doepfer
System A - 100
Analog / Trigger Sequencer
A-155
1
1. Introduction
Module
A-155
(Analog / Trigger Sequencer) is a com-
bined
8-step
analog and trigger sequencer
: it can
simultaneously produce sequences of analog voltages
and trigger and/or gate signals.
Module A-155 works very much like the Clock Sequen-
cer module, A-161, but includes many extra (and
expensive to implement!) functions.
The
control section
includes switches for
Start
,
Stop
,
Step
and
Reset
- which can be operated by
push-
button
as well as
digital signals
. Above the top row,
eight LEDs
show the progress of the sequence, with
each step’s LED lighting in turn.
The A-155 has two
analog rows,
each with
eight
knobs
, with which to set the control voltage for each
step. The upper row is particularly designed for pitch
control of a VCO, with a
range switch
giving the ability
to set pitches precisely.
The lower row of eight knobs has the ability to accept
an
external signal for each step
, in which case the
knobs act as attenuators for this voltage.
The variable voltages from the analog rows can either
be output direct, or can go through a
sample-and-
hold
section and a
slew limiter (‘glide’).
Using the
S&H
and
glide control inputs,
it’s possible to select
‘hold’ (S&H) or portamento (glide)
for whichever step
or steps you want.
Three rows
of
triggers
and
one row
of
gates
are
available. For each step, a three-way mini-switch lets
you decide whether one or the other (or neither) of the
two triggers works. Each row has an
LED
which lights
whenever a trigger or gate is active at any particular
step.