Doepfer A-123 24dB High Pass (no longer available) - 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