16
Dark EnerGy
DOEPFER
Functionality
When using an external audiosignal please note: To disable the VCO, put the waveform switch to „off“
(center position), move the PW-knob in fully clockwise or counterclockwise position and shut off PWM by
turning the PWM knob into fully counterclockwise position. To make a connected audiosignal audible, Dark
Energy‘s VCA has to be opened. Crank up the VCA knob and / or play a note on your keyboard, which will
open up the VCA via gate signal and ADSR control voltage. Of course you can use the external input and
the VCO in parallel. So you may add a second VCO (e.g. Doepfer A-110, controlled by the CV1 socket)
or a noise generator (e.g. Doepfer A-117 or A-118) as an additional soundsource.
3.2.3. VCA
The VCA provides dynamic control over a third importand parameter – the loudness. A VCA is a voltage
controlled amplifier. Dark Energy‘s VCA is somewhat special: It‘s characteristics are exponential from
approx. –90 dB to –20 dB and linear between –20 dB and 0 dB. This results in a different and musically
more useful behaviour compared to ordinary VCAs.
The VCA provides the following controls:
• Amplitude knob
This knob controls the level of the outputsignal initially independent from the ADSR /
LFO1 controls. If only this knob is cranked up, you will hear a static tone, not yet
influenced by the envelope or LFO1 settings.
• AM knob (amplitude modulation)
This knob adjusts the loudness modulation depth of 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: The
maximum amplification of the VCA is factor „1“. The AM knob value is added to the
amplitude knob value. If the sum of the control voltages becomes greater then „1“,
they get „compressed“ or „flattened“. This results 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 shaped 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
modulationcurve to a certain degree.
• AM Source switch
This switch selects the source for the amplitude modulation of the VCA. The switch toggles between LFO1,
envelope (ADSR) and no source (off). The ADSR as AM source provides a „one shot“ loudness contour.
This modulation – you may remember the filter section – is one of the most importand standarts in sound
-
synthesis, since it simulates the typical characteristics of the loudness contour of acoustic instruments from
loud to soft. LFO1 again generates periodic modulations. Low LFO1 frequency settings will result in tremoli.
If LFO1 runs in the audiorange (high), AM generates noisy textures.
• VCA A Input
This socket provides an input for external CVs to control the VCA amplitude. This socket is normalised, that
means that a plug disconnects the ADSR or LFO1 from the VCA control input in place of the external CV.
The modulationdepth is again controlled with the AM knob. This input processes signal levels between 0
Volt and +5 Volt.
Again, this CV is added to the internal CV provided by the AM knob.
• Audio Output
Here you can pick up Dark Energy‘s output signal. Maximum level is approx. 1 Vpp.
