Doepfer A-124 Wasp Filter - Manual

doepfer System A - 100 Wasp Filter ( VCF 5) A-124
1
1. Introduction
Module A-124 (WASP FILTER) is a special voltage-
controlled multimode filter with a cut-off slope of
-12dB / octave.
The special feature of the A-124 is the peculiar
electronic circuitry of the Wasp synthesizer manufac-
tured at the end of the seventies by the UK company
EDP (Electronic Dream Plant). This synthesizer is well
known for its eye-catching black/yellow wasp design
and its distinctive filter. Its circuitry "abuses" digital
inverters as analog operational amplifiers leading to
distortions and other "dirty" effects that generate the
specific sound of this filter.
Our version is equipped with a band pass output and
a combined low/notch/high pass output. For this
latter output a control knob defines the relative
amounts of low and high pass signals. If both si-
gnals appear at the same level (i.e. middle position of
the Mix knob) one obtains a notch filter. Otherwise the
low or high pass signal predominates.
Resonance can be adjusted manually. The filter can't
go into self oscillation, in contrast to most of the other
VCFs in the A-100 system.
The cut-off frequency can be adjusted manually, or
by voltage control. Two CV inputs are available.
Audio
In
CV 2
CV 2
BP Out
LP/HP Out
Res.
CV 1
A-124
WASP FILTER
Frq.
Level
Mix