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Generic / PC trackers cheat sheet

Generic tracker sections of the technique pages · print · built 2026-08-31

Techniques

Chip samples — tiny looped waveforms › Trackers with real chips #

On the C64 and Game Boy the "sample" is the instrument definition itself — see instrument-tables and wavetable-programming; the closest PC-tracker equivalent to pulse-width-modulation is switching between pulse chips of different widths (s-037-lab).

The C64 has a sample channel of sorts too — the digi, or volume-register sample: the 6581 "produces a DC output with its intensity being regulated by the global volume register", so writing 4-bit sample values to it fast enough gives "a crude, virtual fourth 4-bit PCM channel"; furnace offers this as the system Commodore 64 (SID 6581) with software PCM and notes that the 8580 "fixed this problem, making such PCM nearly inaudible" (source: s-furnace-c64-docs). commodore-64.eu calls it the "sample bug" and names Ghostbusters and Arkanoid as games that used it (source: s-commodore-64-eu-sid-chip; secondary). SID musicians also use looped samples the way PC chiptunes do: in Gallefoss's Electronic Transfer "the bass tone is a sample loop (like how chip modules do it)" (4mat, source: s-chipmusic-sid-music-hints-n-tips). Background on sid.

How the composers used it:

Detune › PC trackers #

Vivid's flange/chorus: the same sample on two channels, the second delayed by a sample offset (9xx) or note delay (EDx), with a fine pitch slide (E1x/E2x in ProTracker) on one of them to control the beating — "works pretty fine on brass leads" (source: s-tw059-tracking-hints). Zinc's stereo doubling with two slightly different samples, or the same sample slightly offset, panned apart, is the same idea across the stereo field (source: s-tw075-it-percussion-tips). A permanent detune is a different tuning on the duplicated sample, and the unit depends on the format (sources: s-protracker-23d-help, s-st3-manual, s-st3-tech-doc, s-ft2-manual, s-openmpt-manual-samples): ProTracker finetune −8…+7 shifts A from 412.0 Hz to 457.0 Hz in steps of roughly 1/8 semitone (0 = 436.4, +1 = 439.0, +2 = 441.6 …), also settable per note with E5x; ST3 replaces it with C4Spd, the frequency at C-4 (8363 = none; S2x maps the MOD values to 7895–8757 Hz; +/- on the field halve or double it, / sets it by note); FT2 widened finetune to a signed byte, 1/128 semitone (audible in steps of 8), plus a relative tone; IT/OpenMPT set the C-5 frequency directly. Fine pitch slides (E1x/E2x) are "Great for creating chorus effects" (ProTracker), and MPTM has +xx for a per-note finetune.

StereoMan's IT flanging: the same sample on two channels at exactly the same pan, one with a fine pitch slide (EE1, or volume-column u11… then u00); put the pair at X00/XFF instead for a three-dimensional sound (source: s-it-hints).

Fake echo / delay › Any tracker #

Copy the melody column, paste it 3 or 6 rows lower into a free channel (or into the gaps of the same channel), lower its volume, and optionally use a duller instrument.

Fake echo / delay › Sample trackers #

The "standard techno echo" of the 1990s PC scene: copy a column to another channel with an offset of 2 or 3 rows and lower its volume (GBlues, source: s-tw055-panning-debate); pan the echo to the other side of the source, or spread several echoes across the stereo field (Vivid, source: s-tw059-tracking-hints). Alternatives when channels are short: impulse-tracker's retrigger Qxy with a volume decrease, or a looped reverb tail shaped by a volume envelope so the "echo" lives inside the instrument (instrument-envelopes; source: s-tw081-it-tip-of-the-week). Necros's numbers for a lead echo (source: s-tw012-advanced-tracking-tips): copy the track, ALT-J its volume to at least a third lower — 22 from 64; "I hate leads where people copy the track, move it down, and forget to drop the volume" — and offset it two or three rows at speed 6, four or six at speed 3 so the delay sits on the beat; pan it the same distance on the other side of the lead, or hard on the lead's own side (stereo-panning, lead-articulation).

The manuals' own echo tools (sources: s-st3-manual, s-protracker-23d-help, s-ft2-manual): ST3's block mix — "set the skip level to 2 and write the melody. Then copy the melody to an adjacent channel, lower its volume with ALT-J, insert it one row, and mix it with the original melody"; Alt-I/Alt-J multiply volumes by 3/2 or 2/3 "for creating echoes". ProTracker: ED0 delays a note "a little anyway. You can play the same note on two channels, delay one, and get a nice flanging effect", the Edit Op Echo function bakes an echo into a sample ("If you want more room to echo in, just turn up the length of the sample"), and Ctrl+J join-pastes a block over existing notes. FT2's sample editor extension has an Echo command too.

Airon (1998) calls this channel echo "a primitive version" of a reverb's early reflections; the real thing has to be baked into the sample offline — see reverb-and-compression (source: s-tw118-reverb-and-compression).

Instrument design beats note count › Sample trackers #

  • Drums: make chip drums by cutting both ends off real drum samples until they are tiny (source: s-tw077-chip-off-the-block); tune percussion by setting the sample's C-5 speed and always playing one note; kick in the centre; volume swing on hi-hats; keep sample volumes relative and balance with the global volume (Zinc, source: s-tw075-it-percussion-tips).
  • Sample prep: centre (ALT-H) and amplify (ALT-M) in IT (source: s-tw081-it-tip-of-the-week); filter out what a sound doesn't need — "why should a bassdrum have high frequencies?" — and add reverb offline, then pan the echoes (Vivid, source: s-tw059-tracking-hints); tune melodic samples with a guitar tuner on the line-out (source: s-tw077-general-tracking-tips); offline reverb and compression — threshold/ratio/attack per sound, gated-reverb and preverb recipes — are on reverb-and-compression (source: s-tw118-reverb-and-compression), the recording chain on recording-samples (source: s-tw066-sound-recording).
  • Instruments, not just samples: NNAs for sustain in one channel (new-note-actions), envelopes for reverb tails, sirens and analog sweeps (instrument-envelopes); several cheap instruments per sample.
  • Realistic instruments come from sampling a real synth (Behemoth's Korg X5) — the opposite aesthetic to chip-samples, same craft (source: s-tw076-realism-in-mods).
  • Where the samples came from (1995–96), per the traxweekly interviews: CDs and a friend's synth (basehead; source: s-tw001-interview-basehead); own CDs and videotapes through Goldwave 2.1 or CoolEdit (maelcum; source: s-tw009-interview-maelcum); a full own-synth chain — Korg Poly-61, Roland JX-8P, Yamaha DX7, Yamaha FX-500, an SM57 and a small mixer — for 99 % of one group's samples (the-zapper; source: s-tw027-interview-zapper); a whole song from a Casio CZ-101 (skaven; source: s-tw109-interview-skaven); the #trax wish list of December 1996 — Roland XP-50, Korg Prophecy, Korg Trinity, K2500, Nord Lead (source: s-tw080-trax-mass-interview). The ripping ethic of the same interviews: fine if you lack equipment, lazy if you have it, always credit (zinc; source: s-tw032-interview-zinc); "technique is technique, all that matters is the vibe" (jugi; source: s-tw010-interview-jugi) — see sample-ripping.
  • Why the PC scene chose samples at all, from two later interviews: Mental Floss, after buying a Yamaha CS1x, "just had to go back to tracking. Synths are nice, but you just have a bigger sound stock by using samples, and more control" — and names what samples still lacked in 1998, "A) A sampler with filters B) An effects box" (source: s-tw119-interview-mental-floss). The flip side is that the instrument is the sample: for tracked techno, "with good samples, you can make stuff that sounds like real vinyl" (Injekted), and the main problem with scene techno is "lots of bad samples" (Subhuman) (source: s-tw054-interview-injekted-and-subhuman).
  • Palettes and sample sets in the interviews (1995–96): a fixed palette as a writing method — perisoft's three standby samples, "FC SINER FROM PANIC", a "FILTER SYNTH" and the lead from Insideout, gave him ten songs in two weeks (source: s-tw011-interview-perisoft; compare chip-samples); new samples as the creativity trigger — beaner: "without new samples, i have absolutely NO creativity" (source: s-tw011-interview-beaner) — against big-jim's warning that spending the time on samples and rushing the tracking "gets boring half way through" (Foreign Skys; source: s-tw013-interview-big-jim); sample sets travelled with a style — lord-pegasus used "like 50% bh samples" and was told he tracked like basehead (source: s-tw018-interview-lord-pegasus), and maelcum claimed the "rezonant bassy sounds floating around nowadays" as his own, uncredited (source: s-tw019-interview-quarex); u4ia's criterion for a vocal sample is a voice that "alters much like an analog synth does. The sound progresses instead of sounding the same all the time" (Annie Lennox, "diva" voices), and his advice is "distort your samples and be happy" (source: s-tw067-interview-u4ia).
  • Drum sampling (the sincere part of a satirical series, source: s-tw087-music-theory-a-modern-approach): sample drum machines in a pawn shop or real drums; study commercial drum loops closely — their main pulse is often a tambourine, so sample one; sample kick-plus-snare combinations in one file (playing them separately with NNA continue in impulse-tracker "loses the subharmonics and resounding frequencies as the two waveforms interact"); prefer a splash to a crash; render a pattern to a sample, drown it in reverb (Sound Forge, Cool Edit, GoldWave), then record to tape and resample for "analog noise".

Three tool-level recipes from the manuals: ProTracker's Chord maker mixes major, minor, sus4, 6th and 7th chords of one sample into a new chord sample (the way a 4-channel MOD gets a full chord on one channel), and its Boost/Filter/Echo shape drum samples ("Boost … Use this on hi-hats and snares!"; Filter "on noisy basses") (source: s-protracker-23d-help); FT2 builds instruments from envelopes, auto-vibrato and key splits (instrument-envelopes, multisampling; source: s-ft2-manual); S3M and OpenMPT's MPTM add two-operator FM patches — opl-fm-instruments (sources: s-st3-manual, s-openmpt-manual-samples).

New Note Actions (NNA) › Other trackers #

XM has no NNAs — the FT2 manual defines an instrument as envelopes, auto-vibrato, samples, key split and MIDI, nothing more, and the Schism FAQ's "Tell the Milky Tracker guys to add NNAs ;)" makes the same point about FT2-style trackers (sources: s-ft2-manual, s-schism-tracker-wiki). openmpt implements IT's in full — Note Cut (default), Continue ("mostly useful with short one-shot samples such as percussion"; looped samples continue "indefinitely until you trigger one of the 'Past Note' effects S70, S71 or S72"), Note Off, Note Fade (equals Continue when Fade Out is 0) — plus Duplicate Note Checks by note, sample, instrument or plugin with their own action, and calls NNAs "a great way to save pattern channels that would otherwise be used just fading out playing notes" (source: s-openmpt-manual-instruments). Chip trackers have nothing comparable — the chip has no spare voices, which is why channel-interleaving exists.

Octave bass › Any tracker #

Type the pattern by hand (C-2 C-3 C-2 C-3 …) or, where the tracker has an arpeggio command, run a two-note arp 0 12 at 8th/16th rate (chord-arpeggio).

OPL / AdLib FM instruments in trackers › Before the trackers: EdLib and a C64 composer's AdLib player #

The scene did not only reach OPL through trackers. JCH's route is documented in detail and is worth reading as design notes for FM sequencing (sources: s-chordian-my-computer-chronicles, s-chordian-player-editor-notes).

  • The player (November 1991) carried the C64 habits straight over: arpeggio tables in the C64 style, his own vibrato and modulation control — "it immediately distanced the player from almost anything that used AdLib on the PC" — and a timer interrupt instead of raster sync, since the PC has no raster to hang a player on (multispeed, sid-player-routine).
  • "Register bypassing", his own invention and the one idea here that any OPL player still needs: cache every OPL register write and skip the ones whose value has not changed. The chip is addressed through a slow port pair, so the win is real, and it is the FM equivalent of the ghost-register tricks the SID drivers use (instrument-tables).
  • EdLib, the DOS editor grown out of a "Multi-Editor" prototype, used "the same sequence editing principle as on the C64", folding out only the selected one of nine channels — nine being exactly the OPL2's melodic voice count. First version September 1993, public December 1994.
  • The paper trail dates the design before the code: AdLib editor ideas are dated 1991-08-10 and February 1992, while the PC player's own notes start in December 1991 and its header format in March 1992 (source: s-chordian-player-editor-notes).
  • Converting SID tunes to FM is not free. He kept a candidate list of C64 tunes to move to AdLib/Sound Blaster; "only laxity's The Alibi and Star Dream were eventually transferred among these" (source: s-chordian-player-editor-notes). His paid AdLib work came through the PC version of Hugo and the 1992 Harald Hårdtand, where drax composed on the C64 and JCH converted (source: s-chordian-my-computer-chronicles).

Pitch slides and tone portamento › Generic trackers #

Tone portamento is usually 3xx (slide the running note towards the new note at speed xx); pitch slides up/down 1xx/2xx. In S3M/IT the letters are Gxx to the note, Exx down, Fxx up, Lxy portamento + volume slide; ProTracker has fine slides E1x/E2x, which Vivid uses to steer a two-channel flange (sources: s-tw074-intro-to-musical-theory, s-tw077-chip-off-the-block, s-tw059-tracking-hints). In impulse-tracker tone portamento is Gxx, where xx/16 is the semitone step per tick — 037-lab converts its slide values to Gxx assuming speed 6 and tempo = BPM (source: s-037-lab).

Legato leads with Gxx (necros, source: s-tw012-advanced-tracking-tips): tone portamento "switches from note to note without re-starting the sample", which suits leads whose sample evolves over time. GF0 is practically instant — use it for every jump of more than three semitones so the lead is not "pitch bended too slowly"; smaller values (G20, G06) for one- or two-step moves; and put a GF0 on the row after a slow slide "to make sure that it makes it all the way up to the next note, since some players tend to play Gxx/3xx effects too slowly". Dan Hartrell's sax run uses G90 on every note for a "wavey" pipe-and-reed sound (source: s-tw021-tracking-tips). The whole recipe — velocity, legato, late vibrato, echo, drop-off — is on lead-articulation.

Units and limits per format (sources: s-protracker-23d-help, s-ft2-manual, s-st3-manual, s-st3-tech-doc, s-openmpt-manual-effect-reference, s-openmpt-manual-song-properties): ProTracker 1xx/2xx add to the Amiga period every tick ("called as many times as the speed of the song") and cannot pass B-3 (period 113) or C-1 (856); 3xx slides to the note (300 continues), E1x/E2x slide once ("Great for creating chorus effects"), E3x glissando snaps portamento to semitones. FT2 keeps the numbers, adds X1x/X2x extra-fine (speed ÷ 4), the volume-column Mx, and a linear frequency table that makes "all pitch bends run in constant speed, independent of the current frequency" (Amiga table = period slides). ST3's Exx/Fxx use periods four times finer than the Amiga's (hence EEx/FEx "four times more accurate"), with Gxx portamento and S1x glissando. IT/OpenMPT: with linear slides one unit = 1/16 semitone (extra-fine 1/64), otherwise a period (3,546,895 ÷ Hz; 3,579,364 in XM) — so a slide value means a different interval at every pitch; "Compatible Gxx" keeps tone-portamento memory separate from Exx/Fxx as FT2 does. Quirks: regular slides are not supposed to move at speed 1 (fine slides are); FT2 wraps a note slid too low "around at some point" into a very high note; IT plays nothing for a tone portamento with no previous note; ST3 continues a slide from the last arpeggiated note (source: s-openmpt-manual-compatible-playback).

Pulse width modulation (PWM) › Sample-based trackers #

Fake it by switching between pulse samples of different widths every row or two (source: s-037-lab); (unverified) or use single-cycle pulse samples with an instrument that cycles them.

Randomization and probability (MayBe, RandomiZe) › Other trackers #

(unverified) SID-Wizard has no probability or swing commands; fake variation with alternating patterns in the orderlist.

Retrigger and resync › Other trackers #

(unverified) SID-Wizard has no retrig command — use a wave table that re-gates (wavetable-programming).

Reverb and compression (offline, in the sample editor) › Inside the tracker #

The channel echo of the 1990s scene is, in Airon's words, "a primitive version" of reverb — its early reflections (source: s-tw118-reverb-and-compression); see fake-echo for the copies-on-extra-channels method, instrument-envelopes for looping a reverb tail under a volume envelope, and stereo-panning for spreading the echoes of a reverb-treated sample.

Shuffle, swing and FunkTempo › PC trackers #

Necros in 1995 (source: s-tw012-advanced-tracking-tips): the Amiga funk "floating tempo" alternates speeds row by row — A08 on the even rows, A05 on the odd — so the off-beat rows arrive late; the resulting average speed is 1 ÷ ((1/8 + 1/5) ÷ 2), "a bit slower than A06", and the swing amount is coarse. His refinement: alternate fine tempos instead, T60/T90 or T70/T9A, the first about two thirds of the second for a medium swing (his "Realization 2"); experiment from there. Dan Hartrell swings a sax run with A05/A08 (source: s-tw021-tracking-tips).

Alternating Axx speed commands row by row (e.g. speed 7 / speed 5) is the classic method in ST3/IT — every format's speed command can do it (Fxx below 20 in MOD/XM, Axx in S3M/IT), and IT/MPTM also extend single rows by ticks with S6x (XM: the X6x hack) (source: s-openmpt-manual-effect-reference). openmpt's MPTM format replaces the trick with Tempo Swing: in Modern tempo mode a slider per row of the beat lengthens or shortens that row, globally or per pattern; the rows always add up to the tempo, the swing survives tempo changes, plugins get a steady clock and no tempo commands litter the patterns (source: s-openmpt-manual-song-properties). ProTracker's speed is either VBlank ticks or CIA BPM, and FT2's "BPM is correct at speed 06" (sources: s-protracker-23d-help, s-ft2-manual).

Stereo panning › PC trackers #

  • A pan position is a balance, not a switch. In FastTracker 2's P0–PF scale P3 is about 80 % left and 20 % right; only P0/PF are one-sided, and P0 + PF on two channels is mono (trixter, source: s-tw055-panning-debate). GBlues's proposal of a second "reflection" channel at 25 % volume on the opposite side is therefore redundant as physics — but it survives as a stereo fake-echo flavour, and his pseudo-stereo drum trick (one loop on two opposite channels at 50 %, accent a side with a volume slide) still works.
  • Impulse Tracker: pan in the volume column (0–64) or with Xxx (00–FF; volume-column value = Xxx ÷ 4, X80 = centre — Airon's chart, source: s-tw106-a-little-panning); the ` volume-column entry changes pan while keeping vibrato; panning default per instrument, panning swing for subtle per-note variation, panning envelopes for beat loops (instrument-envelopes). Zinc's rules: kick in the middle; make things wide by doubling channels equidistant from the target with slightly different samples, a small offset/delay, or two consecutive notes; extremes at 00/64; "track as if your speakers are side by side" and let listeners lower the separation (default 128) (source: s-tw075-it-percussion-tips).
  • Panbrello Yxy filled down a bass channel with a fast rate and shallow depth (YF7) reads as width rather than movement (Pinion, source: s-tw081-it-tip-of-the-week); Pulse's single-row template C-4 01 X30 | C-5 01 XC0 is the cheapest stereo doubling (same source).
  • Vivid: place the echoes of a reverb-treated sample at different pan positions so it sounds "a bit more realistic" (source: s-tw059-tracking-hints).
  • Necros's ST3-era placement (source: s-tw012-advanced-tracking-tips): prefer channel panning to instrument panning (instrument pans suit drums only; a melodic sample plays lead, echo and chord roles in different places); never double a part on both sides "for stereo" — it wastes channels and muddies non-GUS mixes. Drums near the centre and slightly apart — kick and snare S87, hi-hats and tambourines S8A, crashes middle; the lead at S86–S8A with its echo mirrored at the same distance (S86 → S8A/S8B) or hard on the lead's side (S81); layered chords spread out, a single chord pad centred, one pan per note of a multi-channel chord; S8x on every row makes a hi-hat travel round the head. Stereo width from one sample: the same chord at the same note on a left and a right channel with O01 on one of them, panned well apart (S82/S8D or the extremes) — sample-offset as a delay line.
  • Two 128-step scales: in ST3 S8x is the 16-step GUS hardware pan (S80 left, S88 middle, S8F right; played correctly only by ST3 3.2+ on a GUS), and Xxx a 128-step software pan for DMP/IPlay — X00 left, X40 middle, X80 right, XA4 DMP's SBPro surround — which ST3 saves but does not play (source: s-tw012-advanced-tracking-tips). IT's Xxx runs 00–FF with X80 = centre (source: s-tw106-a-little-panning): the same letter, two ranges — an X40 from a 1995 S3M is centre, in an IT file it is quarter-left. The hardware side of the same story: on a cheap Sound Blaster Pro clone ST3 gave claim "either mono or stereo with swapping (which drove me crazy)", which is why some 1995 users moved to FT2 (source: s-tw015-interview-claim).
  • Stereo samples instead of panning (Zinc, source: s-tw094-stereo-samples-in-impulse-tracker): a panned mono sample stays mono — "shallow and fake" at pan 32 — while a stereo sample gives each ear a different signal. In IT load the stereo file twice, once as LEFT and once as RIGHT (IT asks), set the two samples' default pans hard left and right, and play identical note columns on two adjacent channels; twice the size and channels, so reserve it for kicks, bass and short hits and keep strings mono-panned.
  • Zinc's magazine-derived mix rule: bass in the centre, drums near but "not always dead center", lighter parts such as strings and guitars wider; check the mix in mono (source: s-tw096-studio-tracking-tips). Over MIDI the equivalent is controller 0A — 00 left, 40 centre, 7F right (midi-in-trackers; source: s-tw098-impulse-tracker-midi).
  • Per format (sources: s-openmpt-manual-effect-reference, s-ft2-manual, s-st3-manual, s-protracker-23d-help): the Amiga has a fixed L-R-R-L layout and ProTracker's 8xx/E8x are "NOT USED" (MOD players ignore panning); FT2 pans per instrument — 8xx 00–FF or Px in the volume column, reset by the next instrument number, with Pxy/Rx/Lx slides, and the GUS knows only 16 positions; ST3's S8x (0–F) is new in 3.2 and "only works on a GUS", with default pans per channel on F1; IT/OpenMPT pan per channel with Xxx 00–FF (pxx 0–64 in the volume column), Pxy slides, Yxy panbrello and S91 surround. FT2 used a square-root pan law that emphasises the centre — OpenMPT's "Compatible (FT2 Pan Law)" (source: s-openmpt-manual-song-properties). Changing NR51-style hard pans on a chip and instrument-based pans in XM are the two places a pan command silently resets.

Vibrato and delayed vibrato › Generic trackers #

Most trackers have a vibrato command, often 4xy (x = speed, y = depth): place it a few rows after the note starts, or use an instrument envelope with a delay (source: s-037-lab). In impulse-tracker / S3M the command is Hxy (4xy in protracker) and Kxy combines it with a volume slide; the Modsquad's chip lead uses H81/HA4 and puts an HFF vibrato on percussion instead of an arpeggio (sources: s-tw074-intro-to-musical-theory, s-tw077-chip-off-the-block).

Necros's rule for leads (source: s-tw012-advanced-tracking-tips): "Realistic vibrato, in a medium-tempo lead, starts out very soft and gradually fades in" — HA1 a row or two into a held note, then HA2, speeds 1–2 so the vibrato "doesn't become the main focus"; only "very up-tempo hard-hitting tunes" tolerate wild vibrato; and on a long sustain either bring it back to zero or fade the note, because "nothing sounds worse than a heavily oscillating note which just refuses to die" (lead-articulation). Over MIDI the modulation wheel (controller 01) usually sets vibrato depth only, the synth decides the rate (midi-in-trackers; source: s-tw098-impulse-tracker-midi).

Numbers from the manuals (sources: s-protracker-23d-help, s-ft2-manual, s-st3-manual, s-openmpt-manual-effect-reference, s-openmpt-manual-samples): ProTracker 4xy (400 continues; ProTracker 1.1A doubled the depth scale "to be compatible with NT2.0"), waveform E4x 0 sine, 1 ramp down, 2 square, 3 random, +4 = do not retrigger the waveform on a new note; FT2 the same plus a volume-column Vx and Sx (speed only); ST3 Hxy with Uxy four times finer "if a note is played very high", waveform S3x; IT/OpenMPT the same letters. Every LFO waveform is 64 points long and the speed is points per tick, so speed 2 completes a cycle in 32 ticks; "random" is unsupported by ProTracker and FastTracker. Sample-level auto-vibrato exists in XM (per instrument) and IT/MPTM (per sample): waveform, depth in 1/64 semitones, a sweep-in (IT: depth × 256 ÷ sweep ticks; XM: sweep ticks) and a rate of 256 ÷ rate ticks per cycle — it adds to pattern vibrato and cannot be changed from the pattern. FT2's ramp-down tremolo is a known bug ("even influenced by vibrato") (source: s-openmpt-manual-compatible-playback).