from rebirth manual:
Introduction
The PCF is an extremely versatile synth effect. It allows you to change the sound,
from any of the sections in ReBirth RB-338, in a number of ways.
The PCF is an insert effect that can be applied on the output of one of the sections.
There is only one PCF. This means that only one section at a time can use it.
Basically, the PCF is a filter with an envelope, just like there are filters with envelopes
in the synth sections. You route the output of one of the sections through the
PCF and thereby shape the tonal character of the sound.
The main difference between the PCF and the synth filters is that this filter is “pattern
controlled”. There are a large number of preset patterns that allow the filter to
“superimpose” pumping effects, slow sweeps and rhythmic phrasing onto the
sound. But before we go into the technical details, let us give you an example of
how the PCF can be used.
How the PCF Works - Background Information
The PCF is built from two major components:
1. The Filter
This is a 12dB/octave (2-pole) design that can be switched between lowpass and
bandpass operation and has cutoff and resonance controls.
2. An Envelope with Patterns
This is a simple Attack/Decay envelope. The Decay time can be set on the PCF
panel. The Attack is controlled via the Patterns, as described below. By using the
AMT (Amount) control on the PCF panel, you can set to what extent the envelope
affects the filter.
About the Patterns
There are a large number of preset patterns that provide various rhythmic effects.
They do this by controlling the following envelope parameters:
• Retriggering
This is the most basic type of control. In Pattern 0 for example the envelope is
retriggered (restarted) at each whole note, in pattern 1 on each half note etc.
• Dynamic and Attack control.
In many of the Patterns, the envelope is triggered with different dynamics on
different “beats”. Some “beats” also have a different attack.
The Patterns are preset, they can not be changed. Their length vary, most are one or
two bars, but some have been created in odd time signatures (a full list can be found
on page 205 and onwards).
http://www.zikinf.com/articles/mao/gfx/rbpcf.jpg
http://www.harmony-central.com/Features ... ebirth.jpg
<font size=-1>[ This Message was edited by: bronYaur on 2006-01-08 05:20 ]</font>
But really it's nothing more than a LP/BP filter with an envelope that uses preset patterns to modulate some of the parameters. It shouldn't be too hard to build something like this in modular i think, using a stepsequencer module to modulate the filter. I don't really know modular myself though so maybe an expert could shed more light on it.
