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DHE Modules

VCV Rack modules from Dale Emery

The Sequencizer User Guide

Sequencizer may seem complex and daunting, but it operates on a small number of powerful, flexible ideas: Phases, anchors, and advancement.

The power of Sequencizer comes from the great flexibility it offers. You can combine these simple ideas to generate an enormous variety of precisely defined control signals to modulate the devices in your VCV Rack patches.

How Sequencizer Works

Step Phases: Generate and Sustain

  1. Generate Phase. Each step starts by generating a signal that progresses from the start anchor voltage to the end anchor voltage. The generate phase always occurs, but may be interrupted by a trigger, depending on the INT control.
  2. Sustain Phase. When a step finishes generating, it optionally sustains at the end anchor voltage until a trigger occurs. The SUST control determines whether a step executes its sustain phase.

Step Anchors: Start and End Voltages

A step generates by interpolating between the voltages of its start and end anchor over its duration. At any moment during the generate phase, the step emits a voltage that is part-way between the voltages reported by these anchors.

An anchor’s voltage is determined by its source and its mode.

Anchor Sources. An anchor can acquire its voltage from several sources, selected by the SOURCE control (the unnamed button above the anchor’s knob):

Anchor Modes. The MODE control (the unnamed button below the anchor’s knob) determines when the anchor acquires its voltage.

In SMPL mode, the anchor samples its source exactly once, at the start of the step, and always reports this sampled voltage. Any changes in the source voltage are ignored by the anchor while the step generates.

In TRACK mode, the anchor tracks its source, and always reports the source’s current voltage.

Moving Targets. Note that if an anchor is tracking its source, the anchor’s voltage can change while a step is active. This means that the voltages between which the step interpolates can both be moving targets.

Advancing from One Step to the Next

The advancement controls determine when the sequence advances from one step to the next.

Triggers. While a step is active (whether generating or sustaining), it watches the state of the GATE, and generates an internal trigger whenever the GATE satisfies the condition specified by the TRIG setting. (RISE, FALL, EDGE, HIGH, or LOW) The INT and SUST controls determine how the step responds to these internal triggers.

Interrupting the Generate Phase. The INT control specifies whether triggers interrupt the step. If INT is ON, a trigger that occurs while the step is generating:

If INT is OFF, the step ignores triggers during its generate phase.

Sustaining. When a step finishes generating, it optionally sustains at the end anchor voltage until a trigger occurs. If SUST is ON when a step finishes generating, the step sustains until a trigger occurs. While it sustains, it emits its end anchor voltage. If SUST is OFF, the step skips its sustain phase, and the sequence immediately advances to the next step.

Techniques

Controlling Advancement

Sequencizer offers great flexibility and control over how a sequence advances from one step to the next.

Technique TRIG INT SUST Image Notes
Externally Clocked any ON ON Advance when the GATE condition is satisfied, regardless of what phase the step is executing. Useful for creating an externally-clocked step sequencer or a sample-and-hold step.
Uninterruptible: Fixed Duration N/A OFF OFF Advance when the generate phase completes, regardless of the condition of the GATE. Useful for hold stages.
Interruptible: Maximum Duration any ON OFF Advance when the generate phase completes or when the GATE condition is satisfied, which ever happens first.
Minimum Duration any OFF ON Complete the generate phase, then sustain until the GATE condition is satisfied.
Skippable LOW ON OFF Advance if the GATE is low at the start of the step or becomes low while the step is active. Useful for configuring a sequence of attack, decay, and sustain stages to jump immediately to the release stage when the GATE falls.
Generate + Sustain LOW any ON Useful to combine decay and sustain in a single step.

Controlling Voltages

A step’s anchors define the voltages between which the step interpolates during its generate phase. Each anchor has two possible modes and five possible sources. This gives 100 possible combinations.

Here are some of the more common configurations.

Technique Start Anchor End Anchor Image Notes
Constant SMPL LEVEL TRACK OUT Emit a specified constant voltage. Useful to create a step sequencer.
Hold SMPL OUT TRACK OUT Hold at the the previous step's final voltage. Useful for envelope sustain and hold stages.
Sample and Hold SMPL any input TRACK OUT Hold at the voltage sampled from an input.
Fixed Ramp or Curve SMPL LEVEL SMPL LEVEL Progress from one specified voltage to another. Useful for an envelope attack stage (0V to 10V).
Continuation Ramp or Curve SMPL OUT SMPL LEVEL Progress from the previous step's final voltage to a specified voltage. Useful for an envelope decay stage (set LEVEL to sustain voltage) or release stage (set LEVEL to 0V).
Passthrough TRACK any input TRACK same input Track and emit an input signal.
Fade In SMPL any source TRACK any input Fade from the sampled voltage to the selected input signal.
Fade Out TRACK any input SMPL any source Fade from the selected input signal to the sampled voltage.
Crossfade TRACK an input TRACK another input Fade from one input signal to another.

NOTE: If you’re surprised by my advice to set the end anchor to TRACK OUT for the constant, hold, and sample and hold techniques, consider: This advice makes it easier to experiment with different start sources. Every time you select a new start source, the end anchor will automatically follow along.

NOTE: If an anchor is set to TRACK its source, the anchor’s voltage can change while the step is active. This means that the voltages between which the step interpolates can both be moving targets. This can create some very surprising, very creative results. Experiment!

Controlling Sequences

Pausing a Sequence. To pause a sequence, turn RUN off.

Resuming a Sequence. To resume a paused sequence, turn RUN on.

Retriggering Envelopes. To retrigger an envelope (that is, to interrupt an in-progress envelope and restart it from the beginning): send a rising edge to both RESET and GATE simultaneously. The rising RESET interrupts the current step, even if it is ignoring the GATE. Then the rising GATE immediately restarts the sequence.

Note that a rising RESET signal takes priority over the steps’ INT settings. As a result, a rising RESET signal interrupts even an “uninterruptible” step.

Examples

Envelope Generator Steps

Attack Stage

Parameter Value Notes Image
TRIG LOW If INT or SUST are ON, experiment with other GATE conditions here. If INT and SUST are both off, this setting does not matter.
INT ON This makes the step interruptible. Set INT OFF to make it uninterruptible.
SUST OFF Variation: To combine the step with a sustain stage, turn SUST ON and set TRIG to LOW.
Start Anchor SAMPL LEVEL The most common start voltage is 0V. Alternatively, use SAMPL OUT to start the attack at the previous step's final voltage.
End Anchor SMPL LEVEL The most common start voltage is 10V.

Hold Stage

Parameter Value Notes Image
TRIG LOW If INT or SUST are ON, experiment with other GATE conditions here. If INT and SUST are both off, this setting does not matter.
INT ON This makes the step uninterruptible. Set INT ON to make it interruptible.
SUST OFF Variation: To combine the step with a sustain stage, turn SUST ON and set TRIG to LOW. This turns it into a "hold for at least the specified duration" stage.
Start Anchor SAMPL OUT To start the release at the previous step's final voltage.
End Anchor TRACK OUT To continue emitting the sampled voltage.

Decay Stage

Parameter Value Notes Image
TRIG LOW If INT or SUST are ON, experiment with other GATE conditions here. If INT and SUST are both off, this setting does not matter.
INT ON This makes the step interruptible. Set INT OFF to make it uninterruptible.
SUST OFF Variation: To combine the step with a sustain stage, turn SUST ON and set TRIG to LOW.
Start Anchor SAMPL OUT To start the decay at the previous step's final voltage.
End Anchor SMPL LEVEL Set the LEVEL to the desired sustain voltage.

Sustain Stage

Parameter Value Notes Image
TRIG LOW The GATE condition that ends the sustain stage.
INT ON Advance if the GATE is low at any point during the generate phase.
SUST ON If the generate phase completes, continue emitting the sampled voltage until the GATE falls.
Start Anchor SAMPL OUT Sample the previous step's final voltage.
End Anchor TRACK OUT To continue emitting the sampled voltage.

Release Stage

Parameter Value Notes Image
TRIG LOW If INT or SUST are ON, experiment with other GATE conditions here. If INT and SUST are both off, this setting does not matter.
INT ON This makes the step interruptible. Set INT OFF to make it uninterruptible.
SUST OFF Variation: To combine the step with a sustain stage, turn SUST ON and set TRIG to LOW.
Start Anchor SAMPL OUT To start the release at the previous step's final voltage.
End Anchor SMPL LEVEL The most common end voltage is 0V.

Step Sequencers

Externally Clocked Step Sequencer

To create a traditional, externally-clocked step sequencer that holds each level until the GATE rises, configure each step liks this:

Parameter Value Notes Image
TRIG RISE RISE is the traditional GATE condition to use here, but you can tune your step sequencer by specifying any condition. And you can use different conditions for different steps.
INT ON Advance if the GATE rises while generating.
SUST ON If the generate phase completes without interruption, sustain until the GATE rises.
Start Anchor SMPL LEVEL Set the LEVEL to the desired voltage.
End Anchor TRACK OUT To continue emitting the same voltage.

The INT and SUST settings cause the step to advance only when the GATE satisfies the TRIG condition, regardless of what phase (generate or sustain) the step is executing. This puts advancement entirely under the control of the GATE.

Timer-Controlled Step Sequencer

To create a timer-controlled step sequencer that holds each level for a specified duration, configure each step like this:

Parameter Value Notes Image
INT OFF Emit the sampled voltage until the timer expires, ignoring the GATE condition.
SUST OFF Advance automatically when the timer expires.
Start Anchor SMPL LEVEL Set the LEVEL to the desired voltage.
End Anchor TRACK OUT Emit a constant voltage.
DUR desired duration The duration of the step's timer.

The INT and SUST settings cause the step to ignore the GATE, putting advancement entirely under the control of the step’s DUR timer.

Sample and Hold Sequencers

Externally-Clocked Sample and Hold Sequencer

To create a multi-step, externally-clocked sample-and-hold sequencer where each step advances on a different GATE condition, configure each step liks this:

Parameter Value Notes Image
TRIG any Different steps can advance on different GATE conditions.
INT ON Advance if the GATE condition is satisfied while generating.
SUST ON If the generate phase completes without interruption, sustain until the GATE condition is satisfied.
Start Anchor SMPL any input Different steps can sample different inputs.
End Anchor TRACK OUT To continue emitting the same voltage.

The INT and SUST settings cause the step to advance only when the GATE satisfies the TRIG condition, regardless of what phase (generate or sustain) the step is executing. This puts advancement entirely under the control of the GATE.

Timer-Controlled Sample and Hold Sequencer

To create a multi-step, timer-controlled sample-and-hold sequencer where each step holds for a different duration, configure each step liks this:

Parameter Value Notes Image
INT OFF Emit the sampled voltage until the timer expires, ignoring the GATE condition.
SUST OFF Advance automatically when the timer expires.
Start Anchor SMPL any input Different steps can sample different inputs
End Anchor TRACK OUT Emit a constant voltage.
DUR desired duration The duration of the step's timer.

The INT and SUST settings cause the step to ignore the GATE, putting advancement entirely under the control of the step’s DUR timer.