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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 sequen-

cer 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 enab-

les 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 ope-

ration (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

Summary of content (16 pages)

PAGE 1
doepfer System A - 100 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.
PAGE 2
A-154 Sequencer Controller System A - 100 Fig.
PAGE 3
System A - 100 doepfer 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).
PAGE 4
A-154 Sequencer Controller System A - 100 doepfer 3.
PAGE 5
System A - 100 doepfer Sequencer Controller A-154 Controls: Inputs / Outputs: 1a Manual Mode: Manual Mode control ! Mode CV: Mode control voltage input 1b Mode CV: Attenuator for CV input ! " First CV: First control voltage input 1c Mode display (6 LEDs) § Last CV: Last control voltage input 2a Manual First: Manual First control $ Clock CV: Clock control voltage input 2b First CV: Attenuator for CV input " % PW CV: Pulsewidth control voltage input 3a Manual Last: Manual Last control
PAGE 6
A-154 Sequencer Controller System A - 100 4. Controls 1a Manual Mode (knob)/ 1c Anzeige (LEDs) ! Mode CV (socket) / 1b Mode CV (knob) Control 1a is used to select the desired mode manually. This parameter can also be modulated with an external control voltage (CV) applied to socket ! (e.g. slow LFO, foot controller, Theremin). Control 1b is used to attenuate the external CV and consequently the influence of the external CV. The current mode is displayed by means of the 6 LEDs 1c.
PAGE 7
doepfer System A - 100 2a Manual First (knob) 2b First CV (knob) / " First CV (socket) 3a Manual Last (Regler) 3b Last CV (knob) / § Last CV (socket) This group of elements is responsible for the First and Last step of the sequence. For both parameters a manual control (knobs 2a and 3a) and an external control voltage input (CV inputs " and §) are available. The CV inputs are equipped with attenuators (knobs 2b and 3b).
PAGE 8
A-154 Sequencer Controller System A - 100 Another example is to control the clock rate by one of the A-155 CV outputs. This leads to a different time length (or different tempo) for each step, i.e. the tempo is different for each step. If the A-155 Gate output is used to control the clock rate skipping is possible as beyond a certain control voltage the step time becomes extremely short (less than a millisecond) and the corresponding step is practically leaved out.
PAGE 9
doepfer System A - 100 Operating the reset button prepares the sequencer to jump to the first step as soon as the next clock signal (!) appears. If no clock signal is applied the reset button seems not to work! We believe that it makes more sense to carry out the jump to the first step not until the next positive clock transition occurs. Otherwise the next clock would cause an advance to step 2 (in forward mode and first step =1).
PAGE 10
A-154 Sequencer Controller System A - 100 Fig. 2 shows how to patch the upper trigger rows and the upper CV rows of two A-155 with A-154 and A-150. Fig.
PAGE 11
doepfer System A - 100 The position of switch 7a determines if the A-154 manages 8 or 16 steps. Only in position "16" the additional address signal A3 is generated that is required to control the VC switch A-150. In position "8" all functions (e.g. first/last step, CV addressing) are calculated for sequences with up to 8 steps only and the output A3 is permanently "low". In position "16" all functions are calculated for sequences with up to 16 steps and output A3 specifies if address 1...
PAGE 12
A-154 Sequencer Controller 5.
PAGE 13
doepfer System A - 100 Sequencer Controller A-154 Appendix: Connection A-154 – A-155 (1) Disconnect the 10 pin ribbon cable leading from the connector ST1 of the small A-155 controller board to the bus board. This cable is no longer required. But you may keep it as a bus cable replacement (for other modules with 10 pin connectors). (2) Disconnect the 10 pin ribbon cable leading from the connector ST2 of the small A-155 controller board to the other boards of the A-155 (potentiometer and trigger boards).
PAGE 14
A-154 Sequencer Controller System A - 100 doepfer Two 10 pin ribbon cables come from the A-154. One (A) with a 10 pin female connector (A1) at its end and another (B) with two female connectors equipped with pin headers (B1, B2).
PAGE 15
System A - 100 doepfer Sequencer Controller A-154 (4) Connect B1 with the female connector at the end of the ribbon cable that was removed from ST2 of the small A155 controller board (this cable leads to the potentiometer and trigger boards of the A-155). The male pin header inserted into female connector B1 is used to establish this connection.
PAGE 16
A-154 Sequencer Controller System A - 100 doepfer In case that two A-155 have to be controlled by the A-154 the second A-155 has to be connected in this way: Carry out steps (1) and (2) as described above even for the second A-155. Step (3) is not applicable. Step (4) is carried out as described above but B2 is used instead of B1. For this the "blind" female connector has to be removed before the cable coming from the potentiometer and trigger boards of the second A-155 is connected to B2.