ImpromptuModular

Virtual Eurorack Modules for VCV Rack


Project maintained by MarcBoule Hosted on GitHub Pages — Theme by mattgraham

Virtual Eurorack modules for VCV Rack, available in the plugin library. Version 1.1.9.

Feedback and bug reports (and donations) are always appreciated!

Modules

Each module is available in light (Classic) or dark (Dark-Valor) panels, selectable by right-clicking the module in Rack.

Recommended reading:

The table below shows a comparison of the features available in the Impromptu sequencers.

  WriteSeq32/64 PhraseSeq16 PhraseSeq32 GateSeq64 Foundry BigButton1/2
Configuration* 3x32 / 4x64 1x16 1x32, 2x16 4x16, 2x32, 1x64 4x32 6x64 / 6x128
Clock inputs 1 / 2 1 1 1 4 1
Outputs CV+gate CV+2gates CV+2gates Gate CV+gate+ CV2 Gate / Gate+CV
Patterns per track/ channel 1 16 32 32 64 2 (banks)
Song length - 16 32 64 99 -
Seq. repetitions - FWD 2,3,4 FWD 2,3,4 FWD 2,3,4 0 to 99 -
Gate types 2 12 12 8 12 1
Probability No Global Global Per step Per step No
Slide No Global Global - Per step - / No
Edit while runnning Gates only Yes Yes Yes Yes Yes
Portable sequence - Yes Yes - Yes - / Yes

* Configuration is noted as follows: Channels/Tracks x Sequence-Length. The distinction between channels and tracks relates to clock inputs: when channels are separately clockable they are referred to as tracks.

Known issues

For sequencers and clock modules, it is advisable to have a Audio module added to your patch and assigned to a sound device in order for the timing and response delays in the user interface to be of the proper duration. This is a known artifact in VCV Rack.

License

Based on code from the Fundamental and Audible Instruments plugins by Andrew Belt and graphics from the Component Library by Wes Milholen. See LICENSE.md for licenses (and ./res/fonts/ for font licenses).

Acknowledgements

Impromptu Modular is not a single-person endeavor. Many people have taken the time to suggest improvements and to collaborate on module concepts, graphics, testing, etc. This list of acknowledgements is too large to maintain properly, and so in place of a detailed list of names and participations, I would simply like to extend a big thank you to all that have helped and contributed to the project. The Dark-valor graphic theme was graciously provided by Xavier Belmont.

General Concepts

Many Impromptu Modular sequencers feature a CV input for entering notes into the sequencers in a quick and natural manner when using, for example:

Such sequencers have two main inputs that allow the capturing of (pitch) CVs, as follows: The edge sensitive WRITE control voltage is used to trigger the writing of the voltage on the CV IN jack into the CV of the current step. Any voltage between -10V and 10V is supported, and when a sequencer displays notes via a built-in keyboard or a display showing note letters, non-quantized CVs are mapped to the closest note but are correctly stored in the sequencer.

When AUTOSTEP is activated, the sequencer automatically advances one step right on each write. For example, to automatically capture the notes played on a keyboard, send the midi keyboard’s CV into the sequencer’s CV IN, and send the keyboard’s gate signal into the sequencer’s Write input. With Autostep activated, each key-press will be automatically entered in sequence. An alternative way of automatically stepping the sequencer each time a note is entered is to send the gate signal of the keyboard to both the write and “>” inputs.

A concept related to AutoStep, which is called “AutoSeq when writing via CV inputs”, can be used to automatically change to the next sequence when a write operation reaches the end of the current sequence. Without this, the writing operations loop back over to the start of the current sequence (default behavior). This can be used to turn the sequencers into very long stepped CV recorders (1024 steps in the case of PhraseSeq32 and GateSeq64).

All edge sensitive inputs have a threshold of 1V. In all sequencers, the duration of the gates normally corresponds to the pulse width (high time) of the clock signal. When sequencers offer an Advanced gate mode and this mode is activated, the pulse width of the clock signal has no effect on the sequencer.

In all sequencers, clicking Randomize in the right-click menu of the module will only serve to randomize the content (CVs, gates, slides, etc., as applicable) of the current sequence. For sequencers with a song mode, no song content is randomized when in SONG mode.

Sequence selection via CV inputs

Many sequencers feature SEQ# CV inputs, which can be used to select the active sequence for editing or to externally control the playing order of the sequences. Three different modes are available for these inputs in the right click menu of the modules, under Seq CV in.

This feature can be used to play difference sequences consecutively under external control, without using the built-in song mode in those sequencers.

Expanders

A few of the modules feature Expander modules to provide additional functionality via CV inputs or other controls. An expander modules must be added to the right side of the mother module with no space between the two modules. Expanders automatically match their mother module’s panel theme, thus they do not have a panel theme option in their right-click menu. Only compatible expanders will work with a given module. For example, the PS-X expander will only work with the PhraseSeq16 and PhraseSeq32 modules, while the GS-X expander will only work with the GateSeq64 module.

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Pictured above are the expanders for the following modules, from left to right: Clocked, ChordKey, PhraseSeq16/32, GateSeq64, Foundry.

The FourView module, which is normally used independently, can also be used as an expander for the ChordKey and CVPad modules. When both the ChordKey expander and FourView are to be used with ChordKey, the FourView module must be placed to the right of the ChordKey expander.

On resets, clocks and run states…

Impromptu sequencers implement two particular mechanisms related to resets and clocks in order to ensure proper reset behavior and correctly played first steps/beats.

The following recommendations should also be followed in order to ensure proper reset and first-step behavior in Impromptu sequencers. In all cases, it is assumed that a reset cable is connected from Clocked to the sequencer.

When Clocked is used with sequential switches or other non-Impromptu sequencers, and first steps are not playing correctly upon reset, the following guidelines may be of help:

  1. The option “Outputs reset high when not running” should ideally be in its defaut state in Clocked (i.e. checked), but ultimately the user should experiment with both settings to see which one works best for the setup and modules being used.

  2. The reset and clock signals coming from Clocked should preferrably not pass through any other module and should be connected directly to the sequencer or sequential switch.

  3. If a clock (or reset) signal must be routed through another module (for example, a separate clock divider, a switch, etc.), both the reset and clock signals should be similarly delayed (possibly by using utility modules), such that a reset does not arrive at the sequencer or switch before any clock edges that are produced as a result of that reset event.

Further information for developpers is available in a short summary of the code structure used in Impromptu sequencers, relating to clocks, resets and run states.

Portable sequence

The Portable sequence standard is supported in the following Impromptu sequencers: PhraseSeq16/32, SMS16 and Foundry. Sequences can be copied to the clipboard to then be pasted in any compliant sequencers that support the standard. These special copy/paste commands can be found in the module’s right-click menu under the entry called “Portable sequence”.

The Portable sequence standard can also be used to copy small sequences of up to four notes into/from ChordKey, in order to make a chord out of a sequence of notes, or vice versa. The FourView module also allows the copying of the displayed notes for then pasting as a small sequence in a sequencer, or as a chord in ChordKey.

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Limitations: As a general rule, the Impromptu sequencers are not as expressive as timeline-based sequencers, so it can be anticipated that some features of the sequence will be pruned or quantized. In other words, the finest supported resolution is the quarter note (i.e. a step) and any content with finer musical resolution will be temporally quantized to quarter notes. The advanced gate types are not use to create eighth notes, for example, since no assumption regarding clock resolution can be made when pasting into the receiving sequencer. Tied steps are automatically set during a paste operation to produce half notes or anything longer that quarter notes. Rack’s log file can be used to identify major problems with pasting operations. Polyphony is not supported, and the copy/paste operations are only available when the sequencers are in SEQ mode (as opposed to SONG mode).

Module manuals

The following sections contain more information on how each module works.

BigButtonSeq

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A 6-channel 64-step trigger sequencer based on the infamous BigButton by Look Mum No Computer. Although this is not a direct port of the original module, the intent was to keep it as faithful as possible, while adding a few minor extras such as CV inputs and displays. For two-handed control of the knobs and buttons, connect the sequencer to a midi control surface using Rack’s Core MIDI-CC module. To see more examples of what the sequencer can do, please see the following videos:

Here are a few more details on some of the uses of the buttons. The sequencer uses has two types of push-buttons, namely trigger buttons and state buttons. Trigger buttons react to the change in a button’s state as it’s being pressed, while state buttons react to the position of the push-button, i.e. pressed or not pressed.

Here is a summary of how SNAP and the Big and Del on next step option work.

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BigButtonSeq2

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A 6-channel 128-step gate and CV sequencer based on BigButtonSeq. Familiarity with that sequencer is recommended since only the differences are discussed here. With its long sequence lengths and CV capabilities, the sequencer can be used as a CV recorder by setting the FILL CV input to a constant voltage greater than 1V and activating the MEM button, thereby sampling the CV IN port at every clock edge and committing its voltage to memory.

This sequencer has no concept of tied notes; when pasting sequences using the Portable sequence format, notes that are longer than one step will have successive gate pulses on each step comprising the note.

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ChordKey

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A keyboard-based chord generator with room to store 25 chords, that can be recalled using a 0 to 2V control voltage. Up to four notes can be set for each chord using the keyboard and the octave buttons. The FourView module can also be used as an expander for the ChordKey to view the note names of the notes comprising the chord or the name of the chord itself; in this case no cables need to be connected to FourView it is immediately to the right of ChordKey.

An expander is also available (titled CHD-X), which offers four polyphonic quantizers that can be used to quantize any pitch CVs to the notes of the active chord selected in ChordKey. When the ChordKey expander is used independently, it will quantize pitch CVs according to all twelve notes.

Other options are also available in the right-click menu:

The Portable sequence standard can also be used to copy/paste chords externally, for use in sequencers or other modules (and also within ChordKey itself). For this, use the menu item labeled “Portable sequence” instead of the internal copy/paste actions. The “Copy chord” item will copy all notes to a sequence of one step thus preserving the chord, whereas “Copy chord as sequence” will arpeggiate the chord into a sequence of (up to) four steps, which can be useful for copying the notes into monophonic sequencers. The “Paste chord” item takes only the notes that share the same time step as that of the first note given (thus a true chord), whereas the “Paste sequence as chord” item makes a chord out of the first four notes given, irrespective of when they occur in the sequence, which can be useful for making a chord from the notes in a series of steps in a monophonic sequencer. Here are the keyboard shortcuts for these commands:

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Clocked/Clkd

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Clocked: A chainable master clock module with swing, clock delay and pulse width controls, with master BPM from 30 to 300 and all mult/div ratios up to 16, including 1.5 and 2.5, and with additional ratios spanning prime numbers and powers of two up to 64. The clock can produce waveforms with adjustable pulse widths for use with envelope generators or sequencers that use the clock pulse to produce their gate signals. The clock can also be synchronized to an external clock source.

Clkd: A smaller version of Clocked but without swing, clock delay and pulse width.

For a tutorial on Clocked regarding chaining, clock multiplications and divisions, swing and clock delay features, please see Nigel Sixsmith’s Talking Rackheads episode 12. It is also strongly recommended to read the section general concepts for more relevant information that is not repeated here.

In place of a detailed explanation of these three main controls (Swing, PW and Delay), it is recommended to connect the outputs to a scope or a logic analyzer, such as the VCV Scope (pictured above) or the SubmarineFree LA-108, to observe the effects of the different controls.

PW and Swing CV inputs are aso available in the Clocked expander module (available for Clocked only). These inputs have a range of -5V to 5V when the corresponding knobs are be in their default position. With the corresponding knobs turned full left, the usable range on the inputs becomes 0V to 10V, with no-swing and normal-pulse-width correspond to 5V on the CV inputs.

Many options are available in the modules’ right-click menu, and can be used to setup Clocked/Clkd for your particular needs. In particular, the RUN CV input is trigger sensitive by default, but can be made level sensitive (gate mode) by turning on the “Run CV input is level sensitive” option; when chaining multiple Clocked/Clkd modules, only the first module in the chain should have this option turned on.

Clocked and Clkd also feature the ability to automatically patch the Reset, Run and BPM cables to a designated clock master. Any instance of Clocked or Clkd can be designated as the clock master using the module’s “Auto-patch” menu entry. When auto-patching clocks: if the slave clock already has a connection to one of the inputs mentioned above, that input un-touched; the status of the “Outputs reset high when not running” setting will be copied from the master clock into the slave clock.

External synchronization

By default, the clock’s BPM input is level sensitive and follows Rack standards for BPM CVs. Synchronizing Clocked to an external clock signal can be done by selecting a mode other than “CV” with the MODE buttons located below the BPM input jack. The possible synchronization settings are: P2, P4, P8, P12, P16, P24, where the number indicates the number of pulses per step of the external clock source.

When using a chain of Clocked modules, all modules must have the same mode setting. The LED next to the mode buttons will light up when the sync mode is enabled; however, when no cable is connected to the BPM input jack, a regular clock is produced according to the BPM knob’s value.

When using external clock synchronization, Clocked syncs itself to the incoming clock pulse, and will stay synchronized, as opposed to just calculating the BPM from the external source. This means that it will not drift (or that it will drift in time with the incoming pulses if they drift), and it should stay perfectly synchronized over time; it also allows for latency compensation. Here are a few points to keep in mind when using clock synchronization.

  1. Clocked can not be manually turned on in clock sync mode, it will autostart on the first pulse it receives.
  2. Clocked will automatically stop when the pulses stop, but in order to detect this, it take a small amount of time. To stop the clock quickly, you can simply send a pulse to the RUN CV input, and if the clock is running, it will turn off.
  3. The external clock must be capable of sending clocks at a minimum of 2 pulses per quarter note (PPQN) and should not have any swing.
  4. Clocked does not perform any interval averaging and tries to sync to the incomming pulses as rapidly as possible. This may sometimes cause the BPM setting to fluctuate widely before reaching a perfect lock.
  5. Clocked can support and synchronize to fractional BPM values (ex.: 133.33 BPM), but will show the BPM rounded to the nearest integer in the BPM display.
  6. For low clock BPMs, synchronization may take some time if the external clock changes markedly from the last BPM it was synchronized to. Making gradual tempo changes is always recommended, and increasing the PPQN setting may also help. An other method consists in priming Clocked with is correct BPM first, to let it learn the new BPM, so that all further runs at that BPM will sync perfectly.
  7. When sending a clock from a DAW or other source external to Clocked in Rack, best results are obtained when sending this clock through an audio channel as opposed to midi clocks.

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CVPad

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A programmable CV controller with 16 pads, that can be configured into 1x16, 2x8 or 4x4 group(s). Many use cases are possible, one of which can be to manually select sequences to play in Foundry and many of the Phrase Sequencers, and more generally to control parameters for a live performance by providing quick access to different CV values.

The FourView module can also be used as an expander for the CVPad to view the note names of the selected pads; in this case no cables need to be connected to FourView provided it is placed immediately to the right of CVPad.

The module also features sliders and menu items to copy and paste the CVs, and also to offset/multiply/divide the stored CVs.

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Foundry

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A 4-track phrase sequencer with 32 steps per sequence, 64 sequences per track, 99 phrases per song. A phrase is a sequence number and a repetition count. Each track holds one song and can be independently clocked and edited. The SEL and ALL buttons allow the selection and simultaneous editing across multiple steps and tracks respectively.

CVs can be entered into the sequencer via CV inputs when using an external keyboard controller or via the built-in controls on the module itself. When notes are entered on the built-in keyboard using right-clicks of the mouse, the sequencer automatically moves to the next step. Holding ctrl while right-clicking also copies the current note/gate-type over when moving to the next step. Double-click defaults are supported on the three main knobs.

The following block diagram shows how the different sequencer elements are hierarchically related.

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Here are some further details on the different functions of the sequencer. It is also strongly recommended to read the section general concepts for more relevant information that is not repeated here. For an overview of the sequencer’s functionality, please see Omri Cohen’s Foundry tutorial (the tutorial was made with a previous version of Foundry wherein the main SEQ/SONG switch had an alternate behavior) and a quick followup video explaining more recent additions to the sequencer.

By default the sequencer always restarts the song (when in song mode); however, this may not always be wanted. To play the song just once, activate the option Single shot song in the right-click menu of the module. Since Foundry is a multitrack sequencer and there is only one global run state, one of the four tracks has to be used as the reference to stop the sequencer. This option is only well-defined when the song’s run mode is either FWD or REV.

For chords or polyphonic content, an option in the module’s right-click menu can be used to poly merge other tracks into track A outputs. For example, when the Poly merge into track A outputs is set to Tracks B and C, each of the CV, GATE, CV2 outputs of track A becomes polyphonic, with the content of track A in the channel 1, the content of track B in channel 2 and track C in channel 3. When a track is poly merged into track A, its output ports are set to a constant 0V. This is perfect for creating chords for polyphonic oscillators/ADSRs etc.

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GateSeq64

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A 64 step gate sequencer with the ability to define probabilities for each step. A configuration switch allows the sequencer to output quad 16 step sequences, dual 32 step sequences or single 64 step sequences. To see the sequencer in action and for a tutorial on how it works, please see this segment of Nigel Sixsmith’s Talking Rackheads episode 10; some of the functionality may have changed since the video was created, however. It is also strongly recommended to read the section general concepts for more relevant information that is not repeated here.

When running in the 4x16 configuration, each of the four rows is sent to the four GATE output jacks (jacks 1 to 4, with jack 1 being the top-most jack). In the 2x32 configuration, jacks 1 and 3 are used, and in the 1x64 configuration, only jack 1 is used (top-most jack). When activating a given step by clicking it once, it will turn green showing that the step is on. Clicking the “p” button turns it yellow, and the main display shows the probability associated with this step. While the probability remains shown, the probability can be adjusted with the main knob, in 0.02 increments, between 0 and 1. When a yellow step is selected, clicking the “p” button again will turn it off.

This sequencer also features the song mode found in PhraseSeq16; 64 phrases can be defined, where a phrase is an index into a set of 32 sequences. In GateSeq64, the song steps are shown using the entire grid of steps, overlapped with the actual sequence progression in lighter shades in the lights. The actual content of the sequences is shown in white in Song mode. Here are a few more points regarding Song mode:

  1. When not running, the phrase cursor position is shown with a red light.
  2. When running, the current phrase being played is shown with a full green light and the position in the sequence is shown with a pale green light.
  3. When running, clicking a phrase turns it red (the currently playing one in green is still visible), and the knob can be used to change the sequence mapped to that phrase for live song editing. After 4 seconds of inactivity, the editing disappears.

Copy-pasting ALL also copies the run mode and length of a given sequence, along with gate states and probabilities, whereas only gates and probabilities are copied when 4 or ROW are selected. More advanced copy-paste shortcuts are also available when clicking copy in Seq mode and then paste in Song mode (and vice versa); see cross paste below. The SEQ CV input, sequence length selection and run MODES are all identical to those found in PhraseSeq16.

Although no Write capabilities appear in the main part of the module, automatically storing patterns into the sequencer can be performed using the CV inputs in the GateSeq64 expander module (this is a separate module labeled "GS-X"). The cursor is stepped forward on each write, and can be repositioned at the first step by pressing the reset button, or at an arbitrary step by simply clicking that given step. When the cursor is not flashing, clicking any step will make it appear. The Write-gate (full circle) and Write-empty (empty circle) inputs (2nd and 3rd from the bottom) can be used to enter on-gates and off-gates in succession with separate external triggers (buttons). The bottom-most input is used to move the cursor to the left, whereas the Write input at the top can be used to move the cursor to the right when Gate In and Prob are unconnected. When either of these inputs is connected, the values are used to program the sequencer gates and probabilities. The extra CV inputs only have an effect in Seq mode.

As in the PhraseSeq sequencers, sequence numbers can also be typed in using the computer keyboard when the mouse cursor is placed over the SEQ# display; when in song mode, the space bar can be used to automatically move to the next phrase in the song. Two key presses within the span of one second will register as a two digit sequence number.

Advanced gate mode

The advanced gate mode in GateSeq64 has some similarities to the one available in the PhraseSeq16/32 sequencers, and is covered in Omri Cohen’s advanced gate mode tutorial. As of version 0.6.12, each gate type has its own LED button, instead of the two cursor type buttons that were used in the previous versions.

Holding the MODE button for two seconds allows the selection of the clock resolution, in number of pulses per step (PPS). When set to a value greater than 1, which unlocks the advanced gate mode, the sequencer will skip this many clock pulses before advancing to the next step. In such cases, a multiplied clock must be supplied in order to keep the same tempo in the sequencer. In advanced gate mode, the pulse width of the clock is not used and has no effect on the gates.

The PPS be a multiple of 4 for the first three gate types, while the PPS be a multiple of 6 for the last five gate types. A chosen gate type not meeting its required pulse rate will have a red LED beside it to indicate this (normally it is green). When a gate type is red, the sequencer will still emit a (possibly empty) gate pattern for that step, but with no guarantee that it will match the type that was selected. All gate types can be used when selecting a PPS value of 12 or 24.

Cross paste

Pressing the copy button in one mode (Seq or Song), and then the paste button in the opposite mode would normally result in an invalid operation. In these cases, depending on the state of the copy-paste switch (4/8/ALL), called type below, the following shortcuts are performed:

Cross paste from Song to Seq  
Type   Display   Result
4      RGT       Randomizes the gate states of the current sequence
8      RPR       Randomizes the probability states and values of the current sequence
ALL    CLR       Clears (initializes) the current sequence

Cross paste from Seq to Song
Type   Display   Result
4      INC       Sets the song phrases to the sequences 1, 2, ..., 64
8      RPH       Sets the song phrases to random sequences
ALL    CLR       Clears (initializes) the song (all 1s)

In cross paste operation, the copied content is actually irrelevant and unused.

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PhraseSeq16

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A 16 phrase sequencer module, where each phrase is an index into a set of 16 sequences of 16 steps (maximum). CVs can be entered via a CV input when using an external keyboard controller or via the built-in keyboard on the module itself. Using the song mode, a 256-step sequence can be created. With two separate gates per step, gate 2 is perfect for use as an accent if desired. When notes are entered on the built-in keyboard using right-clicks, the sequencer automatically moves to the next step. Holding ctrl while right-clicking also copies the current note/gate-type over when moving to the next step. Double-click defaults are supported on the main knob.

The following block diagram shows how sequences and phrases relate to each other to create a song. In the diagram, a 12-bar blues pattern is created by setting the song length to 12, the step lengths to 8 (not visible in the figure), and then creating 4 sequences. The 12 phrases are indexes into the 4 sequences that were created.

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Familiarity with the VCV SEQ-3 sequencer is recommended, as some operating principles are similar in both sequencers. It is also strongly recommended to read the section general concepts for more relevant information that is not repeated here. For an in depth review of the sequencer’s capabilities, please see Nigel Sixsmith’s Talking Rackheads episode 8 or Omri Cohen’s PhraseSeq tutorial.

Tied steps

When CVs are intended to be held across subsequent steps, this button can be used to tie the CV of the current step to the CV of the previous step. When tied, any changes to the CV of the head note will be propagated to all consecutive contiguous tied notes automatically. Two different gate 1 behaviors are available and can be toggled in the right-click menu. All gate types are adjusted automatically when tying and untying notes, and in all cases, manual inspection of the gate types will reveal what has been done in the sequencer. Any change to this option will only take effect on subsequent edits in the sequencer, such that currently entered tied notes are not automatically changed.

The following diagram shows the effect of the Held tied notes option.

Held tied notes activated
CV:    D# D# D# D# 
Gate:  -- -- -- -_
Step:  s1 s2 s3 s4

Held tied notes deactivated
CV:    D# D# D# D# 
Gate:  -_ __ __ __
Step:  s1 s2 s3 s4

Extra CV inputs are also available via the PhraseSeq expander module (this is a separate module labeled "PS-X"). Only the bottom-most input is level sensitive, the other four are trigger inputs. The expander CV inputs can only be used in Seq mode.

Advanced gate mode

For a video introduction to the advanced gate mode, please see Omri Cohen’s advanced gate mode tutorial. As of version 0.6.12, the keyboard mode (used to enter notes vs gate types) can be set explicitly using the two small LED buttons above the keyboard, instead of the temporary editing time that was activated when a gate was turned on (previous versions).

Holding the MODE button for two seconds allows the selection of the clock resolution, in number of pulses per step (PPS). When set to a value greater than 1, which unlocks the advanced gate mode, the sequencer will skip this many clock pulses before advancing to the next step. In such cases, a multiplied clock must be supplied in order to keep the same tempo in the sequencer. In advanced gate mode, the pulse width of the clock is not used and has no effect on the gates.

In the advanced gate mode, the Gate1 and Gate2 lights will be a different color, and the onboard keyboard can be used not only to enter note values, but also to select one of the 12 types of gates for a given step. To enter gates, make sure the LED button located above the E and F keys is activated (pressing this button multiple times alternates between gate 1 and gate 2); to enter notes again, press the LED button above the B key. Advanced gates can only be set while in Seq mode. Here are the different gate types and their minimum PPS requirements.

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All PPS settings will work for the full gate (the F key) as well as triggers (the B key). Triggers are 10ms in duration. A full gate remains high during the entire step, and if the next step’s gate is active, then the gate continues without interruption into that next step. When PPS requirements are not met, the sequencer will not allow invalid gate types to be entered on the keyboard. For example, if PPS is set to 6, then the 75% gate (the E key) can not be selected. Selecting a PPS value of 12 or 24 will ensure that all gate types can be used (i.e. that all PPS requirements are met irrespective of the gate type chosen).

Cross paste

Pressing the copy button in one mode (Seq or Song), and then the paste button in the opposite mode would normally result in an invalid operation. In these cases, depending on the state of the copy-paste switch (4/8/ALL), called type below, the following shortcuts are performed:

Cross paste from Song to Seq  
Type   Display   Result
4      RCV       Randomizes the CVs (pitches) of the current sequence
8      RG1       Randomizes all gates #1 of the current sequence
ALL    TG1       Toggles all gates #1 of the current sequence

Cross paste from Seq to Song
Type   Display   Result
4      INC       Sets the song phrases to the sequences 1, 2, ..., 16
8      RPH       Sets the song phrases to random sequences
ALL    CLR       Clears (initializes) the song (all 1s)

In cross paste operation, the copied content is actually irrelevant and unused.

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PhraseSeq32

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A 32 phrase sequencer module, where each phrase is an index into a set of 32 sequences of 32 steps (maximum). This sequencer is very similar to PhraseSeq16, but with an added configuration switch allowing the sequencer to output dual 16 step sequences (2x16) instead of single 32 step sequences (1x32). When the 1x32 configuration is selected, only the top channel outputs are used (labeled A), and when the 2x16 configuration is selected, the top row is sent to the top outputs (CV and gates A), whereas the bottom row of steps is sent to the bottom outputs (CV and gates B).

When running in the 2x16 configuration and in Seq mode, the following details become relevant:

  1. When ATTACH is activated, clicking any step in a given row will attach the edit head to that row.
  2. Only the row corresponding to the edit head’s position will be transposed or rotated when the TRAN/ROT button is used.
  3. One extra run mode is also available for sequences, called RN2. This run mode allows the two sequences to play randomly but separately, as opposed to RND which plays them randomly but together.

Other than these characteristics, the rest of PhraseSeq32’s functionality is identical to that of PhraseSeq16, including the use of the expander module.

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SMS16

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An all-in-one pre-patched semi-modular synthesizer. Based on the VCV Fundamental modules by VCV and the PhraseSeq16 sequencer (above). Please see those links for the respective manuals, while keeping in mind that not all features of the Fundamental modules were implemented in SMS16 (Semi-Modular Synth 16). A typical signal flow is internally patched by default, as shown by the interconnecting lines on the faceplate of the module. The majority of the internal connections can be overridden by any cables patched into those related jacks.

This module can be used for quickly exploring ideas for sequences, and is also useful for those new to modular synthesis before learning how to fill the screen with cables! Also note that the final output is the low-pass output of the VCF module (Voltage Controlled Filter). The VCF is purposely placed after the VCA (Voltage Controlled Amplifier) in the signal flow, such that the VCF can be lightly saturated, producing a thicker sound, especially when the Drive knob is turned up.

Extra controls were also added to the LFO (Low Frequency Oscillator), namely GAIN and OFFSET, to be able to easily modulate any other on-board parameter. With maximum gain, the LFO produces a 10V peak-to-peak signal (i.e. 5V amplitude). The offset knob is automatically scaled such that with maximum (minimum) offset, the signal’s maximum (minimum) voltage is +10V (-10V). That is, with the gain set to 0, the offset value spans -10V to +10V, and with the gain set to maximum, the offset value spans -5V to +5V. Also note that the clock LFO is automatically reset on every reset event in the sequencer.

The SMS16 also features the advanced gate mode of the PhraseSeq16. When changing the clock resolution in the SMS16, the onboard clock will automatically be scaled accordingly and no multiplied clock needs to be supplied to the module.

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Tact/Tact1/TactG

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Touch-like controller modules CV outputs and variable rate of change. With a fast rate of change, the controllers offer an alternative to knobs for setting parameters, and with a slow rate of change they can be used to automate in-out fades, for example, freeing the performer to work elsewhere in the patch. Tact-1 is a single channel version of Tact with fewer options, while Tact-G is a Tact-1 with one gate output and two offset controls.

A 0V CV is initially stored in the CV memory and the slide switches are in the off position, thereby allowing the Recall to act as a Reset by default. An option in the right-click menu, called Level sensitive arrow CV inputs can be activated to control the duration of the transition. When this option is turned on, the input must be continuously held above 1V for the transition to progress, and when the input goes back under 1V, the transition will stop at its current level.

The Auto-return option in the modules’ right menus can be used to momentarily affect the tact pads with the mouse, and have the level return to a prescribed value upon releasing the mouse button. When this option is activated, the Arrow inputs implicitly become level sensitive and can also be used to momentarily effect the level.

The x3 switch on Tact-G, or alternatively the x3 menu options in Tact and Tact-1, can be used to tripple the rate knob’s value for even slower transitions (rate knob is 0 to 12 s/V when active).

In Tact-G, two offset controls are added, one is a knob for direct control while the other is a CV input with attenuverter. Both options can be used simultaneously, for adding a random source in offset 2 for example, while still allowing a manual offset using the first offset. The gate outputs can be chained when using multiple Tact-G modules using the chain input.

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TwelveKey

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A chainable keyboard controller for your virtual Rack. When multiple TwelveKey modules are connected in series from left to right, only the octave of the left-most module needs to be set, all other down-chain modules’ octaves are set automatically. The aggregate output is that of the right-most module. To set up a chain of TwelveKey modules, simply connect the four outputs on the right side of a module to the four inputs of the next module beside it (typically to the right). With creative patching, the velocity output can be used to modulate a filter, to perform pitch bends, etc. The velocity is controlled by pressing the keys at different vertical positions within the guide marks on the keys. For a short introduction to the module, please see Omri Cohen’s TwelveKey video.

Options available in the right-click menu include:

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WriteSeq32/64

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WriteSeq32 is a three-channel 32-step writable sequencer module. Although the display shows note names (ex. C4#, D5, etc.), any voltage within the -10V to 10V range can be stored/played in the sequencer, whether it is used as a pitch CV or not, and whether it is quantized or not. Gate states and window selection can be done by pressing the 8 and 4 LED buttons respectively located below and above the main display. Familiarity with the VCV SEQ-3 sequencer is recommended, as some operating principles are similar in both sequencers. It is also strongly recommended to read the section general concepts for more relevant information that is not repeated here.

WriteSeq64 is a four-channel 64-step writable sequencer module. This sequencer is more versatile than WriteSeq32 since each channel has its own step position and maximum number of steps (length). Sequences of different lengths can be created, with different starting points. A fifth channel is available to be used as a staging area.

WriteSeq64 has dual clock inputs, where each controls a pair of channels. When no wire is connected to CLOCK 3,4, the CLOCK 1,2 signal is used internally as the clock for channels 3 and 4.

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Utilities

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Part

A gate splitter module based on a CV input and a split point. One use for this module is to split a polyphonic gate signal from a keyboard into two different polyphonic gate signals, such that the left and right hand parts can be sent to different voices. In such a case, the polyphonic CV should also be sent directly to each voice, and only the gates below/above the split point will produce sound in their respective voices. The module can also be used with monophonic signals. When chaining two Part modules to select a range of notes (with an upper and lower bound), it is important that the CV input of the second Part module be connected to the THRU output of the first Part module, to ensure gates and CVs have identical propagation delays. This is necessary to avoid glitches that can occur when gates are held continually high and the CV changes from a value above the upper bound to below the lower bound in two succesive Rack samples (or vice-versa).

FourView

A chord viewer module that shows the note names of up to 4 CVs, or the name of the chord represented by these CVs. Sharp or flat notation is selectable in the right-click menu. Bottom jacks are through outputs. FourView can also function as an expander for ChordKey or CVPad by placing it to the right of either of those two modules; in this case: a) no cables need to be connected in order to view the note names of the chord notes or pad voltages and b) the through outputs are not used. The FourView module also allows the copying of the displayed notes via the Portable sequence format for pasting as a chord in ChordKey or other modules. For more information, please see the ChordKey manual, as the two available copy options are the same as in that module.

Hotkey

Sends a trigger when a given keyboard key is pressed. The mouse cursor must be over the module. This module was made to synchronize audio recording using VCV Recorder with video recording (using OBS Studio for example). Set a hotkey in OBS to automatically have it start/stop recording upon a given keypress (works even when OBS is not in focus), then maximize Rack and set the same key in Hotkey; both recorders can then be started and stopped simultaneously on the same key-press. Send the trig output of Hotkey into the trig input of VCV Recorder.

The current hotkey is visible in the right-click menu of the module and is automatically saved.

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Hall of Fame

Here are a few videos featuring Impromptu Modular, which I find particularly very inspiring and interesting (listed in no particular order). Many talented Rackheads have made tracks using Impromptu modules, and this list could in fact be quite long. I have no formal criteria for why a track ends up in the list or doesn’t.

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