Doepfer A-108 6/12/24/48 Formant Filter - Manual

doepfer System A - 100 6/12/24/48 dB Low Pass A-108
1
1. Introduction
Module A-108 is a completely new, unique voltage-
controlled low pass/band pass filter based on the
well-known transistor ladder (Moog ladder).
The module has internally an 8 stage low pass filter
with different slopes available: 6, 12, 18, 24, 30, 36, 42
and 48 dB per octave. In the factory the outputs with 6,
12, 24 and 48 dB are connected to the four low pass
sockets at the front panel. In addition it features an
band pass output (i.e. band pass with transistor lad-
der).
The module has manual controls for frequency and
resonance available. Resonance can be adjusted
right up to self-oscillation, in which case the filter will
behave like a sine wave oscillator. Three CV inputs
for frequency control are available. Two of them are
eqipped with attenuators.
The A-108 features an external feedback input that
enables the insertion of additional modules into the
feedback path.
The audio input is very sensitive so that distortion
is possible even with normal A-100 levels.
Audio
In
CV 2
CV 2
Feedb.
CV 3
CV 3 Res.
CV 1
Freq.
Audio Level
6dB
LP
12dB
LP
24dB
LP
48dB
LP BP
A-108
VCF 8