Doepfer A-100(~ 40 MB) - Manual (Page 159)

doepfer System A - 100 VCO 2 A-111
5
Sine wave
Sine waves are pure waves: they just contain the
fundamental, without any harmonics (see Fig. 5).
They are thus not suitable for subtractive synthesis
(shaping sound with a filter) - as there’s nothing to take
away!
Fig. 5: Spectrum of a sine wave
3.2 Frequency Modulation (FM)
Since the frequency of the VCOs can be voltage
controlled, that of course makes frequency modula-
tion (FM) possible. The frequency changes conti-
nuously, depending on the incoming voltages at CV1
and CV2. In contrast with the standard VCO module
(A-110), the A-111 provides two types of frequency
modulation.
For exponential FM (like on the A-110) you simply
input a modulation signal via the normal CV inputs, !
or ". For linear FM there is a dedicated CV input §,
complete with attenuator.
If the modulation signal is in the sub-audio range (for
instance modulation with a slow LFO), there’ll be no
real difference noticeable between the two types. The
result in both cases is a typical vibrato (see Fig. 6).
Fig. 6: Frequency modulation with a slow LFO
(vibrato)
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100%
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Harmonics ➨