Doepfer Dark Energy I (device no longer available) - Manual (Page 15)

15
Dark EnerGy DOEPFER Functionality
• XM Source switch
This switch selects the source for exponential modulation of the cutoff frequency. The switch toggles bet-
ween LFO2, envelope (ADSR) and no source (off). Controlling the cutoff frequency with the ADSR is one
of the most commen modulations, since it provides simulation of the typical characteristics of most acoustic
instruments timbres from bright to dull. Of course Dark Energy‘s envelope generator provides much more
ways to shape the timbre.
LFO2 forms a periodic and continous modulation. Low frequencies provide vibrati in timbre. Using the LFOs
high range, XM generates very noisy sounds that cannot be played tonally. This way of modulation is great
for unique and interesting soundeffects. Feel free to experiment with the settings of cutoff frequency, LFO2
speed and XM knob.
• LM knob
This knob sets the modulation depth of the linear frequency modulation - a very special feature on analogue
synthesizers. Modulation source is always the VCO trianglewave signal. In contrast to exponential FM,
linear FM allows tonally playable sounds, as long as VCF cutoff and VCO signal run in certain frequency
proportions. Highly interesting sounds can be achieved with the selfoscillating filter (high resonance set-
tings). Feel free to experiment with cutoff frequency, resonance, VCO tuning and LM knob setting. Please
note that even small parameter changes can result in drastic new timbres.
• Resonance knob (Res)
This knob sets the resonance intensity of the filter. This effect depends a lot on the cutoff setting and is
most intense at Freq. knob settings between 1 and 5. At high resonance settings, the filter starts to self
oscillate and generates a waveform close to a sine wave. It can be used as an additional signal source to
provide certain popular sound effects, e.g. typical synthesizer percussion sounds when the cutoff is modu-
lated with a suitable ADSR setting.
• When the filter is self oscillating (high resonance) and the VCO is disabled (waveform switch in center po-
sition and PW knob in fully clockwise or counterclockwise position), the filter runs as a sinewave oscillator
and can be linear modulated by the VCO and exponential modulated by LFO2 at the same time! The VCO
frequency can follow the filter cutoff. Very complex sounds are possible.
• Tracking switch
The tracking switch has the positions „half / off / full“. It determines, if or how much the filter cutoff depends
on the played notes (resp. VCO pitch). When set to „full“, higher notes sound more and more brighter, lower
notes more and more dull. This fits to the typical character of acoustic instruments. When set to „half“, this
effect is weaker. If the filter is self oscillating and should be played tonally as an oscillator via MIDI key-
board, this switch has to be set to „full“. So it recieves the same control voltage as the VCO. This setting is
also useful when linear frequency modulation (LM) is used with the self oscillating filter.
• VCF F Input
To modulate the filter cutoff frequency with an external control voltage or an external audiosignal, please
use this socket. This input also uses an (exponential) 1V/Oct scaling. So the self oscillating VCF can be
played (almost) tuned in half tones (the scaling is not as precise as the VCO because of technical reasons
but much better as found in many other analogue synthesizers). The control voltage fed into this input is
added to the internal CVs (Freq. knob, tracking switch, XM knob). Please note, that the sum of these CVs
cannot exceed the maximum value of the modulation depth range.
• Ext. Audio Input
It can be very interesting and musically useful to process external audiosignals, such as acoustic instru-
ments, drumloops or even complete tracks, with the components of a synthesizer. You guessed it – Dark
Energy offers an input socket for external audiosignals, that can be used as a sound source next to the
VCO signals. Signals connected to this socket are fed directly into the filter. The input is mono and proces-
ses levels up to 1Vpp without distorsion.