Multisampling and drum-kit instruments

What it is#

One sample cannot cover a keyboard: transposed more than a few semitones it sounds artificial — ±7 at the very most, often only ±1 (source: s-tw084-perfect-samples-the-piano). Multisampling records several keys and maps each note range to its own sample; in impulse-tracker an instrument does the mapping.

The same machinery does a second job that has nothing to do with realism: it puts a whole drum kit on one instrument number, so a snare and a bass drum share one envelope, one NNA and one fadeout.

Building the map#

Two decisions come before any mapping screen.

• How densely to sample. For an acoustic instrument the answer is empirical — every few keys, and more densely where the timbre changes fastest. For a chip the answer is finite and knowable, because the source has a fixed number of states. little-scale's packs show both ends of that range: the C64 SID 8580 and the YM2413 packs take "every C and G note from C-2 to G 6" — two samples per octave, so nothing is ever transposed more than a few semitones — while the SN76489 pack takes 11 pulse archetypes against all 83 pitches and the Atari 2600 TIA pack 14 waveform types against all 32 pitches, one sample per playable value, so nothing is transposed at all (source: s-little-scale-chip-sample-packs). A systematic pack like these is a multisample instrument waiting to be assembled, not a folder of one-shots; his YM2413 naming even encodes the map — odd-numbered files are the Cs, even-numbered the Gs.
• Tune everything to one reference first. Pulse's rule: "tune all samples to one long clear looped reference sample" (source: s-it-hints). A map built from samples that are each a few cents off is a detuned instrument that no note offset can fix. The tuning controls differ by format: S3M/IT/MPTM set the C-5 frequency directly (with a Transpose helper), MOD and XM use finetune — 1/8 of a semitone in MOD, 1/128 in XM — plus a transpose note that MOD locks to C-5 (source: s-openmpt-manual-samples).

How to do it#

Impulse Tracker#

The instrument's note translation table maps every note to a (note, sample) pair, so C-5 01 can play sample 1 while D-5 01 plays sample 3 at D-4. Two uses: a drum kit in one instrument (each note a different drum, one NNA/envelope/fadeout for all; "Update Pattern Data" converts old sample-per-drum patterns), and a high-quality multisampled piano — "if you don't run out of memory first. Or patience." Saving an instrument saves its samples with it (source: s-it-manual).

The kit case is where IT's NNAs pay off: with NNA continue, "put a bass drum in the very next row after [a snare] — the snare will still complete playing" from one instrument on one channel (source: s-it-manual).

FastTracker 2#

An instrument holds 1–16 samples with a key split "drawn" on the piano keyboard; each sample has its own volume, pan, finetune and relative tone; the FAQ warns that the instrument, not the sample, is what carries envelopes (source: s-ft2-manual).

OpenMPT#

The Sample Map lists pattern note → heard note + sample; "for drum sets, simply map all notes to C-5" instead of retuning each sample; XM lacks the note column and allows only 16 samples per instrument; Transpose Samples / Reset Map trades the map for retuned samples so IT portamento between samples behaves (source: s-openmpt-manual-instruments). For chopping one long recording into a map rather than recording separate keys, the sample editor has cue points (MPTM o0x) and slice at cues or grid (source: s-openmpt-manual-samples) — the tidy version of the offset-based approach on sample-offset.

LSDj kits#

The Game Boy's version of a drum-kit instrument, and it is a real map, not a metaphor. A kit instrument names two kits: "the first kit will be used in the left note column in the phrase screen; the second kit will be used in the right note column" — so one instrument addresses two banks of samples, selected by which column the note is typed in (source: s-lsdj-manual). Each kit holds 15 sample slots inside 3FA0 bytes — "just over two seconds worth of audio per kit, so whatever you put in has to count!" — at 11.468 kHz (source: s-little-scale-lsdj-kits; preparation is on chip-samples, patching on lsdpatch).

What that budget forces is the opposite of the IT piano: a themed set is split across slots, not crammed into one. little-scale's own releases show the convention — Mario Paint, "29 samples from the SNES program spread across two kits"; Street Fighter 2, "17 samples in 6 kits"; Street Fighter Alpha, "34 samples in 4 kits with one kit per character". Budget two to six kit slots for a voice or sample set and split by character or function (source: s-little-scale-lsdj-kit-releases).

C64: Digi-Organizer#

The 1980s C64 equivalent, from the other direction: sample definitions are (start page, end page, rate) triples into one block of memory, so a single "instrument" can chain several raw blocks — a poor man's multisample of drum hits, with the map living in the sample table rather than in a note column (source: s-sidin06-digiorganizer).

Recording the samples#

Sample every few keys at the lowest rate that still sounds good; loop the high notes; keep the originals and back them up (source: s-tw084-perfect-samples-the-piano). Necros's 1995 chain: CD player line-out or headphone jack into the GUS/SB line-in, sampled at 22 kHz through fasttracker-2, then ALT-A in ST3 and saved as FT2 .IFF; shielded cables cut the RF noise from monitor, CD player and power supply (source: s-tw015-advanced-tracking-tips-ii). The hardware side — levels, cabling, cards, rates — is on recording-samples (source: s-tw066-sound-recording). For release outside the scene MarkVM (1998) goes further: "as much samples as you can" per instrument at 16-bit/44 kHz, with a downsampled low-quality twin of each instrument for composing and the full set for the final render (source: s-tw114-commercial-tracking-debate; see commercial-tracking).

Sampling a chip is the same job with a cleaner method, because you can enumerate the states: record from hardware, dry, before the console's analogue output stage, at 16-bit/44.1 kHz, normalised and trimmed with fades to stop clicks, and add any filtering in software afterwards — "you can always add a digital filter via software if you so desire" (source: s-little-scale-chip-sample-packs). Murenius's plan to recreate the SID on a hardware synth ends at the same place: a PWM multisample recorded from a C64 emulator (source: s-chipmusic-typical-sid-sounds).

Solo instruments: articulations, not just pitches#

The 1996 realism debate's one concrete recipe. Necros, challenged that a tracked saxophone can never sound real: "you can do a sax right if you know how to multisample" — he uses "10+ samples of bends, hits, overdrives, diff octaves, and keyclick noises" in one instrument; the alternative in his "The Grey Note" is sampled phrases selected with sample offsets ("almost a huge wav file chopped up into ten pieces", Psibelius — see sample-offset). The limit is memory: the variation in tone, attack, dynamics and vibrato of a violin concerto would take "50 megs of samples" (Human), so pick the articulations the part actually uses (source: s-tw070-realism-debate; context on realism-in-tracked-music). A year earlier Necros had listed the instruments that are "DAMN HARD" to sample convincingly — real violins and violas, distorted electric guitars, accordions and harmonicas, trumpets, cornets and trombones — and admitted that loops and riffs were his workaround (source: s-tw009-samples-lameness-preconceptions).

Pulse splits the same idea the other way: rather than one instrument holding every articulation, "create several instruments from one sample for different articulations" — "the reason for why I created instruments the way I did" — and think about how the instrument is actually played, since a real piano "will ALWAYS have more than one note playing" (source: s-it-hints; see new-note-actions, lead-articulation).

Tips & pitfalls#

• Map or transpose, not both by accident. OpenMPT's Transpose Samples / Reset Map exists because portamento between two samples in a map behaves differently from portamento inside one retuned sample; if slides sound wrong across a split point, that is the reason (source: s-openmpt-manual-instruments).
• Envelopes live on the instrument, samples on the map. In FT2 and IT one envelope covers all 16 (or all mapped) samples, which is why a drum kit built this way cannot give the snare and the kick different decays without a second instrument (sources: s-ft2-manual, s-it-manual).
• Split points are audible if the samples are not level-matched. Normalise the whole set together, not sample by sample — and on LSDj push further, because the kit channel is quiet against the others: normalise and then add 3–6 dB (source: s-little-scale-lsdj-kits).
• Two samples per octave is a good default for a chip; one per semitone is better and often affordable when the source has only 32 or 83 pitches to begin with (source: s-little-scale-chip-sample-packs).

Related#

sample-looping · instrument-envelopes · new-note-actions · instrument-design · sample-offset · recording-samples · realism-in-tracked-music · the-grey-note · commercial-tracking · chip-samples · lsdpatch

Sources#

s-tw084-perfect-samples-the-piano · s-ft2-manual · s-openmpt-manual-instruments · s-openmpt-manual-samples · s-tw070-realism-debate · s-tw066-sound-recording · s-tw114-commercial-tracking-debate · s-tw009-samples-lameness-preconceptions · s-tw015-advanced-tracking-tips-ii · s-it-manual · s-it-hints · s-little-scale-chip-sample-packs · s-little-scale-lsdj-kits · s-little-scale-lsdj-kit-releases · s-lsdj-manual · s-sidin06-digiorganizer · s-chipmusic-typical-sid-sounds