago.

Regards,

Tony Allgood, Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.oakleysound.com/projects.htm
My music: www.mp3.com/taklamakan