Signal Function Set Sequencer System

The Sequencer System is a set of rhythm and song-form modules for VCV Rack. Arrange holds the song’s sections. Meter is a time-signature-aware master clock with per-subdivision swing, and its expander Meter X covers long-form structure. Beat is a single-voice drum sequencer. Note is a pitched sequencer built on the same design as Beat, with 19 scales including just-intonation harmonics and Indonesian Gamelan tunings.

This page shows how the modules fit together, and each one also has its own page with the full detail: Arrange, Meter, Meter X, Beat, Note.

Each module works on its own, but they are designed to work together. One Meter drives a rig of Beats and Notes, which all share its bar boundaries, swing and reset behaviour. Each Beat or Note is a single voice, so to build a kit you add as many as you need, and each one holds its own pattern bank and pattern lengths.

Meter: the master clock

Full detail: the Meter page.

Many VCV clocks are subdivision dividers that emit evenly spaced pulses at fixed ratios. Meter also tracks the musical structure of those pulses, counting bars and beats in a time signature you can change with CV, and it applies swing to each subdivision. It is 18 HP wide.

Six musical subdivisions

Each output runs at the rate implied by the current time signature:

• BAR: one pulse at the start of every bar
• QUARTER: quarter notes
• EIGHTH: eighth notes
• SIXTEENTH: sixteenth notes
• QUARTER TRIPLET: three pulses per quarter
• EIGHTH TRIPLET: three pulses per eighth

Time signature with CV

Both the numerator (1-16) and denominator (1, 2, 4, 8, 16, 32) are knobs with CV inputs. Time signature changes are queued for the next bar boundary by default, so the current bar plays to completion. A context menu option applies changes immediately instead, which can cut a bar short or leave it with an irregular final beat.

Swing per output

Each subdivision (except BAR) has its own swing trimpot (-50% to +50%) and matching CV input. Positive swing delays the off-beats for a shuffle feel; negative swing fires them early for a rushed feel.

For each swingable subdivision, Meter provides two output jacks: SWG (swung) and GRD (grid). You can patch the swung eighth into the hat and the grid eighth into a synth bass, so straight and swung parts run from the same Meter. Swing values are latched once per bar, so turning a swing control cannot move a pulse partway through a beat.

External clock sync

Patch a clock pulse train into EXT CLOCK and Meter measures the inter-pulse interval to derive BPM. PPQN is selectable (1, 2, 4, 8, 12, 16, 24). When external clock is patched, the BPM knob is overridden and a sync indicator flashes on each external pulse.

Display

The top status line shows BPM, the time signature (with a 7/8 style pending-change indicator) and a bar counter. Below it, six rows show each output’s pulses across the bar, with a bright tick at each position where the output fires and a faint tick at each un-swung position, joined by a line to the swung position. The tick that just fired flashes and decays over ~100ms. A position tracker at the bottom shows the current sixteenth-note position in the bar.

Meter X: long-form structure

Full detail: the Meter X page.

Meter’s own panel covers the musical subdivisions (bar, quarter, eighth, sixteenth and triplets), each with swing. Meter X adds outputs for structure that unfolds over minutes rather than beats.

Place it immediately to the right of Meter and it reads Meter’s clock over the expander bus, with no cables needed. It is 8 HP wide.

Outputs

• 24 PPQN: 24 pulses per quarter note, the MIDI-standard clock resolution. It is un-swung, so it stays an even timing reference whatever Meter’s swing settings are, and anything applying its own shuffle downstream is not swinging an already-swung clock.
• RUN: 10V while Meter is running.
• BAR, 2, 4, 8, 16, 32, 64, 128: a trigger every N bars, on the downbeat.

All the bar triggers are aligned to reset: they fire on bars 1, 1+N, 1+2N, and so on. At reset every row fires together, and from then on every bar output stays aligned with the song’s bar count.

The pies

Each bar row has a small pie chart that fills clockwise as you advance through that output’s cycle, then resets when it fires. The 4-bar pie fills over four bars, and the 128-bar pie fills over 128. Instead of counting bars in your head, you can see that you are three-quarters of the way through a 32-bar section. The pies freeze while Meter is stopped. (The 24 PPQN and RUN rows have no cycle, so they get no pie.)

Why 24 PPQN

Use 24 PPQN to drive anything that expects a fine clock resolution rather than a musical subdivision, such as modules that derive their own subdivisions internally, modules that apply their own swing, MIDI interfaces and clock converters. Meter’s own PPQN setting applies to the clock it receives, while Meter X’s 24 PPQN is a clock it sends.

Beat: drum voice sequencer

Full detail: the Beat page.

Beat is a single-voice pattern sequencer that runs from Meter or any other source of clock and bar pulses. Each Beat instance sequences one drum voice, with eight patterns of sixteen steps and per-step velocity, accent and probability. It is 10 HP wide.

Patterns and steps

Each Beat instance holds 8 patterns of 16 steps. Each step has four properties: on/off, velocity, accent, and probability. Each pattern has its own length (1-16) and repeat count (1-8 bars). Patterns can be marked active or inactive: inactive patterns are skipped in the rotation, so you can chain a subset without manually editing each one.

When the playhead reaches the last active step, the next CLOCK pulse wraps it back to step 0, even in the middle of a bar. A 5-step pattern clocked at 16th notes therefore keeps cycling against the bar, which produces a cross-rhythm without any extra patching.

Display modes

You edit patterns on the display, which has four mode tabs: STEPS, VEL, ACC and PROB.

• STEPS: click cells to toggle on/off, drag to paint
• VEL: click-and-drag vertically to set per-step velocity (0-10V S&H output)
• ACC: click to toggle accent flag (1ms pulse on the ACC output)
• PROB: click-and-drag vertically to set per-step probability (0-100% chance of firing)

Below the grid are length dots, a pattern selector with repeat-count indicators, and a repeats bar, which respond to clicks, drags, the scroll wheel and double-clicks. The Beat page lists what each one does.

Inputs and outputs

Note: pitched sequencer

Full detail: the Note page.

Note is a pitched (CV/gate) sequencer that shares Beat’s clock, bar and repeat behaviour, its eight patterns, its per-step velocity, accent and probability, and its four edit modes. Each step also carries a pitch quantized to a selectable scale and root. Note is 10 HP wide and has 8 steps per pattern.

Pitch matrix

The display matrix is 8 columns (steps) by 13 rows (pitches). The bottom row is the scale’s root pitch; rows above are successive scale degrees, with the root plus one octave always shown at the top so the scale octave is visible regardless of scale size. Out-of-scale rows are dim and not clickable.

Click a cell in STEPS mode to set that step’s pitch; click again to clear (rest). Drag-paint paints the same row across columns.

19 scales, including non-12-TET

The scales are Chromatic, Major, Minor, Dorian, Phrygian, Lydian, Mixolydian, Locrian, Harmonic Minor, Melodic Minor, the major and minor pentatonics, Blues, Whole-tone, Hijaz and Hirajoshi, plus three scales whose pitches lie between the twelve equal-tempered steps, so a chromatic quantizer cannot produce them:

• Harmonic: just-intonation harmonics 1 through 12. The V/OCT output gives precise just-intonation ratios.
• Pelog: 7-tone Indonesian Gamelan scale, an approximation of Surakarta tuning
• Slendro: 5-tone Indonesian Gamelan scale, tuned as five equal divisions of the octave

Played alongside equal-tempered instruments, these three scales produce audible differences in pitch from the equal-tempered notes.

Root, scale, octave: chainable

ROOT, SCALE, and OCT each have a knob, a CV input, and an OUT jack that relays the current value. Patch one Note’s ROOT OUT into another Note’s ROOT CV, and changing the key of the first (say, a bass line) transposes the second (say, an arpeggio) with it. The ROOT and SCALE CVs use the same convention as Fugue and Muse, so a single root and scale source can set the key for every SFS module in a rig.

Inputs and outputs

Arrange: song form

Full detail: the Arrange page.

Meter keeps time, and Beat and Note play parts. Arrange sits above them and sets which section of the song is playing, how many bars it lasts, its key and tempo, and which instruments play during it.

Arrange is a single horizontal chain of 8 phrases. A phrase is a section of the song, such as an intro, verse, chorus or break, lasting a set number of bars. The arrangement steps through the active phrases in order and wraps back to the first.

Arrange does not generate a clock, and Meter remains the master. Arrange counts Meter’s bars and sends gated, divided clocks to your instruments. It is 34 HP wide.

Wiring it up

Patch Meter’s BAR into Arrange’s BAR input (this is what advances the arrangement) and whichever Meter subdivision you want as the base rate into CLOCK.

Then close the loop the other way: BPM out into Meter’s BPM CV, with Meter’s “BPM CV absolute” context-menu option enabled. That switches Meter’s BPM CV from an offset to an absolute 0.01V/BPM reading, so each phrase’s BPM trimpot sets the actual tempo of the song.

Per phrase

Each column carries a bar length (1-16, set on a 4x4 grid), an enable (double-click; inactive phrases are skipped), its own scale, root, and BPM, four channel enables, and a GATE output that stays high for the whole time that phrase is playing.

Linking key and tempo

Most songs keep the same key and tempo for many phrases, so Arrange links them by default. Small LED dots between the trimpot columns pass values down the chain, one dot per row, so scale, root and BPM link independently.

A linked phrase takes its value exactly from the leftmost phrase of its group. Its own trimpot is ignored, and the value is drawn dim on screen so you can see which phrases are following. Break a link and that phrase becomes independent, starting a new group that the phrases after it follow. One key and tempo for the whole song is therefore the default, and a key change takes a single click on a dot.

The four channels

The four channels are per-instrument clock buses. Each one feeds one instrument (a Beat, a Note, a Chance), and each phrase sets which of them are playing.

Per channel there’s a clock division trimpot (1 through 16, bar-aligned) and four outputs: CLOCK (the divided clock), BAR, RESET, and EOC.

CLOCK and BAR are muted on any phrase where that channel is disabled. Toggle a channel’s coloured bar off for the verse and that instrument stops, because it receives no clock, so nothing needs muting further down the patch. Toggle it back on for the chorus and its RESET fires, so the instrument re-enters at the start of its pattern rather than partway through. Division counters keep running while a channel is off, so a returning instrument stays phase-locked to the master.

Master outputs

The master outputs are BPM (0.01V per BPM, into Meter), ROOT (1V/oct, semitone-quantized), SCALE (1V per scale) and PHRASE (1V per phrase).

ROOT and SCALE use the same convention as Note, Fugue, Muse and Chance, so one arrangement sets the key of the whole patch. Arrange has no master Bar or Clock output, because Meter already provides both, and instruments should take their channel’s gated, divided versions so they drop in and out with the arrangement.

Patch ideas

A whole song, arranged: Meter BAR into Arrange BAR, Meter SIXTEENTH into Arrange CLOCK, Arrange BPM into Meter BPM CV (with “BPM CV absolute” on). Send channel 1 to a Beat (drums), channel 2 to a Note (bass, div 2) and channel 3 to a Chance (lead). Make P1 a 4-bar intro with only channel 1 on, P2-P3 an 8-bar verse with channels 1 and 2, and P4 a 16-bar chorus with all three. The instruments then come in and drop out with each section without any further patching.

Key change at the bridge: break the root link on P5 and set its ROOT trimpot up a fourth. P5 onward inherits the new key until the next break. Every Note and Chance following Arrange’s ROOT out transposes with it.

Long-form structure: Patch Meter X’s 32-bar output into a sequencer’s reset and its 8-bar output into a pattern advance. The sequencer then changes pattern every 8 bars and restarts every 32, and the pies show how far away each change is.

3-piece drum kit driven by Meter: Use three Beats for kick, snare and hat. Patch Meter QUARTER into the kick clock, swung Meter EIGHTH into the snare clock and swung Meter SIXTEENTH into the hat clock, and feed all three BAR inputs from Meter BAR and all three RESET inputs from Meter RESET. Each Beat holds its own pattern bank for its drum, and you set the swing for each voice on Meter.

Cross-rhythm playground: Patch Meter QUARTER TRIPLET into one Beat and Meter EIGHTH into another. The triplets fire three times for every two eighth notes, which gives a 3-against-2 polyrhythm.

Bass and arp from one Meter: Run two Notes from one Meter’s clock and bar pulses. Set Note 1 (bass) to a pentatonic scale, a low octave and a 4-step pattern, and Note 2 (arp) to the same scale, one octave up, with an 8-step pattern and every step on. Patch Note 1’s ROOT and SCALE OUT into Note 2’s ROOT and SCALE CV, so changing the bass key transposes the arp with it.

Gamelan ensemble: Set four Notes to the Slendro scale, chain their ROOT and SCALE OUT jacks so they share a root, and put each one in a different octave. Give them different pattern lengths (5, 6, 7 and 8 steps) so their patterns line up differently on each pass. Patch each one into a Tine for a metallic, inharmonic resonator voice.

Just-intonation drone: Set a Note to the Harmonic scale with a single sustained note on row 0 (the root) at maximum velocity. The V/OCT output gives just-intonation harmonics 1 through 12, so moving the note up the rows steps through the harmonic series.

Sequenced time signatures: Patch a slow LFO or sequencer into Meter’s NUM CV and DEN CV to morph the time signature mid-piece. Pending changes apply at the next bar boundary by default, so each bar plays complete in its old time signature before the new one starts.

External tempo follow: Patch a hardware MIDI clock or a Clk module into Meter’s EXT CLOCK at 24 PPQN. Meter follows the external tempo while still emitting its own subdivisions, swing, and bar boundaries.