Module A-155 (Analog / Trigger Sequencer) is a combined 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 Sequencer 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 pushbutton 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 particularstep.


  • 8 potentiometers (knobs)
  • Lower row: Scale (knob), voltage output range 0 ... ~ +6,5V
  • Upper row: 1V/2V/4V (octave range switch for exact VCO control), voltage output ranges 0 ...1.0V / 0 ...2.0V / 0 ...4.0V
  • Glide time (knob), same as portamento or slew limiter
  • Glide Control (control input for switching glide on/off)
  • S&H Control (control input for internal S&H, works like A-148)
  • Pre Glide/S&H-Out (analog output before S&H and glide unit, especially required when external audio signals are used as inputs of the lower row)
  • Post Glide/S&H-Out (analog output after S&H and glide unit)
  • Lower row: external inputs for the 8 steps (switched jack sockets), control signals or audio signals may be used as inputs (allowed voltage range -5V...+12V), the knobs of the lower row are working in this case as attenuators
  • 4 Trigger/Gate tracks with 2 rows of switches
  • Toggle switches of 1-0-1 type (with middle position), which can be used to send a trigger/gate to the track above or below or to send no trigger/gate (middle position)
  • 3 trigger rows (i.e. short pulse for each step set, pulse width corresponds to the pulse width of the clock/step input signal)
  • 1 gate row (i.e. a high signal is applied during the length of the step set)

ConditionBrand New (New)
Brand New items are sold by an authorized dealer or original builder and include all original packaging.learn more
  • A-155 Analog / Trigger Sequencer
Synth Module Function
  • Sequencer
Modular Synth Format
  • Eurorack

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Burbank, CA, United States
Joined Reverb:2015

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