Psytrance Bass in Serum: The Rolling 16ths Formula That Actually Hits

A psytrance bass isn’t really one sound. It’s a kick and a bass fused into a single pulse — kick on the downbeat, bass firing three 16ths behind it — and if that pulse doesn’t feel like one thing, no amount of processing on the bass alone will save it. The real work is envelope shape, filter slope, and how you carve 40–120 Hz between the two elements. Everything below assumes you’re building for that relationship, not for a soloed patch that sounds cool on its own.

TL;DR

• Two saws, one octave apart, Unison 1, zero detune. This is a mono voice, not a supersaw.
• Amp env: A 0 / D ~120–160 ms / S 0 / short R. Sustain above zero kills the groove.
• LP12 around 200–260 Hz, resonance under 15%. LP24 sounds too clean for psy.
• Sidechain fast attack, release timed so the bass returns exactly as the next 16th hits.
• HPF ~40 Hz on the bass, 3–5 dB dip at the kick’s fundamental, mirror-dip the bass fundamental on the kick.

Build from Init, not from a preset

Menu → Init Preset. Every setting below assumes a clean slate. On Osc A, pull up Basic Shapes and drag the wavetable position to a plain saw. Unison stays at 1. No detune, no blend, no phase randomisation. A psy bass is a single coherent voice a filter can shape predictably — the moment you stack unison on it, the transient smears and the pluck disappears.

Switch on Osc B, same saw, +12 semitones, Unison 1. The upper octave carries the click that lets the bass read over busy percussion and FX. A square works here too — slightly hollower, more nasal — but a saw keeps the harmonic content dense and predictable under the filter.

Leave the Sub oscillator off. This is the single most common mistake in a first psy bass. Your kick already owns everything below 60 Hz; adding a sine to the bass doubles the fundamental every time the bass fires and turns the low end into porridge. In psytrance the low end is a duet. Kick gets the sub, bass gets the mids.

At the bottom of Serum’s interface, set voicing to Mono with Polyphony 1 and Portamento at 0 ms. Poly voices on a 16th roll create overlapping tails that blur the grid. If you want a hint of liquid glide between certain notes, push Porta to 5–10 ms with the Always switch off, so it only slides on legato overlaps in your MIDI.

The envelope is the sound

The amp envelope decides whether your 16ths roll or crawl. Attack: 0 — genuinely instant. Decay: 120–180 ms depending on tempo. Sustain: 0. Release: 20–40 ms.

The maths matters here. At 145 BPM a 16th note is about 103 ms; at 140 BPM it’s ~107 ms; at 150 BPM, ~100 ms. Your envelope has to fully open, close, and leave a gap before the next 16th arrives. Decay too long, the notes bleed into each other and you lose the breathing space that defines the groove. Sustain above zero and any longer note in your MIDI holds flat and cheap.

Fast way to dial it in:

1. Program F1 on every 16th for a bar and loop it.
2. Start with Decay at 200 ms. It’ll sound sluggish and glued together.
3. Pull Decay down until you hear clean daylight between notes — usually 130–160 ms at 145 BPM.
4. Adjust Release last. Too short clicks, too long smears into the next note.

Now the pluck. Drag Env 2 onto the Cutoff knob and set the modulation depth to roughly 15–25% (right-click the modulation ring to type an exact value if you want to be precise). Shape Env 2 tighter than the amp env — A 0, D ~40 ms, S 0. That short filter blip on each note is what your ear reads as “pluck.” Push the depth past 40% and you’re in acid squelch territory, not psy.

Why LP12 beats LP24 here

Set the filter to LP12 (Low Pass 12 dB/octave). Not LP24. The gentler slope leaves more harmonic content above the cutoff, and those harmonics in the 300–800 Hz zone are where the recognisable psy growl actually lives. LP24 sounds cleaner and more “sub-bass polite” — perfect for deep house, wrong here.

Cutoff lands between 180 and 260 Hz. Lower is darker and more tucked; higher is more forward with more of that top-end click. Full-on psy typically leans to the top of that range, progressive and forest to the bottom. Resonance stays modest — 10 to 15%. Any more and you get a peak that becomes fatiguing over a six-minute track. Character should come from Env 2 modulation, not from resonance.

Nudge the filter’s Drive to around 15–25%. Serum’s filter drive adds a subtle harmonic bite that helps the bass cut without external saturation — especially useful when a from-scratch patch feels too polite.

Tune to the kick, not to the key

You cannot design a psy bass in isolation. Drop your kick on the next channel and program the pattern: kick on every quarter, bass on the 2nd, 3rd and 4th 16th of every beat — the “off-off-off” that leaves the downbeat clear.

Now tune. Most psy kicks have a fundamental sitting somewhere between 50 and 70 Hz — a Ableton-native or Zenhiser-style psy kick will often land around G1/A1 (49–55 Hz) after its transient click. Get the kick’s fundamental first (a spectrum analyser with a slow decay works, or just tune it by ear against a sine). Then place your bass an octave below the track’s root, and check that its fundamental sits either well below or well above the kick’s tail — not on top of it.

Loop eight bars and listen for one thing: does the low end feel like a single continuous pulse, or two things fighting? If it’s fighting, either shorten the kick’s tail with a fade or transient shaper, or shift the bass down an octave. Don’t reach for EQ yet — get the tuning and timing right first, then carve.

Browse Psy Trance packs at Myloops →

Sidechain that respects the pattern

Sidechain in psytrance is not the whoosh-pump of progressive house. It’s a surgical duck, active only during the kick hit itself. Put a compressor on the bass — Pro-C 2, Ableton Compressor, or any transparent VCA-style unit — and key it from the kick’s pre-fader send.

• Ratio: 4:1 to 8:1
• Attack: as fast as the plugin allows (0.01–0.1 ms)
• Release: ~80–120 ms at 145 BPM — start here and tune by ear
• Threshold: aim for 6–10 dB of gain reduction per kick

Release is the parameter that makes or breaks it. You want the bass fully back at unity gain right as the next 16th fires — not before (bass punches into the kick tail), not after (uneven volume across the pattern). Program a static 16th roll, watch the gain-reduction meter, and tune release until the needle recovers to 0 dB exactly when each new note triggers.

If your compressor has lookahead, enable it so the attack actually catches the kick’s transient rather than clamping a hair late.

Carving 40–120 Hz so both elements survive

EQ on the bass channel:

• High-pass at 35–45 Hz, 24 dB/oct. Nothing useful lives below this on the bass.
• Bell cut of 3–5 dB at the kick’s fundamental (usually 55–80 Hz), medium Q. Use a spectrum analyser to find the exact spot, not a guess.
• Small bell boost of 1–2 dB somewhere between 800 Hz and 1.2 kHz to bring the pluck forward.
• High-shelf trim above 6–8 kHz only if the sound is fizzy after distortion.

On the kick, do the mirror move: a narrow 2–3 dB dip at the bass fundamental. If the bass fundamental is F1 (~87 Hz), notch the kick at 87 Hz. This is complementary EQ, and it only works because bass and kick are locked in time — each element keeps its body while getting out of the other’s way in frequency.

Check the master with a slow-response analyser (SPAN in “peak” mode, 300 ms average). In a properly balanced psy low end you’ll see the kick spike below 60 Hz, a visible valley in the 60–90 Hz range, and the bass building energy from ~90 Hz upward.

Distortion that adds grit without smearing the low end

A clean psy bass isn’t a psy bass. But where you add the dirt matters more than how much. Inside Serum, engage the Distortion module — Tube, Diode Clip and Down Sample are all worth auditioning. A safe starting point is Tube, Drive 20–30%, with the module’s Pre filter set to a mid band (roughly 200 Hz to 2 kHz) so the harmonics are generated in the growl zone without muddying the fundamental.

If Serum’s distortion doesn’t get you there, a saturator after Serum on the channel will — Saturn 2, Decapitator, or free options like FerricTDS and Softube’s Saturation Knob. Push until the bass sits forward, then back off around 20%. Saturation always sounds bigger in solo than in the mix; trust the mix.

The single most useful move: parallel distortion. Send the bass to a return with heavy saturation, high-pass that return at 250–300 Hz so the dirt lives only in the mids and highs, and blend it in under the clean bass. You get bite and clarity simultaneously, and your low end stays intact.

Programming the pattern so it grooves, not marches

The three-16ths-per-beat skeleton is your foundation, but a static bar looped for four minutes will feel like a machine. Small variations, folded in every 4 or 8 bars, are what keep the ear engaged.

• Drop the last 16th of a bar and let silence carry the transition.
• Pitch a single note up an octave for one bar, then back down.
• Use a legato overlap to trigger portamento between two notes on one beat — Astrix does this constantly.
• Nudge one 16th 2–5 ms late for a hint of human drag.

Velocity does more work than most producers realise. Don’t write everything at 127. Try the three offbeat 16ths at 95, 108, and 120 — a subtle crescendo across each beat that pulls the ear toward the next kick. Then in Serum’s Matrix tab, patch Velocity → Cutoff at ~10%. Now louder notes are also brighter, and a static pattern reads as dynamic without you touching automation.

Movement across the arrangement

Once the core patch grooves, add slow motion so it evolves across a section. Set LFO 1 to a slow rate — 4 or 8 bars per cycle, use Serum’s BPM sync — with a triangle shape, and route it to Cutoff at 5–8%. That gentle brightness wave reads as “the mix is moving” without ever announcing itself.

Then map Serum’s four macros for arrangement-level control:

• Macro 1: Filter cutoff (±20% range)
• Macro 2: Distortion Drive
• Macro 3: Osc B level — blend the upper octave in or out for dynamics
• Macro 4: Env 2 amount — more or less pluck

Now you can automate a single patch across intro, build, drop and breakdown without layering multiple presets. Pull Osc B down and roll cutoff off in a break for a warm, tucked version; push all four up in the peak for full aggression. Same patch, different personalities.

Browse Psy Trance packs at Myloops →

The bottom line

The patch itself is genuinely simple: two saws, aggressive envelope, gentle LP12, a touch of drive. What makes it work is everything around it — the tuning relationship with the kick, the sidechain release timing, the complementary EQ, the velocity feel of the pattern. Producers spend hours tweaking oscillators when the actual problem is that the bass and kick are stepping on each other at 70 Hz.

Build the patch fast, then spend your time on the interaction. Loop eight bars of kick and bass together and don’t move on until that loop feels like a single breathing pulse. Once that foundation is locked, everything you layer on top — leads, pads, atmospheres, percussion — becomes easy, because the low end is already doing its job.

The best psy basses of the last twenty years have all shared this same skeleton. What changes between producers is taste: how much dirt, how much filter movement, how playful the pattern. Get the skeleton right first, then let your taste do the rest.