Doepfer A-154 User Manual
doepfer
System A - 100
Sequencer Controller
A-154
1. Introduction
Module A-154 is a supplement to the Analog/Trigger
Sequencer A-155. It offers a lot of new features that are
not available in the basic control unit of the A-155. The
A-154 is used to replace the control unit of one or two
A-155, i.e. the section marked "Control" with Start / Stop
/ Step / Reset buttons and inputs in the upper left corner
of the A-155 front panel. If the A-154 is used to control
the A-155 the control section of the A-155 is put out of
action.
These are the most important features of the A-154:
• 5 different running modes: forward, backward, pen-
dulum, random, CV controlled step adressing. All
modes are available as loop or one-shot
• Manual and voltage controlled selection (with at-
tenuator) of the running mode
• 5+1 LED display for the 5 different current modes
and one LED for loop/one-shot display
• Manual and voltage controlled selection (with at-
tenuator) of first and last step of the sequence
• In the "CV Controlled Step Address" mode the First
Step section is used to determine the active sequencer step (in this mode the first/last step feature is not
available). Consequently manual and voltage con-
trolled selection of the active step is possible
• Internal voltage controlled clock generator with
manual and voltage controlled (with attenuator)
clock rate, enables variable time length for each
step, e.g. controlled by one of the analog rows of the
A-155
• Skipping of steps, e.g. the gate row of the A-155 can
be used to control the skipping of steps
• LED display of the clock signal
• Manual and voltage controlled (with attenuator)
pulse length of the clock signal. This features enables different gate length (at the same clock rate) for
each step, e.g. one of the CV outputs of the A-155
can be used to control the PW
• One or two A-155 can be controlled from the A-154
• 8/16 step mode: In combination with two A-155 one
can select between parallel (8 steps) or serial operation (16 steps). The serial operation requires addi-
tional voltage controlled switches (e.g A-150)
• Manual and voltage controlled selection between
"old" control unit of the A-155 and A-154 control
(A-154 Master on/off function)
• With the One-Shot modes the A-155/A-154 combi-
nation can be used e.g. as a complex envelope
generator. One analog row determines the levels of
the envelope. The second analog row can be used to
adjust the time length for each step
• The A-154 requires at least one A-155
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A-154
Sequencer Controller
System A - 100
doepfer
Fig.1: Overall view
2
doepfer
System A - 100
Sequencer Controller
A-154
2. Basic principles
The current step position of the A-155 is determined
by the current address of the sequence. The address
reaches from 1 to 8 as the A-155 has eight steps
available. Internally the address is formed by three
digital address signals A0, A1 and A2 having the
valencies 1 (A0), 2 (A1) resp. 4 (A2). The connection
between step position and the digital values for A0, A1
and A2 is as follows:
Step
position
1 low / 0 low / 0 low / 0
2 high / 1 low / 0 low / 0
3 low / 0 high / 1 low / 0
4 high / 1 high / 1 low / 0
5 low / 0 low / 0 high / 1
6 high / 1 low / 0 high / 1
7 low / 0 high / 1 high / 1
8 high / 1 high / 1 high / 1
A0 A1 A2
The "old" control unit of the A-155 simply generates
the address signals A0, A1 and A2 so that the steps
1-8 are selected one after another. If the A-154 is
used to drive the A-155 the old control unit (i.e. the
section with Start/Stop/Step/Reset buttons and input
sockets) is no longer active and the A-154 calculates
the address signals A0, A1 and A2 in a more sophisticated way. The type of address succession depends
upon the selected mode (forward, backward, pendulum, random, CV addressed, loop/one shot).
In serial mode (i.e. if the A-154 is used to drive two
serial running A-155) another address signal A3 with
valency 8 is generated. This signal is used to distinguish between the first and second A-155 by means
of voltage controlled switches.
In addition the A-154 even generates clock signal with
both voltage controlled rate and pulsewidth.
If the A-154 is used to control the A-155 the previous
connection between the "old" control unit and the
analog resp. trigger/gate rows of the A-155 has to be
disconnected and the rows have to be connected to
the corresponding signals of the A-154. In the appendix this procedure is described in detail. The combination of A-154 and A-155 does not work before this
procedure is carried out. It is not sufficient simply to
assemble the A-154 into the A-100 frame !
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A-154
Sequencer Controller
3. Overview
c
1
a
1
1
System A - 100
a
!
b
6
doepfer
a
&
6
6
6
8
b
b
&
c
&
a
7
c
7
b
/
d
d
&
9
(
2
3
4
5
"
b
2
a
§
b
3
a
$
b
4
a
%
b
5
a
)
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doepfer
System A - 100
Sequencer Controller
A-154
Controls:
1a Manual Mode: Manual Mode control
1b Mode CV: Attenuator for CV input !
1c Mode display (6 LEDs)
2a Manual First: Manual First control
2b First CV: Attenuator for CV input "
3a Manual Last: Manual Last control
3b Last CV: Attenuator for CV input §
4a Manual Clock: Manual Clock control
4b Clock CV: Attenuator for CV input $
5a Manual PW: Manual Pulsewidth control
5bPW CV: Attenuator for CV input %
6a Manual Start: Start button
6b Manual Stop: Stop button
6c Manual Reset: Reset button
6d Manual Clock: Clock button
7a 8/16 Steps: 8/16 steps switch
7b 9-16/A3: LED display of A3/output /
8 Man On/Off: A-154 master switch
9 Clock: Clock display
Inputs / Outputs:
! Mode CV: Mode control voltage input
" First CV: First control voltage input
§ Last CV: Last control voltage input
$ Clock CV: Clock control voltage input
% PW CV: Pulsewidth control voltage input
&a Ext. Start: External Start input
&bExt. Stop: External Stop input
&c Ext. Reset: External Reset input
&dExt. Clock: External Clock input
/ 1-8/9-16: A3 output (1-8 / 9-16)
( ext. Master: External master control input
) Clock Out: Clock output (2x)
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