Authoring a bass

A bass holds down the low end of a track. It is low in pitch, solid, and usually plays one note at a time. The build is the most direct way to learn how the filter and the amp envelope give a sound its punch, so it is a good first instrument to make from scratch.

Each control below gets a start value and a range to try, and each entry says what happens when you cross an edge. The ranges come from what the instrument is, not from a survey of our presets: on this page, where the note loses its harmonics and collapses into pure sub, and where it stops being a bass and starts being a mid-range synth. See how to read these tables for what the provenance tags mean.

Voice

• Voice Mode (production convention). A bass line plays one note at a time, and Mono makes a new note take over cleanly instead of stacking. Poly only for chordal bass.
• Glide (production convention). At 0 the notes are separate and tight. The slide becomes audible around 0.02 s. Past about 0.3 s the note is still travelling toward its pitch when the beat lands, so the bass reads as late rather than as sliding.

Register

This is the one setting on the page with no room for taste.

• Osc1 Octave (production convention). Producers play bass parts in the comfortable middle of the keyboard, so the preset must put C4 at roughly C2 (about 65 Hz) by itself. Octave -3 is a sub-only bass; anything above -2 is not a bass register.

Do not leave the oscillator high and plan to transpose later. The preset itself carries the low tuning.

Oscillator

• Osc1 Mode (production convention). A saw or square table is the standard bass source. SuperSaw belongs to the reese variant.
• Osc1 WT Pos, when Osc1 Mode is Wavetable or SuperSaw (Kiwisynth-specific, our judgment). Low positions in the factory tables are the darker, simpler waveforms. Harmonic content high up is what makes a bass muddy, and it leaves the filter nothing to do. The physical-model modes do not read a wavetable at all, so on Karplus-Strong, Modal or Granular this control is inert rather than merely set differently.
• Osc1 Unison, when Osc1 Mode is Wavetable or SuperSaw (acoustic fact). Few copies keep one clear pitch. A low note has widely spaced harmonics, so stacking many detuned copies smears the fundamental faster than it would up high. Karplus-Strong and Modal are single-object models, a string and a partial bank, so there is nothing to stack and the control does nothing.
• Osc1 Detune, when Osc1 Mode is Wavetable or SuperSaw (acoustic fact). The beating between copies stays slow enough that the ear still hears a single pitch. Past about 15 ct on a low note the beat turns into an audible wobble and the bass loses its centre. Detune spreads copies that only the wavetable modes create, so it is inert on the physical models.
• Osc1 Width, when Osc1 Mode is Wavetable or SuperSaw (production convention). Low frequencies stay centred. Club systems and vinyl sum the bass to mono, so width in the low end collapses or cancels on the systems that matter most. Karplus-Strong and Modal render one mono object and copy it to both sides, so they are already centred and the control has nothing to spread.
• Sub Level (acoustic fact). The sub sits one octave under Osc 1, so it adds weight below the note rather than the note itself, and it survives whatever the filter removes. With Osc 1 two octaves down, C4 puts it near 33 Hz: felt on a club system, gone on small speakers, which is why the oscillator above it has to carry the pitch. Below about 20% it stops adding weight; past 80% it drowns the main oscillator's character.
• Sub Shape (acoustic fact). A sine sub is pure fundamental and adds no harmonics to fight the main oscillator. Toward square it adds grit but also competes in the range the main oscillator already occupies.
• Warmth (Kiwisynth-specific, our judgment). Kiwisynth-only saturation stage ahead of the filter. Below about 15% it does little; past 50% it thickens the tone enough that the filter has less left to shape.

Filter

Cutoff is the single control that decides how the bass reads, so move it first and move it slowly.

• Filter Type (production convention). A 24 dB low-pass is the standard bass filter: it removes the highs steeply enough that what is left is unambiguously low. MGLow24 is a ladder and thins the low end slightly as resonance rises, which suits an aggressive bass.
• Filter Cutoff, when Filter Type is LP12, LP24 or MGLow24 (acoustic fact). A bass played at C2 has its fundamental near 65 Hz. Below about 150 Hz the filter is cutting into the first harmonics and only the sub survives, so the note is felt but not heard. Past about 1500 Hz the sound occupies the mid range and reads as a synth, not a bass. This band describes a low-pass. The Oil can variant switches the filter to Comb, where the same control becomes a ring pitch rather than a brightness, and none of this applies to it.
• Filter Reso, when Filter Type is LP12, LP24 or MGLow24 (acoustic fact). Resonance emphasises the cutoff peak and gives the squelchy, vocal edge. Past about 60% the peak is a pitch of its own and sings louder than the fundamental, which is an acid lead rather than a bass. On a Comb filter this control stops setting a peak and starts setting how long the tube rings, so the Oil can variant argues for its own value rather than borrowing this one.
• Filter Drive (Kiwisynth-specific, our judgment). Pushes the signal into the filter so the harmonics it adds survive the cutoff.

Amp envelope

• Attack (acoustic fact). A plucked or struck low string speaks immediately. Past about 10 ms the note no longer starts when the key goes down, which the ear reads as late rather than as soft.
• Decay (production convention). With a low sustain this is the length of a plucked bass note. Under about 0.05 s the note is a click; past 1.5 s it stops being an articulated bass line and becomes a held drone.
• Sustain (production convention). The two useful zones are far apart. Under 30% gives a plucked bass that dies while held. From about 60% up gives a held bass that stays solid under the track, and full sustain is right for a sub bass that must not move at all while the key is down.
• Release (acoustic fact). Past about 0.3 s one note is still sounding when the next arrives, and two overlapping low notes are mud rather than a chord, because the ear resolves pitch poorly down there.

Decay and Sustain work as a pair. A short Decay into a low Sustain is a plucked bass. A longer Decay into a high Sustain is a held one.

Movement

Movement over the note: flat, deliberately still across the note (production convention).

A bass part is judged on whether it lands in the same place every time, and movement across the note works against that: a cutoff that is still travelling when the next note arrives makes two identical notes sound different, which reads as an unsteady player rather than as an alive sound. Bass is the category where flat is the right answer, and it is recorded here as a decision rather than left as an omission.

How to build it: Nothing to add. The reese and growl variants are where a bass is supposed to move, and they declare it themselves; the base band does not.

A bass needs less movement than any other sound here, but a little brings it to life. These are routings in the mod matrix.

• Mod Env 1 to Filter Cutoff (acoustic fact). The punch. A struck string is brightest at the instant it is struck and darkens as it rings, so an envelope that opens the cutoff and lets it close is what makes a bass sound played rather than switched on.
• Velocity to Filter Cutoff (acoustic fact). Every real instrument gets brighter when played harder, because a harder strike puts more energy into the upper partials.
• LFO 1 to Filter Cutoff (production convention). The wobble, with the LFO synced to 1/8 or 1/16. Down at 5 to 10% the same routing is a slow drift that keeps a held bass alive instead of a rhythmic effect.

For the punch routing, set Mod Env 1 to Attack 0.001 s, Decay 0.15 s, Sustain 0%, Release 0.1 s. This is a different control from the filter's own Env amount, which follows the amp envelope. Use the mod envelope when you want the filter to close faster than the note does, which on a bass is nearly always.

For a wobble, turn LFO 1 Sync on and set the Division to 1/8 or 1/16 before you set the routing depth.

Effects

• Dist Drive (acoustic fact). Saturation adds harmonics above the fundamental, and the ear infers a low pitch from its harmonics even when the fundamental is missing entirely. This is what lets a phone speaker reproduce a bass it physically cannot reproduce.
• MBSat Mix (Kiwisynth-specific, our judgment). Band-split saturation, so the low end can be driven without smearing the highs.
• Reverb Mix (production convention). Reverb on a low sound blurs the low end and pushes the bass back, when its job is to sit forward and steady. Past about 15% the bass loses its place in the mix.
• EQ Low (production convention). A shelf lift under the fundamental. Past about 6 dB the bass eats the headroom the kick needs.

Variants

A tight bass and a reese are different instruments that happen to share a page. Build the base sound above, then apply the overrides below. Everything not listed stays as it was.

The variants move along two independent axes, and they compose. Timbre is what the note is made of; articulation is how it speaks. A bass can be a reese without growling, can growl without being a reese, and can be both at once. That is why they are separate lists rather than one menu to pick from.

Five timbres and two articulations are listed below. Pick at most one of each. The struck metal timbre is the clearest case for why the axes are kept apart: on its own it says the note is made of metal and says nothing about how long it lasts. Put it with the plucked articulation and the metal dies while you hold the key. Put it with the base envelope and the same metal sustains. Same material, different instrument.

Reese

What the note is made of (timbre). Everything not listed below is unchanged from the base bass. A preset claims this band by declaring "timbre": "reese" in its tags; until it does, the base band still applies to it.

The beating between the copies becomes the sound itself, rather than something to keep under control. There is little useful ground between this and a tight bass: around 20 to 30 ct a bass is too smeared to be tight and too clean to be a reese.

• Osc1 Mode (production convention). A ready-made stack of detuned saws is the classic reese source.
• Osc1 Unison (production convention). Enough copies that the beating is dense rather than a pair of notes fighting.
• Osc1 Detune (production convention). Past about 30 ct the copies stop reading as one pitch and the interference pattern becomes the timbre. That is the reese.
• Osc1 Width (production convention). The width is the point here, and the mono rule is relaxed because a reese is a mid-range sound sitting over a separate sub.

Plucked bass

How the note speaks (articulation). Everything not listed below is unchanged from the base bass. A preset claims this band by declaring "articulation": "plucked" in its tags; until it does, the base band still applies to it.

The note dies while you are still holding the key, the way a real plucked string does.

• Sustain (acoustic fact). A plucked string has no sustain: all its energy arrives at the strike and drains away.
• Decay (acoustic fact). The decay is now the entire length of the note.

Growl bass

How the note speaks (articulation). Everything not listed below is unchanged from the base bass. A preset claims this band by declaring "articulation": "growl" in its tags; until it does, the base band still applies to it.

A growl bass is not played as a line. It is one held note a bar, or one a phrase, and it is the only bass articulation where a slow attack is right: the note swells into the honk instead of arriving at it. This is what the base band forbids, and the base band is correct to forbid it. Do not reach for these numbers for a bassline. At the 60 ms start value, a 16th note at 130 BPM is a third of the way through before the note reaches full level, and the part reads as late rather than as heavy.

• Attack (production convention). Under about 30 ms there is no swell left and the growl just starts, which throws away the whole gesture. Past about 100 ms the note is audibly late even against a half-note bassline, and the swell stops reading as intent and starts reading as a slow envelope.
• Release (production convention). The base band stops at 0.3 s because two overlapping low notes are mud. That still holds, and it is exactly why this articulation is only safe on a part with room around it: the ring is affordable when the next note is a bar away, and it is mud the moment it is not. Past about 0.6 s the tail outlasts even a whole-note part.

Before you pick a metal timbre

The next four headings are not four ways of setting one control. They are four different metallic materials, and they disagree about how metal should behave. Before picking one, there is a rule all four obey.

Metal is inharmonic: its partials are not whole-number multiples of the note you played. That is what makes it read as an object rather than as a tone. Down in the bass register it is also what makes it read as mud, because partials that close together below 200 Hz stop being separable and just sound wrong. So the weight and the metal have to be different layers. Keep the Sub harmonic, centred and untouched, put the metal above it, and filter them apart with Filter Routing set to Split, which sends Osc 1 and Osc 3 through filter 1 and Osc 2 with the Sub through filter 2. Skip that separation and every recipe here collapses into the same muddy result.

Then pick by what you want the note to do. Flexing metal bends while it rings and is the only one where the movement is the sound. Oil can gets a similar flex from a swept pipe instead of moving partials. Tensioned bell sustains and drifts. Struck metal is hit and left alone.

Flexing metal

What the note is made of (timbre). Everything not listed below is unchanged from the base bass. A preset claims this band by declaring "timbre": "flexing" in its tags; until it does, the base band still applies to it.

A sheet of metal under changing tension. The partials are not whole-number multiples of the played note, and they move while the note rings, which is what separates bending metal from a struck bell. Modal Inharm is the control that does it, and it is the one to automate rather than set and leave. Keep the metal above the fundamental: a partial bank anchored at the played pitch radiates almost nothing below it, so the Sub carries the register on its own and the two must not be filtered together.

• Osc1 Mode (Kiwisynth-specific, our judgment). The modal resonator is the only source here whose partial spacing is a control rather than a property of a wavetable. Nothing else in the engine lets you retune the partials without retuning the note.
• Osc1 Modal Inharm (Kiwisynth-specific, our judgment). Under about 15% the partials are close enough to whole-number multiples that the bank reads as a dull sine stack and the metal disappears. Past about 75% the partials are so far from the fundamental that they stop implying it, and the bass loses the sense of playing a note at all.
• Osc1 Modal Damp (Kiwisynth-specific, our judgment). Under about 25% the ring outlasts the note and successive notes pile into each other in the register where that is least forgivable. Past about 70% the partials die before the bend has anywhere to travel, which throws away the reason for the variant.
• Osc1 Modal Pos (acoustic fact). Where the sheet is struck decides which partials get energy at all, and a strike on a node cannot excite that partial. Near the edge every partial speaks. At the centre the even partials are killed outright and what is left is hollow rather than metallic. Set before the note: this one describes the strike, so unlike the two above it does nothing once the note is sounding.
• Sub Level (acoustic fact). The partial bank starts at the played pitch and puts nothing underneath it, so the Sub is not reinforcing the low end here, it is the whole low end. Below about 45% the patch is a metallic mid-range sound with no bass in it.
• Filter Routing (Kiwisynth-specific, our judgment). Split sends Osc 1 and Osc 3 through filter 1 and Osc 2 with the Sub through filter 2, which is the separation this sound needs: shape the metal without touching the weight. Filtering both together is what makes an inharmonic bass read as mud.
• Filter 2 Type (Kiwisynth-specific, our judgment). Split needs a filter 2 to split into. With Filter 2 Type at Off the engine collapses Split back to the single-filter path (Voice::applyFilters) and the Sub is filtered with the metal after all, which matters more here than anywhere: the partial bank puts nothing under the played pitch, so the Sub is the entire low end and shaping it with the metal is what the routing row above exists to avoid.
• Mod Env 1 to Osc1 Modal Inharm (acoustic fact). The bend, and the reason this variant is not the tensioned bell. A sheet stiffens as it deflects, so the partials sit furthest from whole-number multiples at the strike and settle back as the note rings. ModEnv1 is what moves them: depth is a fraction of the full control here, so 20% pushes Inharm 0.2 above its resting value and releases it. Past about 35% the peak leaves this variant's own inharmonicity band, and the partials stop implying the fundamental at the one moment the ear is trying to work out what note was played.
• ModEnv1 Atk (acoustic fact). The tension arrives with the strike, not after it. An audible attack here bends the partials outward while the note is already sounding, which reads as a modulation applied to a bell rather than as the strike that tensioned the sheet.
• ModEnv1 Dec (acoustic fact). The bend has to finish inside the ring, so this is bounded by Modal Damp above rather than by the tempo: at damping 0.45 the partials are still audible for a second or two, and a bend that outlasts them is a bend nobody hears the end of. Longer than the ring and the variant reduces to a static inharmonic tone that happens to have started moving. Slower than a can because the sheet is larger and relaxes further.
• ModEnv1 Sus (acoustic fact). Set and leave is the exact failure this variant is defined against. Sustain above zero holds the partials at the bent tuning for as long as the note is held, which is a static inharmonic tone: the tensioned bell, reached by accident and with none of that variant's control over where the sidebands land.

Modal Inharm is the control to automate rather than to set, and the table says what to automate it with: Mod Env 1, fast in and slow out, so the partials sit furthest from the harmonic series at the strike and settle back while the note rings. That is the difference between metal being bent and metal that was already bent when you found it. Sustain has to be zero for the same reason it does on the oil can, because a held bend is a static inharmonic tone, which is the tensioned bell further down this page and not this variant. An MSEG works in place of the envelope if you want to draw the shape of the relaxation by hand.

The ends of the band are positions, not destinations. The gesture lives in the middle of it.

Modal Pos is the exception on this list. It describes where the sheet was struck, so it only does anything at the moment the note starts. Automating it does nothing, by design, in the same way you cannot change where you hit a bell after hitting it.

Oil can

Hit an empty steel drum with the flat of your hand. You get a dull thud from the air inside and a bright metallic ring on top of it, and the ring does not hold still: it starts sharp and slides downward as it dies. That glide is the sound. A thin sheet stiffens the further it deflects, so the hardest part of the strike is also the most in tune with itself, and the pitch falls as the sheet relaxes. It is the same family as a thunder sheet or a steel pan struck before it has settled: hollow, pitched, and unstable in pitch in a way no solid object is.

Two things follow, and they are what the table below is for. The ring is hollow rather than full, because a drum closed at one end favours the odd partials. And the glide is neither vibrato nor a filter sweep: it is the resonator changing size while the note rings.

What the note is made of (timbre). Everything not listed below is unchanged from the base bass. A preset claims this band by declaring "timbre": "oilcan" in its tags; until it does, the base band still applies to it.

The sound of a thin sheet flexing, made by sweeping a tuned pipe rather than by retuning partials. Set Filter Type to Comb and Comb Mode to Closed, then automate the cutoff. On a Comb the cutoff is not a brightness at all, it is the pitch the pipe rings at, which is why the base bass cutoff band does not apply here and the movement row below is doing the work.

• Filter Type (Kiwisynth-specific, our judgment). The comb is a delay with feedback, so it rings at a pitch set by the delay length. Sweeping that length is the flex. No other filter type in the engine has a pitch to sweep.
• Comb Mode (acoustic fact). Closed models a quarter-wave pipe stopped at one end, which rings on odd harmonics only. That gap where the even harmonics should be is what the ear hears as hollow struck metal rather than as a filtered saw. Open is the fuller half-wave pipe and reads closer to a flanger.
• Filter Cutoff (Kiwisynth-specific, our judgment). Read this as the pipe's pitch rather than as brightness, and specifically as the pitch the pipe comes to rest at: the movement row below starts the note above this value and glides down onto it. Below about 90 Hz the ring sits under the fundamental and thickens the note instead of colouring it. Past about 700 Hz the ring separates from the bass and reads as a second instrument playing along. One thing the number cannot carry on its own: cutoff is keytracked, so 180 Hz is 180 Hz at C4 and 360 Hz an octave up. A real can rings at whatever pitch its own sheet decides, whatever you hit it with, so route Keytrack to Filter Cutoff with a negative depth if you want the pipe to stay put across the keyboard.
• Filter Reso (Kiwisynth-specific, our judgment). Resonance is the pipe's feedback, so it sets how long the ring sustains and how strongly the sheet reads as metal rather than as a filter sweep. Under about 45% there is not enough ring to hear a pitch. The engine caps the loop just below self-oscillation, so the top of the range is loud and long but will not run away.
• Comb Damp (acoustic fact). Damping rolls the upper partials off the ring as it decays, the way a real pipe loses its highs first. At 0 the ring stays bright the whole way down, which is the giveaway that it is a delay line and not an object.
• Filter Routing (Kiwisynth-specific, our judgment). Same reason as the flexing variant: Osc 2 and the Sub go through filter 2, so the low end stays out of the comb. A comb swept across the fundamental will otherwise cancel the note it is supposed to be colouring.
• Filter 2 Type (Kiwisynth-specific, our judgment). Split does nothing on its own. With Filter 2 Type left at Off the engine collapses Split back to the single-filter path (Voice::applyFilters), and the Sub goes through the comb after all, which is the one thing the routing row above is there to prevent. Filter 2 exists in this recipe only to make the split real, so leave its cutoff open and let the low layer through unshaped.
• Mod Env 1 to Filter Cutoff (acoustic fact). This is the whole variant. Strike a thin sheet hard and it stiffens: the larger the deflection the higher the tension, so the ring starts sharp and falls as the deflection dies away. That descending glide is what the ear identifies as a can rather than as a filter. Depth is a linear offset here of about 400 Hz per unit, so 20% starts the pipe about six semitones above its resting pitch. Under about 9% the glide is a few semitones and reads as a click. Past about 45% it is a full octave and starts to read as a pitch-bent second voice.
• ModEnv1 Atk (acoustic fact). A strike has no attack time. Anything audible here sweeps the pipe upward into the note first, which is a rising filter gesture and the opposite of the sound: the note has to arrive already stretched and then relax onto its resting pitch.
• ModEnv1 Dec (acoustic fact). How long the sheet takes to relax, and therefore the length of the glide. Under about 90 ms the pitch move is too fast to hear as a bend and reads as an attack transient. Past about 600 ms the pipe is still moving when the next note lands, and two overlapping glides in the bass register read as an instrument out of tune rather than as one piece of metal.
• ModEnv1 Sus (acoustic fact). The sheet has to come to rest. Any sustain holds the pipe permanently stretched for as long as the note is held, so the glide ends on a pitch that is not the pipe's own and the note never settles. This is also what makes the resting cutoff above mean what it says.

The cutoff on a Comb is not a brightness. It is the length of the pipe, and therefore the pitch it rings at, which is why the base bass cutoff and resonance bands say nothing about this variant.

Set the cutoff to the pitch you want the pipe to end on, then let Mod Env 1 carry it down onto that value. Two settings decide whether this reads as an object or as an effect. Sustain has to be zero, or the pipe never comes to rest and you are listening to a filter held open. And Filter 2 has to be on: with Filter 2 Type at Off the engine treats Split as Series, the Sub goes into the comb with everything else, and a comb swept across the fundamental cancels the note it is meant to be colouring. Leave the envelope out entirely and there is no oil can at all, only a static hollow filter on a bass.

This is the recipe to reach for when the note has to keep its own pitch clearly. The metal here is a colour laid over an ordinary bass rather than a replacement for its tone, so the bassline still reads as a bassline.

Tensioned bell

What the note is made of (timbre). Everything not listed below is unchanged from the base bass. A preset claims this band by declaring "timbre": "bell" in its tags; until it does, the base band still applies to it.

The most sustained of the metallic timbres, and the one to reach for when the bass has to hold a note rather than speak and die. FM with a deliberately off-integer ratio puts the sidebands where no harmonic series would, and a ratio offset a little away from 1.0 beats the modulators against the carriers so the metal drifts slowly instead of standing still.

• FM Mode (Kiwisynth-specific, our judgment). Phase modulation is the only route to sidebands that are not harmonics of the played note, which is what makes the tone read as struck metal rather than as a bright saw.
• FM Algorithm (Kiwisynth-specific, our judgment). Dual Pair runs a second sine pair into Osc 3, so there are two independent inharmonic sources rather than one. Two Op Stack is the simpler classic pair and gives a thinner, more predictable metal.
• FM Depth (Kiwisynth-specific, our judgment). Depth is how far the sidebands spread. Under about 15% the tone is a slightly bright sine and the metal has not arrived. Past about 55% the sidebands are dense enough to read as noise, and in the bass register that is indistinguishable from distortion.
• FM Op4 Ratio (acoustic fact). Whole-number ratios give harmonics and therefore a tone, not a bell. The point is to sit near a whole number without landing on it: the partials then fall between the harmonics of the played note, which is the defining property of a struck metal object. How far off matters more than which number.
• FM Ratio Offset (Kiwisynth-specific, our judgment). This detunes the modulators against the carriers, so the sidebands beat slowly and the metal drifts rather than standing still. At exactly 1.0 the tone is static. Past about 1.006 the beating is fast enough to read as vibrato, and a bass with vibrato on it stops sounding like an object under tension.

The two ratio controls do different jobs and it is worth keeping them apart. Op4 Ratio decides where the partials sit, and the useful values are the ones near a whole number without landing on it. Ratio Offset decides how fast the whole structure beats against itself, and it is the reason a held note keeps moving without any modulation routed to it.

Of the four this one sustains best, so it suits a bass that holds under a chord. It is also the one that turns to noise fastest if the depth is pushed, and in the bass register dense sidebands are indistinguishable from distortion.

Struck metal

What the note is made of (timbre). Everything not listed below is unchanged from the base bass. A preset claims this band by declaring "timbre": "struck" in its tags; until it does, the base band still applies to it.

A length of metal hit rather than bent. This is a timbre, not an envelope: it says what the note is made of and says nothing about how long it lasts. Pair it with the plucked articulation for something that dies while you hold the key, or with the base envelope for a struck note that sustains. That pairing is the whole point of keeping the two axes apart.

• Osc1 Mode (Kiwisynth-specific, our judgment). Karplus-Strong is an excited delay line, so it models something hit and left to ring. Its decay stretch control is what pushes it from string toward metal.
• Osc1 KS Stretch (acoustic fact). Stretch decides how much longer the low partials ring than the high ones. A string loses its highs quickly and settles into its fundamental. A metal bar holds its upper partials far longer, and that difference is most of what tells the ear which material it is hearing. Under about 50% the ear hears a string.
• Osc1 KS Damping (acoustic fact). Metal is a low-loss material and keeps ringing after it is hit. Past about 55% the note is dead too fast to have been metal at all, whatever the stretch says.
• Osc1 KS Brightness (acoustic fact). Brightness sets the spectrum of the strike itself. A hard object striking metal is a wideband click, and a dull excitation leaves the upper partials unexcited no matter how long they could have rung.
• Pick Attack (acoustic fact). The noise transient is the sound of contact, and struck metal is mostly identified in its first few milliseconds. Without it the note fades up into a ring and reads as synthetic. Past about 70% the click is a separate event in front of the note rather than part of it.

KS Stretch is what makes this metal rather than string. A string sheds its upper partials quickly and settles into its fundamental; a metal bar holds them far longer, and the ear uses that difference to decide what it is listening to. Pick Attack supplies the contact noise, and struck metal is mostly identified in its first few milliseconds, so leaving it at zero costs more than the number suggests.

This timbre carries no envelope of its own. Combine it with the plucked articulation above for metal that dies while held, or leave the base envelope in place for metal that rings on.

Driving any of them harder

This one is not a variant and has no table of its own, which is the point of putting it here. None of the four needs a separate aggressive variant, because aggression is not a different material. It is the same material driven harder, and it stacks on top of whichever timbre is already in place rather than replacing it.

Two controls do most of it. Dist Drive is already in the base Effects band, and the top of that band is a long way from clean. Setting Dist Mode to Decimate instead of a clipping curve adds sample-rate reduction, which lays bright digital aliasing over the partials and suits metal better than a smooth clip does, because the aliasing is inharmonic too and reinforces what the timbre is already doing.

For movement that reads as violence rather than as wobble, drive the timbre control from a step sequencer instead of an LFO. Stepped jumps between partial structures sound like a sheet being struck repeatedly under tension. A smooth LFO on the same destination sounds like a filter sweep, which is a different and much older effect.