A-157 Trigger Sequencer Subsystem

The A-157 Trigger Sequencer is a sequencer with 8 tracks, which, however, does not output adjustable control voltages like the A-155, but only trigger signals – comparable to the two trigger tracks on the A-155. To program when a trigger is to be sent and when not, there are no longer toggle switches like the A-155, but a matrix of status LEDs and touch buttons to switch the respective step on and off.

The system consists of three modules that only work together and are therefore also sold together by Doepfer: There is the actual matrix A-157-1 with 8 tracks and 16 steps, then the 8 trigger outputs – combined in the module A-157-2 and finally the A-157-3 module, which controls the ongoing operation (start, stop, clock, etc.) of the sequencer.

User interface A-157-1




User interface A-157-2



User interface A-157-3






The A-157 modules are almost the perfect way to turn an A-100 system into a programmable running light drum machine. With 8 tracks, however, you will quickly reach your limits with smaller systems: In order to make full use of the 8 tracks, you will also need at least 8 envelopes, tone generators, filters and VCAs (or complete drum modules), which can then be controlled independently by the sequencer. That’s a lot of effort compared to a separate drum computer – even if the sound generation is completely analog. And the external drum machine will usually be much cheaper.

On the other hand, the modular system gives you incomparable flexibility and control, even over the smallest details. What is then often covered with just a single controller on the drum computer can be worked out very finely in detail with entire chains of modules on the A-100. And of course the integration with other parts of the modular system is not to be scoffed at either. In the end it remains a question of philosophy how much control you want to have over seemingly banal things like electronic drums (and their relatives).

Another very worthwhile field opens up with the new polyphonic modules from Doepfer. Instead of just pressing boring chords, you can leave the triggers for e.g. 4 voices to the A-157 and just “play” the harmonic structure of the sequence in real time via the keyboard.

Sound examples

In one of my modular improvisations, “Tat Tvam Asi”, I used the A-157 sequencer not only for “drums”, but in addition to triggering several pre-tuned A-188-1 BBDs, each of which produced a fixed tone using Karplus Strong synthesis. The audio section contains only the tracks controlled by the A-157.

The original of the recording is here:

Technical data (all 3 modules together)

Width52 HP
Depth45 mm
Power requirements350 mA (+12V) / -20 mA (-12V)