doepfer-a-151

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.

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