DrumKing — 64-pad sample drum machine

DrumKing is a TheRaK rack instrument: an 8x8 grid of 64 pads, each playing a sample with its own tuning, envelope, filter, two playback effects, a second layer and modulation, in the spirit of Ableton's Drum Rack and Drum Sampler. An STPR-1 in Drum Mode sequences it: one lane per pad, many hits per step, per-hit velocity, probability and ratchets (see Drum Mode in TheRaK). DrumKing lives inside TheRaK only in this update.

Pitches in this guide use scientific pitch: MIDI 60 is C4 and A4 is 440 Hz, so C1 is MIDI 24 (32.70 Hz). Pad notes are given as MIDI numbers; pad 1 plays note 36, the General MIDI kick. The DrumKing card (the grid's bank labels, the pad editor, the pad table, the Kit Root stepper) and the STPR-1 drum lanes name notes the way Ableton does, with the MIDI number beside the name: note 36 is C1 (36), so note 60 reads C3.

1. Open TheRaK (Tools > DAWntless > TheRaK) and choose + Add Device > INSTRUMENT + SEQUENCER > DrumKing + STPR-1 Drum. The console command DrumKing.Open does the same in one step: it opens TheRaK and, when the rack has no DrumKing yet, adds a DrumKing with an STPR-1 (one Undo step). With the device rack turned off, DrumKing.Open changes nothing and says why.
2. The new DrumKing starts with its own copy of the Engine 808 kit, and its STPR-1 plays factory drum pattern A1 (four on the floor).
3. Press Play jam. Unfold the DrumKing card and click pads to hear them; unfold the STPR-1 card to edit the pattern.
4. Choose another kit with the kit browser in the card header (the arrows and the kit name). The factory rack DA_Rack_BloomBeat (DAWntless Content > Examples > Rack) has a DrumKing chain ready to play: STPR-1 Drum → DrumKing (Bloom Studio) → GLTCH.

Pad p (1-64) plays MIDI note Kit Root + p − 1. Kit Root is 36 by default, so the pads play notes 36-99; you can set it from 0 to 64.

• Banks (the default layout): four 4x4 quadrants. A = notes 36-51 bottom-left, B = 52-67 bottom-right, C = 68-83 top-left, D = 84-99 top-right. Inside a quadrant the lowest note is bottom-left, filling rows left to right, as in a drum rack.
• Rows: eight rows of eight consecutive notes, bottom to top.

Notes outside the 64 pads are ignored (and counted). A note-on with velocity 0 is a note-off. The kit's velocity curve bends every incoming velocity first: Linear, Soft (quiet hits louder), Hard (quiet hits quieter) or Fixed (every hit at the kit's fixed velocity).

The grid paints every pad with its colour stripe, a two-line name, its choke group, mute and solo toggles when you point at it, a flash when it plays and an outline when it is selected. Empty pads are dark; a pad whose sample did not load shows Missing sample and its path.

• Click a pad to hear it and select it. The height of the click sets the velocity (40 at the bottom, 127 at the top; Shift plays 127). Ctrl-click toggles a pad in the selection and Shift-click extends it; Space plays the selected pad and the arrow keys move the selection. Auditions go through the powered chain, so they sound while the rack is stopped or playing.

• Drag a pad onto another to swap them. When the STPR-1 has Lanes follow sounds on (the default), its lanes are swapped in every drum pattern in the same Undo step, so the beat keeps its sounds.

• Ctrl-drag copies a pad over another; Alt-drag puts the dragged pad's sample on the target's Layer B, keeping the target's other settings.

• Drop from the Content Browser:

  Drop	Result
  A SoundWave onto an empty pad	Creates a cell named after the wave
  A SoundWave onto a filled pad	Replaces Sample A and keeps every other setting
  Shift + a SoundWave	Sets the pad's Layer B
  Several SoundWaves	Fill the pads upward from the target
  A DrumKing kit	Loads a copy of it, after you confirm
  Anything else	Refused: "DrumKing plays SoundWaves only"

  A wave longer than 10 seconds is accepted with a warning; DrumKing plays at most the first 30 seconds of a wave.

Every gesture is one Undo step. With several pads selected, a knob drag moves all of them by the same amount in one Undo step.

Below the grid, the selected pad's settings are grouped in four tabs; the folded pad table lists every pad with its note, name, sample, choke group, mute, solo, volume and pan.

The header row above the grid holds the kit's volume and tune, the velocity curve, voices (8-64 sounding at once), New, Save and Save As, and the LOADING and MISSED HITS badges.

Kit settings: name, volume (−60..+12 dB), tune (±12 semitones), Kit Root, velocity curve and fixed velocity, voices, choke fade (1-50 ms, 4), layout and the random seed.

Each voice runs: the sample reader (with PitchEnv, FM, Loop and Stretch) → SubOsc and Noise → the other effects in slot order → the filter → the amp envelope and velocity → pan → volume → the kit's volume. SubOsc and FM follow the pad's pitch, which the factory kits measured; a pad you fill yourself assumes middle C (261.6 Hz) for them.

• Layer B plays a second sample with every hit of the pad: it starts Delay ms after Sample A (sample-accurate), sits at the pad's pan plus Pan offset, and decays over the pad's decay times Decay scale. It shares the pad's filter and effects (SubOsc and Noise excepted) and stops, chokes and gets stolen with Sample A.
• Variations alternate Sample A with up to three other waves: Cycle goes A, 1, 2, 3, A...; Random picks any; Random no repeat never plays the same one twice in a row. Random choices follow the kit's seed and restart whenever the transport starts or jumps, so the jam from Play and a printed track from its start choose the same waves.
• Burst retriggers the envelope 1-8 times, the given milliseconds apart, from the start of the sample each time; every hit but the last decays over the burst decay, the last over the pad's decay. That is how the claps are built.

• A hit on a pad in choke group n fades out every other pad of group n over the kit's choke fade (4 ms). Open and closed hats share a group so the closed hat cuts the open one. A muted pad neither sounds nor chokes.
• Max voices limits how many hits of one pad ring at once; the oldest one is cut (quickly faded) for a new hit. At 1 a pad chokes itself.
• Voices (kit) limits how many voices sound at once over the whole kit: a new hit takes a released voice first, then the quietest, then the oldest, which fades out over a few milliseconds instead of clicking.
• A pad re-hit on the same step is never lost: the STPR-1 always sends the note-off first.

Volume, pan, filter frequency and resonance, and mute follow your edits while a pad rings (smoothed over 10 ms, without clicks), as does the kit volume. Every other setting (tuning, envelope, effects, samples) applies from the next hit, so a ringing crash keeps its sound when you edit it. Loading another kit or replacing a sample never cuts the sounds that are playing.

A DrumKing always plays its own copy of a kit. Choosing a kit in the card header, dropping one on the grid, or Reset in the card's [...] menu (back to Engine 808) copies it into the device: the kit asset itself never changes, and rack edits never reach it. New empties the kit. Save writes a kit you saved before back to its asset; Save As (and Save preset... in the card's [...] menu) stores the device's kit as a new asset under /Game/DAWntless/DrumKing/Kits. A rack never writes plugin content. The kit browser lists the factory kits (DAWntless Content > Examples > DrumKing > Kits) and then your kits in /Game/DAWntless/DrumKing/Kits.

Every factory kit uses only sounds that ship with Unreal Engine and its Harmonix plugin; drum sounds those collections lack are shaped from them with the pad effects. Pads 1-16 of the seven drum kits follow General MIDI (36 kick, 38 snare, 42 closed hat, 46 open hat...), so the factory drum patterns play every one of them; Mallets & Plucks is tonal.

Pads 1-16 of the drum kits:

Tuning and level. The tonal pads were tuned by measuring each sample's pitch: every ping-based drum, the Trap Boom 808s, the Dusty Keys EPiano and all of Mallets & Plucks play within 10 cents of their target pitch, and pads that share a sample (the Trap Boom 808 bass, for example) step by exact semitones. Every factory pad was then levelled so that its loudest moment at velocity 127 peaks at −6 dBFS; a pad with variations is levelled on its loudest one, so its other takes play a little softer (the Bloom Studio snare's by about 5 dB). The level differences a kit's design suggests (a ghost snare, a soft pedal hat) therefore come from the pattern's velocities rather than from the pad volumes; turn a pad down in your own copy if you prefer.

Every factory sample, by kit and folder:

Sample names and roots. The pitch of a Harmonix example sample is the MIDI number in its name (the first number: 63 in AGuitar_63_Eb3, 60 in PianoDarkMono_060_C), confirmed by measurement. Several of the note names that follow disagree with that number and are ignored: AGuitar_63_Eb3, AGuitar_68_Ab3 and AGuitar_73_Db3 are really E♭4, A♭4 and D♭5, and EGuitar_73_Db4 is D♭5; the pizzicato strings name MIDI 60 "c3" (the C3 = 60 convention). pizstrings_48_a1 is not used because its name contradicts its pitch. The vibraphone samples sound one octave above their names (Vibes_60 plays C5), so the Mallets & Plucks vibraphone pads play them an octave down to reach C4-D#5.

• DrumKing decodes a kit's samples when its chain powers up (when TheRaK shows the rack, or when a jam, the arrangement or PIE starts it), never while a level or rack loads. Each sample is decoded once and shared by every pad, kit and chain that plays it.
• While samples decode, the card shows LOADING n/m. Play jam waits up to 2 seconds for them. The arrangement and PIE never wait: a hit whose sample is still decoding starts up to 20 ms late, and a later one is skipped and counted under MISSED HITS (and in the log). Missed hits only happen in the first moments after a chain powers.
• A TheRaK Performer playing the rack in a game also waits up to 2 seconds for the samples before its patterns start, without holding up the game (see TheRaK Performer (gameplay)).
• The first time on a new machine. In the editor, the first power of a kit also fetches its compressed samples from the derived data cache, or builds them there, on the editor's main thread. That can take a noticeable moment once per machine and engine version for the larger kits (Mallets & Plucks holds about 17 MiB of decoded audio and Transitions about 12 MiB; all eight factory kits together stay under 40 MiB); later powers are immediate.
• A pad whose sample failed to decode, or whose wave no longer exists, is silent and shows Missing sample with the path. It is not counted as a missed hit.

• DrumKing takes MIDI focus like any rack instrument: note Kit Root + p − 1 plays pad p, while the rack is stopped too.
• The card's (o) bypass silences DrumKing; its STPR-1 keeps running in time.
• Print... writes a DrumKing chain's drum pattern as MIDI notes (see Drum Mode in TheRaK); the printed track owns a snapshot of the chain, kit included, and plays it sample-accurately in the arrangement and in PIE.
• A new Kit Root moves the STPR-1's notes with it at once: the pattern keeps playing the same pads.

• A rack, or a printed track, holds its DrumKing's own copy of the kit, which references its SoundWaves directly; cooking takes them along. No rack depends on the kit assets themselves.
• /Harmonix/Tests may change between engine versions. Bloom Studio, Trap Boom, Dusty Keys, Warehouse and Transitions use the Harmonix plugin's test samples, which Epic can change or remove in another engine version. If a wave disappears, its pads show Missing sample and the path, the kit still loads, and the rest of the kit plays.
• UI Minimal uses editor content. Its VR editor and editor UI sounds (/Engine/VREditor, /Engine/EditorSounds) are left out of a cooked game when Project Settings > Packaging > Exclude editor content when cooking is on: those pads are silent in the game. With that setting on, Validate Assets warns about the kit asset and about every device rack whose DrumKing uses such a kit, and a DrumKing whose waves did not load shows Missing sample for those pads. Load another kit, or turn the setting off, for a packaged game.
• Engine 808 and Mallets & Plucks cook everywhere: they use only /Engine/EngineSounds and the Harmonix example samples. A new DrumKing starts with Engine 808 for that reason.

DrumKing has a pool of 64 voices per chain, of which the kit's Voices (32 by default) may sound at once. A DrumKing with 32 voices sounding uses at most about 300 µs per audio block on the development machine; an idle one costs almost nothing. The card and the chain strip show the chain's CPU time. The decoded samples are 16-bit and shared across the editor (see Loading and missed hits).

• DrumKing lives inside TheRaK only; a standalone kit editor comes later. A MetaSound that uses the DrumKing node outside a TheRaK chain is silent. In a game, DrumKing plays inside a saved rack: through the TheRaK Performer component or a printed track.
• Tempo follow (Stretch or Resample to a source tempo) is stored with each pad but plays as off in this update; no factory kit uses it.
• DrumKing plays at most the first 30 seconds of a wave.