A-155 Analog Trigger Sequencer (Used)

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 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.

This used module is in good condition with some rack rash.