Doepfer Dark Energy II - Manual (Page 12)

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Dark EnerGy II DOEPFER Functions
3.2. The Modules
3.2.1. VCO
The VCO, or alternatively the external audio input, is the source of Dark Energy II‘s sonic „crude material“.
The VCO produces the basic waveforms triangular, sawtooth, and square wave with variable pulsewidth.
The module has modulation inputs for frequency (pitch) and pulsewidth. The frequency range covers
approx. 10 Hz to 12 kHz.
The VCO has the following controls:
• Manual tuning control
This pot is used for sharp or flat fine-tuning of the pitch. An internal jumper selects the
range of the pot between approx. +/- 0.5 octave or +/- 2.5 octaves. The default setting
is +/- 0.5 octave.
• Range switch -1 / 0 / +1 octave
This switch selects the tuning range.
• FM (frequency modulation) control
This pot is located in the pitch control input section of the VCO. It adjusts the pitch mo-
dulationdepth of the selected modulation source (LFO1 or ADSR envelope). This pot
has exponential response to yield a higher resolution in the lower pitch range.
• FM Source switch
This switch selects the frequency modulation source of the VCO. The choices are
LFO1, envelope (ADSR), or no source at all (off). The ADSR generates a „one shot“
pitch contour, which is characteristic of e.g. certain drum- and percussion-sounds.
LFO1 produces a periodic and continuous modulation. „Low“ frequency settings of
LFO1 will produce vibrato. If LFO1 runs at audio rate (high), the VCO will generate
quite noisy textures.
• Manual Pulsewidth control
This pot changes the pulsewidth of the square wave. Altering the symmetry of the
waveform from wide to narrow square alters its harmonic content and thus the
timbre of the signal. In center position, the VCO produces a rectangular (square) signal
(a). Turning clockwise or counter-clockwise respectively first narrows the pulsewidth
until, at its most extreme setting, the VCO stops oscillating and no pulse wave signal is
audible anymore.
• PWM (Pulsewidth modulation) control
Modulating the pulsewidth creates very interesting textures. This pot is located in the pulsewidth control in-
put section of the VCO. It adjusts the pulsewidth modulation depth of the modulation source selected (LFO2
or ADSR envelope.) At high modulation depths and/or narrow pulsewidth settings (manual pulsewidth
control close to fully clockwise / fully counter-clockwise), the modulation depth might exceed the maximum
value of the pulsewidth range and the waveform will become inaudible. As a result, you will hear drop-outs
in the audio signal. This is perfectly normal and can be used creatively as an interesting „gate“-like effect.
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