Doepfer Dark Energy II - Manual (Page 16)

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Dark EnerGy II DOEPFER Functions
to the VCO signals. Signals connected to this socket are fed directly into the filter. The input is mono and
will process levels up to 1Vpp without distortion.
When using an external audio signal please note: Set the waveform switch to „off“ (center position), turn the
PW pot fully clockwise or counter-clockwise and shut off PWM by turning the PWM pot fully counter-clock-
wise if you want the VCO to shut up completely. To make a connected audio signal audible, Dark Energy
II‘s VCA has to be opened. Turn up the VCA pot and / or play a note on your keyboard which will open up
the VCA via a gate signal and ADSR control voltage. Of course you can use the external input and the VCO
in parallel. This way you may add a second VCO (e.g. Doepfer A-110, controlled from the CV1 socket) or a
noise generator (e.g. Doepfer A-117 or A-118) as an additional sound source.
3.2.3. VCA
The VCA produces dynamic control over a third important parameter - loudness or volume. A VCA is a
voltage-controlled amplifier. Dark Energy II uses a VCA with exponential character.
The VCA has the following controls:
• Amplitude control
This pot controls the level of the output signal initially independently from the ADSR /
LFO1 controls. If omly this knob is cranked up, you will hear a static tone which is not
influenced by the envelope or LFO1 settings.
• AM knob (amplitude modulation)
This pot adjusts the depth of loudness modulation by a selected modulation source
(LFO1 or envelope/ADSR). Please note: Above the center position the modulation
depht decreases again. The highest output level with maximum dynamics can be
achieved in settings around the center position. The reason for this effect is quite sim-
ple: The maximum amplification factor of the VCA is „1“. The AM knob value is added
to the amplitude knob value. If the sum of the control voltages is bigger then „1“, they
will get „compressed“ or „flattened“. This will result in a new and different envelope- or
LFO shape with reduced dynamics and – if LFO1 is selected as modulation source
and AM knob is set above 7-8 – in a trapezoid-shape voltage contour. To achieve a
symmetrical LFO modulation, the amplitude knob should be around its center setting.
So, next to the modulation intensity, the VCA knobs can also be „abused“ to shape the
modulation curve to a certain degree.
• AM Source switch
This switch selects the source of the VCA´s amplitude modulation. The switch toggles between LFO1,
envelope (ADSR) and no source (off). The ADSR as AM source produces a „one shot“ loudness contour.
This modulation – do you remember the filter section? - is one of the most important standards in sound
synthesis as it simulates the typical characteristics of the loudness contour of acoustic instruments from
loud to soft. LFO1 again generates periodic modulation. Low LFO1 frequency settings will result in tremolo.
If LFO1 runs at audio rate (high), AM will generate noisy textures not unlike distortion.
• VCA A Input
This socket delivers an input for external CVs to control the VCA amplitude with. This external CV will be
added to the internal CVs provided by LFO1 /ADSR. The external CV is added behind the AM-knob. This
input processes signal levels between 0 Volt and +5 Volts.
• Audio Output
This is where you can tap Dark Energy II‘s output signal from. Maximum level is approx. 1 Vpp.