Doepfer - A-157: Trigger Sequencer
A-157 is a trigger sequencer subsystem that is used to generate up to eight trigger signals controlled by a 8x16 led/button matrix (some customers call it "miniature schaltwerk" as it is based on the same matrix as the no longer available schaltwerk). the system is still in the prototype state. consequently the specifications on this page are still preliminary!
the subsystem will probably contain several modules:
the led/button matrix module a-157-1
the trigger output module a-157-2
one of the control modules (a-157-3, a-157-4 ...)
the led/button matrix module a-157-1 is the core of the subsystem. it is used to set or reset the trigger event on each of the 16 steps of each of the 8 rows. the trigger output module a-157-2 outputs the 8 trigger signals and has an led display for each trigger. we will probably add a mute button or mute switch for each row that allows to turn the trigger output off/on independent for each row. in the final version the modules a-157-1 and a-157-2 will be probably merged into one module only because both modules are essential for the subsystem.
the module a-157-1/2 (or the merged module that will contain both units) can be connected to a simple control module or a more sophisticated control module which is planned for the future (similar to the a-155 and a-154 conceptual design where the a-155 includes a simple control unit that can be replaced by the a-154 which offers a lot of additional functions).
at the beginning a simple control module a-157-3 similar to the a-155 control unit will be available. it offers only the functions clock, start/stop and reset (both with manual controls and control inputs). for this standard control unit the tempo (clock) is the same for all 8 rows, the direction is forward and the length of each row is 16.
we also plan a more complex control module a-157-4 that allows additional functions like 128 memories for trigger sequences, different clock/start/stop/reset for 2 or 4 groups of rows (e.g. common for rows 1-4 and 5-8, or in pairs), independent first/last step for each row, independent direction (forward/backward/pendulum/random) for each row, one-shot mode, lc display and so on. but these ideas are very preliminary and we will have to find out which functions are essential.
this module has a maximum current draw of 350ma. it requires 52 te/hp worth of space to fit in a eurorack frame.