Manual

Synthesizer Voice A-111-5 System A-100 DOEPFER
14
In addition to the internally generated frequency of the filter
the control voltage applied to the "VCF F" socket
3 modulates the frequency of the VCF as described in
chapter 3.
The LM control 10 is very unusual for a filter. The position
of this control defines the intensity of the internal linear
frequency modulation of the VCF by the triangle of the VCO.
This feature is very useful for FM sounds with the VCF as
sine oscillator (self-oscillation) that keep their harmonic
content while the sound is played e.g. by a sequencer,
keyboard or Midi/USB interface. If the tracking switch 8 is
set to full the VCF tracks to the VCO and if linear FM is
added the overtone structure remains almost unchanged.
11 VCF Resonance
With this control the Resonance or Emphasis of the filter is
adjusted. This function emphasises the frequencies around
the cut-off frequency. Close to the maximum position, the
filter goes into self-oscillation. In this mode it behaves like a
sine wave oscillator, and can be used as an alternative
sound source. A detailed description of the resonance
function can be found in the user manuals of the A-100 filter
modules (e.g. A-120 or A-121).
As the control scale of the VCF in the A-111-5 has a very
precise 1V/Octave behaviour the filter can be "played" over
several octaves like a VCO if it's in self-oscillation. It's not as
precise as a VCO but much better than most other filters.
Especially in combination with the linear FM (LM) very
interesting sounds can be obtained, which are not possible
with other filters.