12
Dark EnerGy
DOEPFER
Functionality
3.2. The Modules
3.2.1. VCO
The VCO, or alternatively the external audio input, is the source of Dark Energy‘s „raw“ soundmaterial. The
VCO provides the basic waveforms triangle, sawtooth and square with variable pulswidth. The module has
modulation inputs for frequency (pitch) and pulswidth. The frequency range covers approx. 10 Hz to
12 kHz.
The VCO provides the following controls:
• Manual tuning knob
This knob is used for sharp or flat finetuning of the pitch. An internal jumper selects the
range between approx. +/- 1/2 octave or +/- 2,5 octaves. The default setting is +/- 1/2
octave.
• Range switch -1 / 0 / +1 octave
This switch selects the tuning range.
• FM (frequency modulation) knob
This knob is located in the pitch control input of the VCO. It adjusts the pitch modulati
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on depth of a selected modulation source (LFO1 or envelope/ADSR). This knob uses
an exponential characteristic to achive a higher resolution in the lower pitchrange.
• FM Source switch
This switch selects the frequency modulation source of the VCO. The choices are
LFO1, envelope (ADSR) or no source (off). The ADSR generates an „one shot“ pitch
contour, which is characteristic for e.g. certain drum- and percussion-sounds. LFO1
forms a periodic and continous modulation. Low LFO1 frequency settings will result in
vibrati. If LFO1 runs in the audiorange (high), the VCO generates very noisy textures.
• Manual Pulswidth knob
This knob changes the pulswidth of the square signal. Altering the symetry of the
waveform from square to sharp peaks changes it‘s harmonic content and thus the
timbre of the signal. In center position, the VCO provides a rectangular (square) signal
(a). Turning clockwise resp. counterclockwise first narrows the pulses until, at it‘s extre
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me positions, the VCO stopps oscillating and no pulswave signal is audible.
• PWM (Pulswidth modulation) knob
Modulating the pulswidth provides very interesting textures. This knob is located in the pulswidth control
input of the VCO.
It adjusts the pulswidth modulation depth of the selected modulation source (LFO2 or envelope/ADSR).
With high modulation depths and/or narrow pulswidth settings (manual pulswidth knob close to fully clock
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wise / fully counterclockwise), the modulation depth might exceed the maximum value of the pulswidth
range and the waveform will break down. As a result, you will hear dropouts in the audiosignal. This is
normal and can be used creatively as an interesting „gate“-like effekt.
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