Doepfer A-100(~ 40 MB) - Manual (Page 376)

A-137 Waveform Multiplier System A - 100 doepfer
2
2. Basic principles
The signal is processed by a standard linear VCA and 4
so-called wave folding stages. The amplification of the
VCA is identical with the Multiples parameter. This is the
working principle of the folding stages: As soon as the
signal goes beyond the upper resp. below the lower
folding level the signal is reflected resp. folded back. The
values for upper and lower folding level are derived from
the input parameters folding level and symmetry. Both
can be adjusted manually and controlled by an external
control voltage (CV). Folding Level determines the di-
stance between the upper and lower folding level, Fol-
ding Symmetry the position of both levels relating to the
zero line. The internal upper and lower folding level are
calculated by adding resp. subtracting the voltages for
Folding Level and Folding Symmetry (refer to fig. 3).
The working principle of one stage by means of a
triangle signal is shown in fig. 1. The upper picture
shows the incoming signal. The areas to be reflected are
filled black. The lower picture shows the output signal of
the stage. In this example the symmetry is slightly posi-
tive and the reflected areas are not symmetrical.
Fig. 2 shows the folding function of three stages. The
amplification (i.e. the Multiples parameter) is increased
for the succeeding pictures to see the effect of incre-
asing Multiples. Stage 4 is not shown because of clear-
ness.
Fig 1: Folding function for one stage
Fig 2: Folding function for three stages