doepfer/a-151

A-151 Quad Sequential Switch

Electronic four-position rotary sequential switch with trigger and reset inputs, four bidirectional I/O jacks, a common Out/Input, four LEDs indicating the active step, and a toggle switch to limit steps to 2, 3, or 4.527

Capabilities 2

Sequential Switchsequential-switch: Clock-stepped four-position rotary switch that connects one common O/I jack to each of four I/O jacks in sequence on each trigger pulse. Bidirectional; can operate as 1-to-4 demultiplexer or 4-to-1 multiplexer.527
Signal Switchsignal-switch: 527

Jacks 7

Name	Signal	Voltage	Description
Inputs (7)
Common	mixed	-8V to 8V	Common out/input (O/I); the shared bidirectional node that steps through the four I/O jacks. Accepts audio, CV, gate, trigger, or clock signals.527
I/O 1	mixed	-8V to 8V	Bidirectional in/output 1; connected to the common O/I when active step is 1.527
I/O 2	mixed	-8V to 8V	Bidirectional in/output 2; connected to the common O/I when active step is 2.527
I/O 3	mixed	-8V to 8V	Bidirectional in/output 3; connected to the common O/I when active step is 3.527
I/O 4	mixed	-8V to 8V	Bidirectional in/output 4; connected to the common O/I when active step is 4.527
Reset	trigger	—	Reset input; a rising-edge pulse immediately returns the common out/input to in/output 1.527
Trigger	trigger	—	Trigger input; each rising-edge pulse advances the common out/input to the next in/output.527

Parameters 1

Name	Type	Range	Behavior
Steps	switch	2 – 4	Limits the number of sequentially addressed in/outputs to 2, 3, or 4. Available only in version 2 of the module (from approximately 2005).527

Firmware history 0 versions

No firmware history recorded.

References 2

[527]
Doepfer A-151 Quad Sequential Switch manual (English)manual
source 527 canonical ↗ archived ↗

● verified 2026-05-19
[528]
Doepfer A-151 Quad Sequential Switch product pageproduct_page
source 528 canonical ↗ archived ↗

● verified 2026-05-19