DOEPFER Quad AD/LFO A-143-1 Manual

System A-100 Quad AD/LFO A-143-1
DOEPFER
1. Introduction
Module A-143-1 contains four independent Attack/Decay
generators. When the module is used as a complex
envelope generator, then two, three or four units are daisy-
chained, i.e. the preceding unit triggers the following unit.
But the four units can be used even as four separate AD
generators (mode switch in position AD) or free-running AD-
type LFOs (mode switch in position LFO). The LFO mode
differs in several points from a regular LFO (e.g. A-145, A-
146 or A-147), as the slopes are exponential - in contrast to
linear slopes of a normal LFO. In addition the frequency is
defined by both controls, as the attack control defines the
duration of the rising slope, while the decay control defines
the duration of the falling slope.
Each unit has available a comparator that compares the AD
output voltage against a manually adjustable threshold and
turns on the corresponding comparator output as soon as
the AD output voltage goes below the threshold level during
the decay phase. The comparator outputs are normalled to
the trigger inputs of the following stage via the switching
contacts of the trigger input sockets. Consequently the first
unit triggers the second, the second triggers the third and so
on (and the last unit triggers the first one).
Each AD/LFO unit also offers a polarizer control. This allows
adding or subtracting all AD/LFO signals to the mix output
with adjustable level. Additionally each unit features a single
envelope output and a digital "End Of Attack (EOA)" output,
that indicates the end of the attack phase.
Fig. 1: A-143-1 Controls, Inputs and Outputs
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