Serum 2 Arpeggiator: The Complete Guide to Patterns, Expression & Glide

Note: This article is adapted from John’s EDMProd video tutorial, embedded above.

Serum 2’s arpeggiator can turn a held chord into a melody. But the really interesting part starts when you draw your own patterns, give individual notes different filter movements, and bend their pitches as the sequence plays.

You can build an acid-style line with accents, create a pattern that climbs through several octaves, or switch between variations while keeping everything on the beat. And you can do it inside the synth, with the same modulation system you use to design the sound itself.

This guide takes you through the complete tutorial, from your first three-note arp to expressive patterns and performance controls. The screenshots focus on Serum’s interface, and the audio examples let you hear the relevant musical passages without hunting through the video.

If you want to master Serum 2 inside and out, including its arpeggiator and clip sequencer, check out our course, Master Serum 2.

1. Turn a chord into an arp

An arpeggio is a chord whose notes play one after another. An arpeggiator takes the notes you hold and generates that sequence for you.

For a simple example, hold C, E♭, and G: the notes of C minor. With an ascending arp, Serum plays C → E♭ → G, then returns to C and repeats. The chord supplies the notes; the arpeggiator supplies their order and timing.

This is useful even if you already write melodies comfortably. A held chord can become a rolling bass, a pulsing chord part, or a high melodic figure, and changing the chord changes the notes available to the pattern.

Enable the ARP module

1. Load Serum 2 on an instrument track and choose a sound that responds clearly to separate notes.
2. Open the ARP module at the bottom of Serum.
3. Click the small power button beside the ARP label to enable it.
4. Choose Up in the Pattern section and play a chord on your MIDI keyboard. A held MIDI chord in your DAW works too.

Audio example · 4 seconds

A held chord becomes an arpeggio

If you hear an indistinct wash, try a pluck with a short release. A long pad envelope can keep earlier notes ringing while later notes arrive, making the sequence harder to follow. John makes exactly this kind of envelope adjustment when demonstrating repeated chords later in the tutorial.

Arpeggiator or clip sequencer?

Both can create repeating musical phrases, but the editing approach differs. In the arp’s custom pattern editor, the numbered rows select notes from your input chord. The Serum 2 clip sequencer gives you a piano roll for writing a sequence directly.

Reach for the arp when you want a reusable rhythmic shape that responds to the notes you hold. Use the clip sequencer when you want to work directly with a written phrase. This article focuses on the ARP module, which is a Serum 2 feature; the original Serum interface does not have this module.

2. Choose a shape and set the rate

The Shape selector in the Pattern section determines how Serum works through your held notes. You can start with a preset shape or choose Pattern to open the custom editor.

John adds a higher C to his C minor chord when demonstrating Up/Down. The extra octave makes the rising and falling contour easier to pick out.

Audio example · 6 seconds

An ascending and descending shape

Played is especially useful with a keyboard. Press the top note first, then the bottom note, then the middle note, and the order you entered becomes part of the result. You are choosing a sequence through your performance rather than always sorting the notes from low to high.

For Chord, shorten the amplitude envelope enough to reveal the retriggers. If the sound sustains at a constant level, repeatedly triggering the same chord may be much less obvious than you expect.

BPM sync versus Hz

The Rate control sets how quickly the arp runs. In BPM mode, its timing is tied to the project tempo. In Hz mode, you can set a free rate independent of that tempo relationship.

In John’s example, the project is at 140 BPM and the pattern is slowed to half speed, equivalent to a 70 BPM pattern tempo. That does not mean you have changed the DAW’s tempo. You have changed how fast this arp moves relative to it.

Keep the arp synchronized while building a part for a track. A slower rate is also useful while editing pitch bends: you can hear the movement inside each note instead of having it flash past. Notice that grid size and playback rate are separate controls. A finer editing grid lets you place events more precisely; it does not automatically speed up the pattern.

3. Draw custom patterns and understand note numbers

Choose Pattern in the Shape selector to work in the custom editor. This is where Serum’s arp becomes much more flexible than a basic Up/Down selector.

The graph resembles a piano roll, but its vertical rows are note indices, starting at zero. They select positions within the notes supplied to the arp. They are not fixed piano keys.

Imagine holding C, E♭, and G in ascending order:

Draw events on rows 0 → 1 → 2 → 1, and the resulting line is C → E♭ → G → E♭. Play a different chord and those same row choices select notes from the new input.

This explains an initially confusing moment in the video. John holds just one C, so several different rows all resolve to that same C. When he adds more notes, the pattern gains more distinct pitches without changing the drawn events.

What happens when you run out of held notes?

Under the normal wrapping setup John begins with, the pattern returns to the start of the available note set. If you hold three notes and use six consecutive rows, the second group of three can repeat the first group in the same register.

Later, you can use the Wrap Pitch and Range settings to move those repeated notes into higher octaves. We will separate that behavior from whole-pattern transposition below, because the two controls solve different problems.

You may also see D♯ on screen where this article says E♭. They name the same pitch in this context; E♭ is the appropriate spelling for the third of a C minor chord. Serum’s displayed sharp spelling does not mean the chord has changed.

4. Edit rhythm, note length, and stacked notes

Once the row numbers make sense, think of the custom editor as two decisions at once: when an event happens, and which input note it selects.

Double-click in an empty part of the graph to add a note event. Move it horizontally to change its timing or vertically to change its note index. Drag its edge to change its length. John also removes unwanted events by selecting and deleting them, or by double-clicking them.

Change the editing grid

The grid value sits near the top-left of the graph. A finer grid gives you smaller timing increments for placing and resizing notes. In the video, John settles on 1/32 to shorten notes and add quicker events.

Pause animationPlay animation · 8.0-second loop

Start with a straightforward grid and a short phrase. Once that works, add a smaller subdivision to one part of the pattern. One fast pickup can do more for the groove than filling every available space.

Pattern length and loop boundaries

The Length field controls the pattern’s overall length. John changes a one-bar pattern to four bars, then adjusts the view at the top to see more of the timeline.

Do not confuse a longer timeline with more musical content. If you extend the pattern but leave the new area empty, you have made more room to compose, not automatically filled that room with notes.

The start and end handles also let you focus playback on a shorter section. Later in the tutorial, John makes a loop six sixteenth notes long. That short phrase cycles at a different interval from a conventional one-bar loop, creating an evolving relationship with the beat.

Stack notes for chords inside the pattern

Place events on different rows at the same horizontal position to trigger multiple notes together. You can mix single-note motion with occasional stacks instead of choosing between a completely monophonic line and repeated full chords.

Audio example · 9 seconds

A more complex custom pattern

Keep enough polyphony in your patch if you want those stacks to sound as chords. A monophonic sound changes how simultaneous and overlapping notes behave, which can be useful for a bass line but works against a full chord demonstration.

5. Add accents that actually change the sound

The Accent lane underneath the note graph lets you emphasize selected events. The essential detail is that an accent affects velocity. It does not automatically make every preset louder or brighter.

John demonstrates this by adding accents and hearing no obvious change. The velocity source is moving, but it has not been assigned to an audible destination in his patch.

Route velocity to level

To make the accents affect volume, route VELO to an oscillator’s level. Set the base level and modulation depth so that lower-velocity notes have room to sound quieter and higher-velocity notes can stand out.

A useful check is to exaggerate the modulation temporarily. If accented and unaccented notes are still indistinguishable, check the routing and base value before drawing more accents.

Route velocity to filter cutoff

A more characterful option is to route velocity to the filter cutoff. Accented notes can then open the filter farther, changing brightness as well as emphasis. With a resonant filter and a suitable synth patch, this moves toward the acid-style effect John demonstrates.

Audio example · 6 seconds

Accents opening the filter

You can use both destinations. Level gives an accent more weight; cutoff gives it a different tone. They need not move by the same amount, and neither has to be pushed to its maximum.

6. Use per-step expression and pitch bends

Accents are only the start. The automation lanes below the arp graph can hold additional per-step information, including velocity variation, octave randomness, probability, and expression controls.

John uses Expression X to give individual events different modulation values. This is separate from choosing their note indices: a step can keep the same note while changing the filter or envelope behavior.

Add an Expression X lane

1. Add an expression lane from the lane selector below the graph.
2. Choose Expression X.
3. Give some steps higher values and others lower values.
4. Assign MPE Expression X as a modulation source for the parameter you want to control.
5. Set the modulation amount, then play the pattern and refine the values.

In the tutorial, John assigns Expression X to filter cutoff, which already has velocity modulation. Both sources now contribute to the cutoff’s movement. You can use velocity for a strong accent pattern and Expression X for another layer of tonal variation.

Audio example · 4 seconds

Expression adds another layer of filter movement

Next, John maps the same Expression X source to the amplitude envelope’s Decay time. A single event can now have a different brightness and a different decay from its neighbors.

That is a useful way to give a repeated sequence a sense of phrasing. One note can be short and dark, the next more open and sustained, without changing the underlying chord.

These values are programmed inside the arp. The source’s MPE Expression name does not mean you need to perform this lane on a specialist MPE keyboard. The pattern itself supplies the expression values demonstrated here.

Draw pitch movement within individual notes

The pitch-edit button at the far right of the editor exposes pitch lines on the events. Add a point and drag it to shape a bend. John slows the pattern so the movement is easier to hear, then adds several different curves.

Pause animationPlay animation · 8.0-second loop

Audio example · 11 seconds

The pattern with per-note pitch bends

Keep a distinction between choosing a different row and drawing a pitch curve. A row chooses a note from the input set. A pitch curve bends the selected event over time. That bend can travel away from the chord tones, so judge it as part of the melody rather than assuming every moment stays within the held chord.

Start with one bend at the end of a phrase. If the transition works, add another in a different position. The unbent notes give your ear a reference, which makes a deliberate bend more effective.

John later adds delay and reverb for space. Those effects can carry the movement beyond the dry note, but they are finishing choices; get the curve sounding right before extending its tail.

7. Create strums and save useful patterns

The Strum lane spreads the attacks of notes that would otherwise happen together. The important setup is a stack of simultaneous note events: there must be multiple notes at that position to strum.

If your pattern contains only isolated single notes, adding strum will not produce the chord sweep John demonstrates. Build the stack first, then use the Strum lane beneath it. Slow the rate if the staggered attacks are difficult to hear.

You can load factory patterns through the pattern name menu at the upper-left of the editor. John uses one of the basic strum patterns as an example, then returns to his custom pattern.

Save the pattern and the sound

Open that same pattern name menu and choose Save Pattern… to store an arp pattern you want to reuse. A descriptive name such as “Minor six-step glide” will be easier to find than a collection of numbered experiments.

Also save the Serum preset when you want to preserve the complete sound you are building. The audible result depends on more than the note graph: velocity and expression need their modulation assignments, and the oscillator, filter, envelopes, and effects all contribute to the patch.

8. Playback modes and New Only explained

There are two similarly named controls in the pattern editor that are easy to mix up:

• Mode controls how the playhead travels through the pattern.
• Step Mode controls what happens when a step triggers.

They also differ from the Shape selector discussed earlier, which chooses a built-in note order or the custom Pattern editor.

Choose a playback direction

Normal plays the pattern forward. Reverse plays it backward. Pendulum travels forward and backward, making a repeated phrase turn around rather than jump straight back to its beginning.

There are also random playback options, random start/end options, One Shot, and Static. John briefly runs through these in the video. They are worth trying on a pattern whose normal behavior you already know: the same notes can feel quite different when you change how the playhead encounters them.

For a predictable starting point, leave Mode on Normal. Then try Pendulum as a single variation. Changing the direction, rate, loop boundaries, and note order simultaneously makes it harder to identify which change you actually like.

Step Mode: Normal, Chord, and the “new” options

Normal follows the individual pattern events. Chord triggers the held chord on each step; the step numbers also influence its voicing.

John is candid in the tutorial that New Only does not behave as he expects when he holds notes. The manual supplies the key qualification: the “new” modes depend on a newly received input note coinciding with the step trigger. A chord you simply keep holding does not provide a new note-on at every step. Chord (new) applies that timing condition to chord triggering. Xfer’s Serum 2 User Guide, page 251.

That makes these more specialized than the normal repeating arp behavior. If your goal is “hold a chord and let it run,” start with Normal or Chord. If you want to investigate the new modes, use deliberately timed MIDI input and compare against Normal. That is a practical test setup, not a promise that the new mode will automatically quantize whatever you play.

9. Wrap notes into higher octaves

Wrap determines what happens when a pattern asks for a note index outside the notes you are holding. This is the setting behind the repeated-note behavior we saw earlier.

John’s demonstration uses six rows, 0 through 5, while holding only three keys. With normal wrapping and Range 0, the available three-note set repeats in the same octave.

He then increases the Wrap range and uses Pitch 12 to put the second group an octave higher.

Here is the result for the six-row example:

The octave labels here follow Serum’s display in the tutorial. A DAW may label the same MIDI pitches with different octave numbers, so follow the pitch relationship rather than worrying about that label difference.

Changing Pitch to 24 semitones makes the wrapped group two octaves higher in this example. The controls have distinct jobs: Pitch is the interval, while Range controls the extent of the wrapping transposition. John’s spoken explanation briefly calls the 24-semitone setting “range”; the on-screen Pitch field is the interval control.

Use wrapping when you want a custom graph to reach beyond the register of the keys you physically hold. You can keep a compact hand position and let the pattern provide a wider line.

10. Transpose the whole pattern

The lower Transpose section works on repetitions of the pattern. Instead of deciding how an out-of-range row resolves inside one pass, it shifts the pitch of later passes.

In the ascending example John demonstrates:

• Shift 12, Range 1: play the original pattern, then a pass one octave higher.
• Shift 12, Range 2: add another pass two octaves above the original.
• A different Shift interval changes the distance between passes. A negative interval moves downward.

Audio example · 6 seconds

One octave of whole-pattern transposition

Make the loop length part of the composition

John shortens the active region with the loop end handle. Instead of waiting through the full original bar, he first uses a shorter group, then chooses a loop containing six sixteenth notes.

Audio example · 5 seconds

A six-step loop against the beat

Six sixteenth notes do not fill a standard 4/4 bar. As the phrase repeats, its starting point moves through different positions relative to the bar. Combine that with transposition and the rhythm and register can both develop across successive passes.

Audio example · 6 seconds

The transposition range increases

This is a strong technique for a background sequence that stays interesting over a sustained harmony. If you want an obvious one-bar hook instead, start with a loop that fits the bar cleanly and introduce more unusual lengths only where the arrangement benefits.

Wrap versus Transpose at a glance

11. Copy variations, quantize launches, and latch notes

The row of slots at the bottom lets you keep several arp variations ready. John duplicates the current pattern by holding Option on his Mac and dragging it into the next slot.

Pause animationPlay animation · 8.0-second loop

Once copied, he changes the start position and length of the second pattern. You could also alter the rhythm, expression values, or transposition to create a response to the original phrase.

A small change is often enough. If the first pattern is your main motif, a shorter second pattern can act as a fill without sounding like an entirely unrelated part.

Quantize the switch between slots

Launch Quant in the Global section controls when a selected variation starts. John sets it to a bar so the next slot waits for an appropriate bar boundary rather than interrupting immediately.

This is useful when performing or auditioning variations over a running project. You can request the next pattern before the boundary and have the change land in time.

John enables Edit All when he wants to make the launch-setting change across his patterns. Turn it off again when you return to editing a variation independently, so you do not accidentally apply an intended local change more widely.

Use Latch to free your hands

Enable Latch, play the notes you want, and release your keys. Serum keeps the input notes latched so the arp can continue while you edit or perform other controls.

Disable Latch to release those held notes. If the arp keeps running after you lift your hands, checking Latch is a sensible first step before assuming something has gone wrong with MIDI.

12. Offset, repeats, gate, and chance

The Playback section gives you several ways to reshape the result without redrawing the graph.

Offset and Repeats

Offset moves the position used in the note order. It is a quick way to hear an existing pattern from a different starting point without moving each drawn event individually.

Repeats is set to infinite in much of the tutorial. With a finite setting, the arp stops after its allowed repetitions even if you keep holding the keys. John demonstrates that behavior by reducing the repeat count.

Use finite repeats for a short gesture or a fill. If you expect a sustained part and it unexpectedly stops, restore the repeat setting before looking elsewhere.

Gate changes note duration

At 100% Gate, the events use their normal full length. Lower Gate values release them earlier. Higher values extend them; at 200%, John demonstrates notes lasting twice as long, producing overlap.

The final audible length also depends on the synth envelope. A short gate with a long release can still leave a long tail. Conversely, a pluck that decays quickly can sound short even if the MIDI note remains active.

Combine overlap with portamento

John’s preferred variation is to raise Gate enough for overlap, then add Porta. This creates connected pitch movement between notes instead of isolated attacks.

Audio example · 9 seconds

Overlapping notes with portamento

This is a different approach from drawing per-note pitch curves. The curves let you specify a bend within a particular event; portamento controls transitions between notes according to the patch’s voice and glide settings. You can use both, but start with one so you can hear its contribution clearly.

Add probability with Chance

Chance controls the global likelihood of note events triggering. At 50%, each event has a 50% chance of occurring; it does not guarantee that exactly half of the notes will play in each loop.

Audio example · 5 seconds

A pattern with probabilistic gaps

There are also per-step probability controls in the editor. Use a per-step approach when you want particular ornamental events to be less reliable. Use the global control when you want to loosen the whole pattern.

For a main hook, keep enough dependable notes for the listener to recognize the phrase. Probability is especially effective on extra pickups, upper notes, and background motion. It is less useful if it keeps removing the one note that makes the melody work.

13. Build an expressive arp from scratch

Here is a practical exercise that brings the tutorial’s main techniques together. It is a suggested starting patch, rather than an exact numerical recreation of every setting John changes in the video.

Pass 1: Get a clear rhythm

Use a simple pluck, enable ARP, and hold C–E♭–G. Select Pattern and write a short sequence using rows 0, 1, and 2. Leave a few gaps instead of filling every grid division.

Keep normal playback, normal wrapping, and no whole-pattern pitch shift while you establish the phrase. Set a tempo-synced rate and listen against a basic beat in your project.

Pass 2: Give the notes different emphasis

Accent two events that help define the rhythm. Route velocity to filter cutoff, then set the modulation depth so the accents brighten those notes without making every event harsh.

If you also want a volume difference, add a smaller velocity-to-level assignment. Keep the main rhythm audible when you lower the listening volume; that is a useful sign that the emphasis is doing musical work.

Pass 3: Add expression to one phrase ending

Create an Expression X lane. Give the last event a different value and route the lane to envelope decay. Adjust the depth until the ending note has a distinct length.

Next, add one pitch curve to that event. Slow the rate temporarily while editing, then return to the intended speed. Decide whether the bend still reads as an intentional ending or has become too quick to matter.

Pass 4: Develop the register

Try one-octave wrapping if you want some higher notes inside the phrase. Alternatively, keep the notes compact and set the Transpose section to move the next pass up an octave.

Compare those choices before combining them. One changes the contour within the loop; the other creates a larger-scale rise across loops.

Pass 5: Create a variation and add space

Copy the pattern into another slot. Make the second version shorter, remove an event, or change one expression value. Set launch quantization so switching patterns fits the arrangement.

Finally, add a little delay or reverb, as John does in the tutorial. Recheck the note separation afterward: a spacious sound is useful only if the rhythm you worked on still comes through. Save both the useful arp pattern and the complete Serum preset.

14. Troubleshooting and further resources

For more detail, use Xfer’s official Serum 2 manual, particularly the “Using the Arpeggiator” chapter. It is the reference for the more specialized modes that John only touches on in this video.

You can also continue with these EDMProd guides:

• Serum 2 Clip Sequencer: The Complete Guide — write and manipulate phrases in Serum’s piano roll.
• Our Serum 2 guide — explore the synth around the arp: oscillators, effects, and modulation.
• Arpeggiator tricks and techniques — apply arpeggiated ideas more broadly in your music.
• Free Serum 2 preset packs — find more sounds to experiment with.

The next useful step is to build one short pattern and give it a clear role in a track. Once the rhythm works, choose an accent, a bend, or a variation that makes that role stronger. You do not need every arp feature in the same patch to create something worth keeping.