doepfer
System A - 100
18dB Low Pass
A-103
3
3. Controls
1
Frq.
With this control you adjust the
Cut-Off Frequency
f
c
,
above which the filter attenuates all frequencies. At 10,
the filter is fully open. The more you turn down this
control, the more the high frequencies are filtered. The
sound becomes mellower and less bright (see Fig. 1)
until at 0 the filter is completely shut, and there will be
no output signal at all.
2
CV 2 •
3
CV 3
For voltage control or modulation of the cut-off fre-
quency, use these CV inputs
"
and/or
§
(see Fig. 1).
Use attenuators
2
and/or
3
to adjust the
control
voltage
level
.
4
Lev.
Use this attenuator to control the amount of signal
entering the filter input
$
.
H
If the filter’s output distorts, turn this control
down, unless you deliberately want the sound
as a spe-
cial effect.
Fig. 1:
Frequency response of the A-103
5
Res.
With this control you adjust the filter’s
resonance
(
emphasis, Q
) - the parameter which emphasises the
frequencies around the cut-off point f
C
. Close to its
maximum setting, the filter becomes so resonant that it
goes into self-oscillation, and starts behaving like a
sine
wave
. You can take advantage of this effect, and use
the VCF as an additional oscillator.
Frq. / CV
Freq.
Res.
Out
f
C
