Doepfer Dark Energy I (device no longer available) - Manual (Page 26)

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Dark EnerGy DOEPFER Basics of Soundgeneration
4. Basics of Soundgeneration
In case analogue synthesizers or synthesizers in general are new to you, please read this section. You may
learn some basics about analogue / subtractive soundsynthesis that will help you to fully understand Dark
Energy’s little secrets.
Sound is, very generally spoken, a change of air pressure. If these chang-
es happen continously and with a certain frequency, they can become an
audible noise or tone. Frequency is measured in Hertz (Hz). The human
ear percepts frequencies approx. between 20 Hz and 20.000 Hz. The
frequency of an audible signal determintes it’s musical pitch.
Another basic parameter that is percepted by our ears is loudness resp.
the level of an audible signal. Loud tones or noises move more air than
weak ones. Thus, the “size” of the signal is called amplitude and is mea-
sured in Dezibel (dB).
The third importand parameter to define a sound is the timbre. The is no special definition, it is usually
described with associative terms, such as sharp, dull, bright, dark, thin or rich.
The timbre is determined by the so called overtone content of the sound. In general, bright sounds contain
more overtones, dull sounds lesser.
As we see, the “raw material” of a sound is defined by the three parameters frequency or pitch, loudness or
level and timbre resp. overtone content.
Oscillators and Waveforms
With analog synthesizers the tonal “raw material” is produced by voltage-controlled oscillators (VCOs). Nor-
mally, a VCO provides several waveforms. Standard waveforms are pulse, sawtooth and triangle. These
are most useful in soundgenaration, since they offer a rich but different overtone content and therefor they
sound very different from each other. Thus Dark Energy uses them. Less used waveforms (sine, spaced
sawtooth, graphically editable wave forms) are not dealt with here.
As said above, the waveforms differ in their overtone spectrum, i.e. they contain different harmonics. An
overtone is called harmonic if its frequency is an integer multiple (2, 3, 4, ...) of the base tone frequency.
A sawtooth wave contains all harmonics with descending
amplitudes.
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%