Doepfer A-100(~ 40 MB) - Manual (Page 127)

doepfer System A - 100 6/12/24/48 dB Low Pass A-108
5
4. In / Outputs
! Audio In
This is the filter’s audio input socket. Patch in the
output from any sound source (eg. VCO, noise gene-
rator, subharmonic oscillator, sampler, mixer output).
" BP • 6db LP • ... • 48db LP
The sockets " are the filter outputs with the filter
types band pass (BP) as well as 6, 12, 24 and 48 dB
low pass (LP).
H You may change the factory settings of the
cut-off slopes (6, 12, 24, 48 db) for the four low
pass outputs (see chapter 6 for details).
§ CV 1 • CV 2 • CV 3
The sockets CV1, CV2 and CV3 are control voltage
inputs to control the filter frequency. Input CV1 has
no attenuator and works approximately to the 1V/
octave standard (not as exactly as the VCOs). Inputs
CV2 and CV3 are equipped with the attenuators 2 and
3
so that the sensitivity of these inputs can be adju-
sted. With attenuators set to 10 (fully clockwise) the
sensitivity for CV2 and CV3 is about 0.5V/octave.
If you patch one or more modulation sources (e.g.
LFO, ADSR, Random, S&H, Theremin, Ribbon, MIDI-
to-CV) to these inputs, the cut-off frequency of the
filter will be modulated by the sum of the control
voltages: i.e., the sound color changes according to
the sum of the control voltages put out by the modula-
tors.
P If you use the VCF as a sine wave oscillator, it
is recommended to connect the pitch CV to
socket CV1 as this input works approximately
to the 1V/octave standard. Do the same if you
want the filter’s cut-off frequency to track ex-
actly with the pitch of a note.
$ Feedb.
Module A-108 has available an external audio input
for resonance. This socket is normalled, i.e it is
connected to the 48 dB low pass output unless another
signal is patched into this socket. Different modules
can be inserted into the feedback loop (see chapter 5
for examples). E.g. inserting a VCA enables voltage
controlled resonance. It is also possible to feed back
other filter outputs than the 48 dB low pass to obtain
another resonance behaviour.