DOEPFER A-100 Series - User Manual

doepfer
System A - 100
VCF 4 A-123
1
1. Introduction
Module A-123 (VCF 4) is a voltage-controlled high-
pass filter
, which filters out the lower parts of the
sound spectrum, and lets higher frequencies pass
through.
The
cut-off frequency
determines the point at which
filtering takes effect. You can control this manually, or
by voltage control (
filter modulation
, for instance by
an LFO). Two CV inputs are available.
The cut-off slope is -24 dB/octave. The circuitry uses
a Curtis CEM 3320 chip.
Voltage controlled resonance: on the VCF 4, reso-
nance can be controlled not just manually, but by
voltages as well, right up to self-oscillation. In this
case, the filter behaves like a sine wave oscillator.
FCV 1
Resonance
FCV 2
QCV
Audio
In
Level
Audio
Out
QCV
Frequency
A-123
VCF 4
FCV 2

Summary

1. Introduction to the A-123 VCF 4

2. VCF 4 Overview and Connections

VCF 4 Controls

Details the manual controls for the filter's level, frequency, FCV, QCV, and resonance parameters.

VCF 4 Inputs and Outputs

Lists and describes the module's connection points including audio and control voltage inputs/outputs.

3. Detailed Control Descriptions

Level (Lev.) Control

Attenuator for the audio signal entering the filter. Controls signal level.

Frequency (Freq.) Control

Adjusts the cut-off frequency (fc) below which frequencies are attenuated.

FCV (Frequency Control Voltage)

Input for voltage control of the cut-off frequency, enabling modulation.

QCV (Resonance CV Attenuator)

Attenuator for controlling the level of voltage applied to resonance.

Resonance (Res.) Control

Sets the filter's resonance or emphasis, affecting frequencies around cut-off.

4. Detailed In;Output Descriptions

Audio Input (Audio In)

Socket for patching audio sources into the filter for processing.

FCV 1 Input

Voltage input for controlling cut-off frequency, operates on 1V/octave rule.

FCV 2 Input

Voltage input for frequency control, level adjusted by attenuator.

QCV Input

Voltage control input for the filter's resonance parameter.

5. User Examples and Applications

6. Patch Sheet and Diagrams

DOEPFER A-100 Series Specifications