Doepfer A-151 Quad Seq. Switch
Four-step sequential signal router for audio and CV
4 HP Eurorack module
The A-151 Quad Sequential Switch is an electronic four-position rotary switch that sequentially connects a common input/output to four individual inputs/outputs with each trigger pulse. It is a versatile utility module capable of switching audio waveforms, CV signals, envelope sources, and filter outputs, making it a powerful tool for creating rhythmic timbral evolution and sequential signal routing.
Features
- Four-position sequential switching of audio and CV signals
- Bidirectional signal switching — works as 1-to-4 or 4-to-1 router
- Trigger input advances step on rising edge
- Reset input immediately returns to step 1 on rising edge
- Four LEDs indicate active in/output at all times
- Version 2 supports full A-100 voltage range -12V to +12V without modification
- Version 1 supports -8V to +8V signal range
- Steps switch (Version 2 only) limits cycle length to 2, 3, or 4 steps
- Can produce audio-frequency modulation when triggered at audio rates
- Compatible with A-129/3 attenuator/offset for signals outside supported range
Controls & Jacks (17)
- O/I — Common bidirectional connection point
- I/O 2 — Second in/output position
- I/O 3 — Third in/output position
- LED 4 — Status indicator for I/O 1 active connection
- Res In — Reset pulse input to return to first position
- Trig In — Trigger pulse input for sequential stepping
- LED 1 — Status indicator for I/O 2 active connection
- LED 2 — Status indicator for I/O 3 active connection
- I/O 1 — First in/output position
- LED 3 — Status indicator for I/O 4 active connection
- I/O 4 — Fourth in/output position
- Steps — Switch to limit number of addressed steps to 2, 3, or 4 (Version 2 only)
- O/I (Common Out/In) — Common bidirectional connection point
- LED 1 (I/O 1) — Status indicator for I/O 1 active connection
- LED 2 (I/O 2) — Status indicator for I/O 2 active connection
- LED 3 (I/O 3) — Status indicator for I/O 3 active connection
- LED 4 (I/O 4) — Status indicator for I/O 4 active connection
How-To Guides
- Sequential VCO Waveform Morphing
- Four-Step Filter Envelope Sequencing
- Sequential Filter Mode Switching
- Sequential CV Source Distribution
- Audio-Rate Waveform Fusion FM
- Rhythmic Gate Distributor
- Odd-Length Sequence via Reset
- Keyboard-Triggered Envelope Progression
- Sequential LFO Waveform Selector
Explore the interactive A-151 Quad Seq. Switch panel on BleepDex — tap any control to learn what it does.
