Doepfer Dark Energy II - Manual (Page 26)

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Dark EnerGy II DOEPFER Nuts and Bolts of Sound Generation
4. Nuts and bolts of sound generation
In case analog synthesizers – or synthesizers in general – are new to you, please read this section thor-
oughly. You will learn about the nuts and bolts of analog / subtractive synthesis that will help you to fully
grasp Dark Energy II’s little secrets.
Sound is, very generally speaking, a change in air pressure. If these
changes occur continuously and at a certain frequency, they can become
an audible noise or tone. Frequency is measured in Hertz (Hz). The hu-
man ear can perceive frequencies from about 20 Hz to 20,000 Hz. The
frequency of an audible signal determines its musical pitch.
Another fundamental parameter that is perceived by our ears is loudness,
that is the level of an audible signal. Loud noises shift more air than soft
ones. Thus, the “size” of the signal is called amplitude and is measured in
Decibels (dB).
The third important parameter which defines a sound is timbre. There is no specific definition as such, it is
usually described in terms like “sharp”, “dull”, “bright”, “dark”, “thin”, or “rich”.
Timbre is determined by the so-called harmonic spectrum of the sound. In general, bright sounds contain
more harmonics, dull sounds less.
As we will see, the “crude material” of a sound is defined by three parameters, namely frequency, ampli-
tude, and timbre.
Oscillators and Waveforms
On analog synthesizers, the timbral “crude material” is produced by voltage-controlled oscillators (VCOs).
Normally, a VCO creates waveforms with varying overtone spectra. Standard waveforms are pulse, saw-
tooth and triangular. These are most useful in sound synthesis as they each offer a rich but different har-
monic spectrum, and therefore they sound very different from each other. That is why Dark Energy II makes
use of them. Less useful waveforms (sine, spaced sawtooth, graphically editable waveforms) will not be
discussed here, let alone, used.
As mentioned above, waveforms differ in their harmonic spectrum, i.e. they contain different harmonics. An
overtone is called “harmonic” if its frequency is a proper multiple (2, 3, 4, ...) of the fundamental frequency.
A sawtooth wave contains all harmonics with descending
amplitudes. Dark Energy II’s oscillator generates two different
sounding types of saw waveforms.
Zeit
ein Schwingungsdurchgang
A
mplitude
Frequenz in Hertz (HZ) =
Schwingungen
Sekunde
Time
One Cycle
Frequency in Hertz (Hz) =
Cycles
Seconds
Zeit Pegel/A
mplitude
Level/Amplitude
Time
f
1
f
2
f
3
f
4
f
5
f
6
f
7
f
8
ff
9
Harmonics
0%
100%