Doepfer A-127 Triple VC Resonance Filter - Manual (Page 5)

doepfer System A - 100 Triple VC Resonance Filter A-127
5
4. Controls
1 Audio In Level
With the attenuator 1 you can set the level of the
audio signals coming in to input ! .
The filter inputs are very sensitive, so it’s possible to
overdrive the Filter with a normal A-100 signal level
(e.g. a VCO). With a VCO being input, overdrive
starts kicking in at about halfway on the attenuator
knob (1)’s travel.
H The module is set up at the factory so that
attenuator 1 doesn’t have any effect on the
Original signal level 8, so the effected sound (3
Filters) and "Original" sound can be controlled
separately, by 1 and 8 respectively (see fig. 1).
It’s possible to change this by altering a jumper
on the mixer circuit board (see chapter 7, Ap-
pendix), so that both the levels (Filter + Original)
can be controlled by attenuator 1 .
2 LFO Frq.
Potentiometer 2 gives control of the LFO frequency.
The frequency of the LFO’s triangle-wave oscillation
can be varied from c. 0.02 Hz (oscillation period c. 1
minute) to c. 20 Hz (oscillation period 1/20 sec).
3 CV Ampl.
The amplitude of the modulation signal is adjusted
with attenuator 3, and the source of this modulation
depends on whether anything is connected to socket
"
.
If the socket has nothing connected, the amplitude of
the internal LFO is controlled; if the socket does have
something connected, the amplitude of the external
control voltage is controlled.
4 LED
LED 4 gives a visual indication of the modulation
signal produced by the LFO.
5 VCF Frq.
Control 5 is used to set the filter frequency f
M
(
range: ~ 40 Hz to ~ 8 kHz).
The actual filter frequency is determined by the sum of
the voltages from the control knob and the modulation
signal (LFO or external control voltage).
6 Resonance
Control 6 is used to set the filter resonance. The
higher this control is set, the narrower the bandwidth
of the bandpass effect (see fig. 1).