Modulation

Phaseburn One is monophonic by design, and modulation is what keeps that one voice alive. This chapter collects every mover in the engine: the volume envelope that shapes every note and the percussion engine that sharpens its first milliseconds — both in the envelope panel on the Oscillators tab, whose VOLUME / FILTER / PERCUSSION tab strip also holds the filter envelope — the three LFOs and four step modulators on the Modulation tab, which can reach most of the instrument, and the velocity and aftertouch routes that make playing dynamics count. Filter cutoff has its own dedicated envelope — that one is covered with the filter in the filter chapter (Chapter 3 — The Filter).

Think in sources, not targets

Decide what should move, then give the movement a shape. Phaseburn One’s modulation is source-centric: you do not open a giant routing matrix under a knob — you go to a source (an LFO, a step modulator or aftertouch), and give it destinations. Each LFO and each step modulator carries three routing slots, and aftertouch brings three more, so a patch can run up to twenty-four routes at once. Every slot is a pair: a destination picked from one list shared by all sources, and a bipolar amount — positive pushes the target up as the source rises, negative inverts the movement, and small values matter more than you expect on sensitive targets. Every route is visible from the other side too: the target control draws a modulation ring showing the live range, whichever source — an LFO, a step modulator, aftertouch, velocity, the note-character module or the distortion’s input envelope — is pushing it.

That shared list covers more than a hundred destinations, and the browser presents it the way the panels do: groups in page order, and each group’s entries in the order its knobs sit on the panel — finding a destination is the same gesture as finding its knob. Above the groups it offers the control you last touched, so routing to the knob you just moved needs no search at all. The Phase-Locked Loop (PLL) oscillator exposes its output shape, the multiplier and the divider — each in a stepped and a continuous form — the input-reference blend, its loop controls — track speed, damping and influence — the burst threshold and amount, injection, the chaos drive, the four loop-lab controls (step, grit, lag and relock), FM depth and ratio, and the color stage and its fold ratio. The VECTOR oscillator exposes its X and Y shaping pair, fold and stereo offsets. The MORPH oscillator exposes its morph amount, fold, shape and stereo detune. Each of the three pitched sources also exposes its mixer pan, so a route can place a source off-centre or swing it across the stereo field. Beyond the oscillators (all introduced in the oscillators chapter (Chapter 2 — Oscillators)) the list reaches the filter — cutoff and resonance through to its dry/wet mix — the coloration stages, the delay, the reverb (mix, early-reflection level and wet gain), the chorus, the distortion, the BitCrusher, the freezer (freeze, window, grain, position and mix), and a MIXER group holding the mix-bus level and the master’s stereo width — pumping and widening moves at the very end of the chain. And, unusually, the modulators themselves: every volume envelope stage time, shape, sustain and even three of the velocity routes are destinations, so one source can reshape how another behaves. The freezer’s FREEZE latch is a button-style destination that engages on any positive value, so a bipolar LFO or step lane gates it on its positive half rather than having to cross a midpoint.

When several sources land on the same destination their contributions sum. Amount changes are smoothed, so riding a depth mid-performance never steps audibly; the destination selector itself switches instantly, so pull the amount toward zero first when you re-route a running patch. Coming the other way, right-clicking the target control and choosing Unlink modulation clears every route aimed at it in one gesture — the amounts stay put, so picking a destination again restores the depth that route had. The practical method: build the static patch first, then add one source at a time and give it one clear job — an LFO breathing the filter, a step lane accenting the PLL multiplier, the envelope holding the whole thing together. Because the instrument is a single voice, every route you add changes the one sound you are hearing, which makes cause and effect easy to keep track of — and easy to push much further than a polyphonic patch would tolerate.

The volume envelope

Shape how every note starts, carries and lets go. The volume envelope runs five stages — attack, hold, decay, sustain, release — and attack, decay and release each have their own curve control: at zero the segment is a straight line, negative values bend it into a fast-start logarithmic curve, positive values into a slow-start exponential one. Each of the three also has an S-curve switch that turns the bend into a symmetric ease-in, ease-out shape — the positive half of the shape slider then sets how pronounced the S is, while negative values fall back to a straight line in this mode. Hold sits between attack and decay and keeps the envelope pinned at full level for a moment, which fattens sustained transients without touching the decay itself.

Every timed stage can sync to the host tempo. Flip a stage’s sync switch and its time is derived from a musical division instead of milliseconds, each stage with its own division selector — a release that is always exactly one beat long survives any tempo change. The PLL tail carries the same switch, so a ring-out can be locked to the grid rather than set in milliseconds. The ONE/LOOP button turns the one-shot envelope into a cycling one: while a note is held, attack, hold and decay repeat, which reads as tremolo at short settings and slow rhythmic swells at long ones. Depth blends between the enveloped signal and a constant level — pull it down and the envelope loses its grip, all the way to a steady drone that ignores note shape entirely. Key track shortens the envelope as you play higher and lengthens it lower down, the way acoustic instruments behave.

Because the instrument is monophonic by design, fast lines retrigger the same envelope constantly, and the retrigger behavior is tuned for that: a new note starts its attack from the current level rather than snapping to silence, so runs stay smooth. When you want audible re-articulation instead, raise the retrigger dip — whenever the sequencer retriggers a note while the previous one is still sounding, held or still releasing, it ducks the level before the new attack for a plucked, percussive restatement. Depth buys time as well as depth: at low settings the notch is a brief softening of the retrigger, and as you push it the fall lengthens and then holds at the bottom, so the top of the control is a real gap in the sound — a re-articulation of the note rather than a smoothing of it. A retrigger arriving while a dip is still running keeps the dip in progress instead of ducking again, so fast rolls cannot ratchet the voice down toward silence. The dip acts on sequenced lines only; notes played live over MIDI always take the smooth path. Oscillator phases reset only when a note starts from silence; while the previous note is still sounding, a retrigger leaves the oscillators running, which is part of what keeps fast runs smooth. With legato phrasing, overlapping notes glide without retriggering at all.

The range control — the first slider in the row — is a pure editing zoom: it sets how far the time sliders reach, nothing more. It never changes the sound, and the envelope preview always draws the actual stage times.

Percussion mode

Turn the first few milliseconds of every note into a drum designer. The percussion engine is a dedicated transient system that rides on top of the volume envelope, with three independent tools that fire together at the start of every hit and decay on their own clocks. Every non-legato hit fires: a note starting from silence additionally resets the VECTOR oscillator phase so repeated hits sound identical, while a retrigger over a still-ringing note keeps the oscillators running click-free and simply restarts the transient clocks. Only legato slurs skip the transient entirely.

Sweep is a pitch envelope in semitones. Positive values start the pitch above the note and drop onto it — the classic falling drum attack; negative values rise into the note from below. Time sets how long the settle takes, from a barely-there flick to long drawn-out drops, and curve reshapes the trajectory: negative straightens it into a linear glide that lands exactly on the note, zero is a natural exponential, positive holds the offset and then dives — the zap and laser end of the range. The slider gives half its throw to the musical ±24 st zone, with the extremes still reachable at the ends.

Click adds an onset strike in one of three characters: NOISE is a burst of bandpass-filtered noise, PING a single damped sine at the TONE frequency, and METAL an inharmonic three-partial strike for rim, cowbell and cymbal-adjacent colors. The click deliberately bypasses the volume envelope, running its own short decay, so it punches through even when the envelope attack is slow — the snap arrives first, the body follows. Tone places the strike from sub-thump up into bright cymbal territory, and TRACK tunes it to the played note — at zero the tone stays absolute, at full it rides the pitch line, so clicks stay proportioned across the keyboard. Width shapes character at constant loudness: narrow is a resonant ring, wide a dry thud (in PING and METAL it sets how long the strike rings), and the click has its own decay — short ticks up to snare-scale noise bodies — and curve controls.

T.Fold is extra wavefolding that is strongest at the attack and decays into the clean tone, adding a harmonically dense bite to the first instant of a note. It applies to the VECTOR and MORPH oscillators only.

All three respond to the VEL control, which decides how much MIDI velocity scales their depth — at zero every hit lands full strength, at maximum soft notes barely trigger the transients. The four target switches choose which oscillators get processed, so the sub can stay round while VECTOR takes the fold; on notes that start from silence the VECTOR oscillator uses a fixed phase reset so every hit sounds identical. Reach for percussion mode when you are building kicks, snares, hats and zaps from the synth voice — but also when a bass or pluck patch needs attack definition that the envelope alone cannot give. Most of the percussion controls are modulation destinations too — sweep amount, time and curve; click level, tone, decay and width; fold amount and decay — so an LFO or step lane can vary the drum from hit to hit.

The three LFOs

Give any control a pulse. The three LFOs are identical, run from very slow drift up to a rate that borders on audio, and each drives three destinations, every one with its own bipolar amount. Six waveforms cover the useful space: sine and triangle for smooth breathing, saw for ramps and falls, square for hard toggles, sample-and-hold for stepped random motion (with a small output slew so the steps do not click), and smooth random for wandering curves that never repeat — the organic setting for filter and pitch drift.

Each LFO free-runs at a rate in hertz or locks to the host tempo through a division selector that spans cycles several bars long down to very fast subdivisions, with dotted and triplet variants. The trigger mode decides what a new note does to the cycle: Free ignores notes entirely, Retrigger restarts the LFO from its phase offset for identical motion on every note, and Random Phase starts each note somewhere new for per-note variation. Fade-in ramps the LFO’s depth up after note-on — the standard recipe for vibrato that develops on a held note. One-shot makes the LFO run a single cycle and then hold its final value, which quietly turns any waveform into an extra modulation envelope. The bipolar switch sets the output range: bipolar swings both ways around the target’s set value, unipolar only pushes it one way from where you parked it.

The LFOs can also modulate each other. Pick a source LFO in the cross-mod selector, then blend two effects: phase mod softly pulls the LFO’s phase toward zero on the source’s rising edge — a gentle sync that locks two rates into a rhythmic relationship without hard resets — and rate mod bends the LFO’s speed with the source’s output, up to two octaves in either direction at full amount. A slow sine rate-modulating a fast triangle produces accelerating, decelerating wobbles no single LFO can draw; sample-and-hold rate-modulating anything produces controlled ratchets.

Step modulators SEQ 1 to SEQ 4

When modulation should follow the grid, draw it. Step modulators SEQ 1 to SEQ 4 are four identical lanes on the Modulation tab, each a row of bipolar step values played back at a tempo-synced rate, one step per division, looping at whatever length you set. Each drives three destinations with bipolar amounts, the same routing capacity as an LFO.

What a step lane gives you that an LFO cannot is rhythm as a first-class shape. An LFO repeats one curve; a step lane holds an exact value per grid position, so you can write accents, rests, sudden jumps and asymmetric patterns that correspond to no waveform at all — a filter that opens only on beats two and four, a PLL multiplier that leaps between intervals in a fixed riff. Set the lane length to an odd count against a square sequencer pattern and the lane phases against the bar, a polymeter that keeps a short loop evolving for minutes. Leave retrigger off and the lane free-runs with the tempo regardless of what notes play; switch it on and every note restarts the pattern from step one, tying the modulation to phrasing instead of the bar. Either way, a transport start — pressing Play, or the DAW beginning playback — resets every step modulator to step one of bar one and every LFO to the top of its cycle, so a take always begins the same way.

Two controls decide how steps connect. Ties glide between adjacent steps with a smooth S-curve interpolation — the acid-style slide, drawn per step. Untied steps use the slew control instead: at zero they snap, higher values round every transition. Snap quantizes step values to a twelve-tone grid, which matters the moment a lane drives anything pitch-shaped — the PLL multiplier, the tracked-filter offset, oscillator tuning territory — because steps then land on musical intervals instead of arbitrary values, and ties glide between the snapped levels.

BARS is the pattern’s length in bars. Leave it at one and the lane behaves exactly as above. Raise it and the lane plays bar 1, then bar 2, and so on before looping — each bar carrying its own steps, its own probabilities and its own tie row, and a tie on a bar’s last step gliding into the first step of the next. A strip of numbered segments appears in the panel header as soon as BARS is above one; click a segment to edit that bar, and a dot marks whichever bar the playhead is currently in. Pulling BARS back down hides the later bars without erasing them, so you can try a shorter loop and go back.

TOOLS act on the bar you are looking at. RANDOM, INVERT, MIRROR and CLEAR each apply to the visible bar only — CLEAR included, so emptying a long pattern means clearing each bar in turn. There is no undo on the step lanes, which is exactly why CLEAR is scoped this way. Loading one of the built-in step patterns always sets BARS back to one, because those patterns are single-bar and would otherwise be followed by empty bars.

The four lanes are fully independent, switched with the SEQ 1 to SEQ 4 tabs, and a productive habit is giving each one a clear job: SEQ 1 as a fast rhythmic accent lane, SEQ 2 as a slow, long-loop drift that keeps the patch from standing still, the other two held in reserve for accents you add as the patch grows. SEQ 3 and SEQ 4 are newer than the first pair and default to silence — no destination, zero amount, an empty pattern — so a preset or session saved before they existed loads and sounds exactly as it always did.

The step values themselves are pattern data, not host parameters: they travel with the preset and with your saved project, but they do not appear in the DAW’s parameter list and cannot be automated from a lane there. Everything that shapes the lane — rate, length, bars, slew, polarity, retrigger, snap and the three routes — is a normal automatable parameter.

Velocity and aftertouch

Make how hard you hit part of the patch. Velocity in Phaseburn One arrives from two places: your MIDI playing, and the sequencer itself, which generates velocity per note on its Strength tab. Either way, the same routes apply.

Four bipolar routes feed the volume envelope: velocity to attack, decay, sustain and release. The time routes scale their stage exponentially — with positive amounts, harder hits snap faster and softer hits bloom slower, which is the natural direction for plucked and struck sounds; negative amounts invert the response for pads that open up when you dig in. The sustain route offsets level directly, so hard notes carry more body, not only a faster front. The filter envelope carries the same four routes of its own, plus its own key track, applied with the same formulas — so a note’s brightness can answer touch independently of its loudness; they live on the envelope panel’s FILTER tab and are covered in the filter chapter (Chapter 3 — The Filter). A fifth dynamic control lives in the percussion engine: its VEL parameter scales the sweep, click and fold transients, which turns velocity into hit intensity when you play the synth as a drum. Three of the four envelope velocity routes — attack, decay and sustain — are themselves modulation destinations, so an LFO or step lane can vary how dynamic the instrument feels across a phrase. During legato playing, the velocity lock option keeps velocity pinned to the held note so overlapped transitions do not jump in character.

Aftertouch is the third continuous source. The engine listens to both channel pressure and polyphonic pressure and follows whichever presses harder, then feeds that pressure through three routing slots of its own — each a destination picked from the same shared list, with a bipolar amount, exactly like an LFO slot. Route pressure into filter cutoff for swells that live under your fingers, into VECTOR fold for a growl that answers how hard you lean, or into envelope sustain so held notes bloom under pressure. The first slot lives in the AFTERTOUCH module on the Modulation page; the other two are reachable through the host’s parameter list or automation. These routes travel with the preset. If your keyboard sends no aftertouch at all, an LFO with a long fade-in or a one-shot LFO acting as a slow secondary envelope covers similar ground.

The distortion listens back

The DIST ENV module turns the distortion’s input envelope into a modulation source: how hard the module is being hit at this moment, smoothed and normalized, drives one destination from the shared list with a bipolar amount. It is the classic sidechain trick generalized, keyed on playing dynamics rather than on a gain reduction: route it into filter cutoff and the patch opens as you dig in, into sub volume for a low end that gets out of the way when the drive is working, into delay feedback so echoes stretch out in the gaps. Its route draws a modulation ring on the target like any other source, so you can see the envelope working from the knob it is moving. The envelope is measured one audio block behind the signal that caused it — at modulation rates that is impossible to hear, and it is what keeps the loop of “distortion shapes sound, sound feeds distortion” stable by construction. With the distortion bypassed the source simply sits at zero.