Basimilus Iteritas Alter

Noise Engineering 10HP
DRUM OSCILLATOR WAVEFOLDER VCO

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Parameterized digital drum synthesizer. Six tonal plus one noise oscillator summed through an infinifolder with amplitude-compensated envelope. Three modes: Skin, Liquid, Metal. Full CV on every parameter and switch.

Patch Ideas · 10

★ Classic 909 kick
Mode: Liquid · B/A/T: Bass · Pitch 9 o'clock · Decay 2 o'clock · Attack noon · Morph 10 o'clock (tri-ish) · Harm 10 o'clock · Fold 10 o'clock · Spread full CCW · clock triggers Trig · Liquid pitch envelope delivers the 909 bloom without external envelope · tighten by lowering Decay
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: Basimilus Iteritas Alter, Clock, Mixer. Signals: 1 audio, 1 trigger.Basimilus Iteritas AlterClockMixerMode: Liquid · Range: BassPitch: 9 o'clock · Decay: 2 o'clock · Harm: 10 o'clock · Morph: 10 o'clock · Fold: 10 o'clock · Spread: full CCWTrigtrigOutaudioOuttrigInaudioaudiotrigger
Metal crash with morphing ratio
Mode: Metal · B/A/T: Treble · Pitch noon · Decay 3 o'clock · Attack noon · slow triangle LFO → Spread CV (±2V) · stepped random → Harm CV · every hit lands on a different FM ratio with different decay structure · gate sequencer fires Trig · ghost hi-hats and wash crashes out of one module
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 4 connections. Modules: Basimilus Iteritas Alter, LFO, S&H, Gate Seq, Mixer. Signals: 1 audio, 2 cv, 1 trigger.Basimilus Iteritas AlterLFOS&HGate SeqMixerMode: Metal · Range: TreblePitch: noon · Decay: 3 o'clock · Attack: noonSpreadcvHarmcvTrigtrigOutaudioTricvOutcvOuttrigInaudioaudiocvtrigger
Pulse-train snare
Mode: Skin · B/A/T: Alto · Pitch 10 o'clock · Decay 10 o'clock · Attack 9 o'clock (noise blend) · Morph 3 o'clock · Harm 1 o'clock · Fold full CW (pulse injection) · Spread noon · noise attack plus pulse-buzz folder yields a gritty 606-style snare · envelope out of Maths → Attack CV for velocity-sensitive noise blend
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: Basimilus Iteritas Alter, Clock, CH 1, Mixer. Signals: 1 audio, 1 cv, 2 trigger.Basimilus Iteritas AlterClockCH 1MixerMode: Skin · Range: AltoPitch: 10 o'clock · Decay: 10 o'clock · Attack: 9 o'clock · Harm: 1 o'clock · Fold: full CW · Spread: noon · Morph: 3 o'clockenvelopeTrigtrigAttackcvOutaudioOuttrigTrigtrigOUTcvInaudioaudiocvtrigger
Mode-jumping drum voice
Stepped random (0–5V) → S/L/M CV · each trigger lands on Skin, Liquid, or Metal randomly · Pitch noon · Decay 1 o'clock · Attack 11 o'clock · Harm 11 o'clock · Fold noon · Spread 1 o'clock · same parameter settings sound dramatically different per mode — single-voice drum kit from a stepped random source
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: Basimilus Iteritas Alter, S&H, Clock, Mixer. Signals: 1 audio, 1 cv, 2 trigger.Basimilus Iteritas AlterS&HClockMixerPitch: noon · Decay: 1 o'clock · Attack: 11 o'clock · Harm: 11 o'clock · Fold: noon · Spread: 1 o'clockS/L/McvTrigtrigOutaudioTrigtrigOutcvOuttrigInaudioaudiocvtrigger
★ Pitched melodic voice
Mode: Skin · B/A/T: Alto · quantized sequencer → Pitch 1V/oct · Decay full CW (drone) · Attack 1 o'clock (slow) · Harm 11 o'clock · Fold 10 o'clock · Morph 9 o'clock (sine-ish) · Spread full CCW (strict harmonic) · held trigger (or loop gate) · plays as a 6-partial additive synth voice for melodic material
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Basimilus Iteritas Alter, Sequencer, Gate Source, Mixer. Signals: 1 audio, 1 pitch, 1 gate.Basimilus Iteritas AlterSequencerGate SourceMixerMode: Skin · Range: AltoDecay: full CW · Attack: 1 o'clock · Harm: 11 o'clock · Fold: 10 o'clock · Morph: 9 o'clock · Spread: full CCWPitch1v/octTriggateOutaudioPitch1v/octOutgateInaudio11. sustained gateaudiopitchgate
Octave-stepping tom fill
Mode: Liquid · ascending 3-step CV (0V, 2.5V, 5V) → B/A/T CV · same trigger fires BIA · three identical hits jump Bass → Alto → Treble · Pitch 11 o'clock · Decay 1 o'clock · Harm noon · produces a classic ascending tom fill from a single-voice · Maths can easily generate the ramp via CH 1 Rise
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: Basimilus Iteritas Alter, Clock, CH 1, Mixer. Signals: 1 audio, 1 cv, 2 trigger.Basimilus Iteritas AlterClockCH 1MixerMode: LiquidPitch: 11 o'clock · Decay: 1 o'clock · Harm: noonramp 0-5VB/A/TcvTrigtrigOutaudioOuttrigTrigtrigOUTcvInaudio11. ascending octavesaudiocvtrigger
Noise-attack hi-hat
Mode: Metal · B/A/T: Treble · Pitch 2 o'clock · Decay 9 o'clock (short) · Attack full CCW (max noise) · Harm 3 o'clock (many harmonics) · Fold 2 o'clock · Spread 1 o'clock · euclidean gate → Trig · short decay plus noise attack gives crisp digital hi-hat · CV Decay for open/closed variation
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Basimilus Iteritas Alter, Euclidean, Gate Seq, Mixer. Signals: 1 audio, 1 cv, 1 trigger.Basimilus Iteritas AlterEuclideanGate SeqMixerMode: Metal · Range: TreblePitch: 2 o'clock · Decay: 9 o'clock · Attack: full CCW · Harm: 3 o'clock · Fold: 2 o'clock · Spread: 1 o'clockTrigtrigDecaycvOutaudioOuttrigOutcvInaudio11. open/closed HHaudiocvtrigger
★ FM bass with morph sweep
Mode: Metal · B/A/T: Bass · Pitch 8 o'clock · Decay full CW · Attack noon · Harm 11 o'clock · Fold 9 o'clock · slow sine LFO → Morph CV (full swing) · sustained gate into Trig · pitched 1V/oct sequencer · drone-bass voice with a slowly morphing FM character · works as a reese-style bass for techno
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 5 connections. Modules: Basimilus Iteritas Alter, Sequencer, LFO, VCF, Mixer. Signals: 2 audio, 1 cv, 1 pitch, 1 gate.Basimilus Iteritas AlterSequencerLFOVCFMixerMode: Metal · Range: BassDecay: full CW · Attack: noon · Harm: 11 o'clock · Fold: 9 o'clockPitch1v/octTriggateMorphcvOutaudioPitch1v/octGategateSinecvInaudioOutaudioInaudio121. sustain2. slow full-swing sweepaudiocvpitchgate
Velocity-scaled kick via envelope-mod-Fold
Mode: Liquid · Pitch 9 o'clock · Decay 1 o'clock · Attack noon · Harm 10 o'clock · Spread full CCW · envelope follower on external hat track → Fold CV · kick intensity follows other drum energy · ducking-like buzz response that swells into syncopated density · trigger fires on downbeats only
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 4 connections. Modules: Basimilus Iteritas Alter, Clock, Env Follower, Hat Bus, Mixer. Signals: 2 audio, 1 cv, 1 trigger.Basimilus Iteritas AlterClockEnv FollowerHat BusMixerMode: LiquidPitch: 9 o'clock · Decay: 1 o'clock · Attack: noon · Harm: 10 o'clock · Spread: full CCWFoldcvTrigtrigOutaudioOuttrigInaudioEnvcvOutaudioInaudio11. buzz follows hat energyaudiocvtrigger
Self-triggered aliasing bell
Mode: Metal · B/A/T: Treble · Pitch 3 o'clock (high) · Decay 2 o'clock · Attack noon · Harm full CW · Fold full CW · Spread 2 o'clock (between-positions — max aliasing) · audio-rate trigger from square VCO (~50 Hz) into Trig · digital bell voice with gritty re-triggered FM character · pitch the VCO for metallic bell sequences
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Basimilus Iteritas Alter, VCO, LFO, Mixer. Signals: 1 audio, 1 pitch, 1 trigger.Basimilus Iteritas AlterVCOLFOMixerMode: Metal · Range: TreblePitch: 3 o'clock · Decay: 2 o'clock · Harm: full CW · Fold: full CW · Spread: 2 o'clockWave: Square · ~50 HzTrigtrigOutaudioV/Oct1v/octOuttrigOut1v/octInaudio121. audio-rate re-trigger2. bell sequenceaudiopitchtrigger

Behaviors

Skin mode S/L/M switch → Skin (or 0V at S/L/M jack)

Six-operator additive synth. Each oscillator plays a static partial determined by Spread. Skin models non-interacting drum modes — classic kicks, toms, metallic stabs. Fold and Harm are the main timbre sculptors here since there is no pitch envelope.

Liquid mode S/L/M switch → Liquid (or mid CV at S/L/M jack)

Skin architecture with an added pitch envelope on all six oscillators. Produces the punchy pitch drop of classic kicks without external patching. Decay knob affects both amplitude and pitch envelope length. Best mode for 808/909-style kicks.

Metal mode S/L/M switch → Metal (or high CV at S/L/M jack)

Classic 80s-style FM: the six oscillators phase-modulate each other with no regard for aliasing. Produces bell, cowbell, metallic crash, and alien noise textures. Spread and Harm become frequency-ratio controls; small changes cause huge timbral shifts.

CV overrides mode switch cable → S/L/M or B/A/T CV input

Both mode/octave switches are CV-scannable. Patching gate or LFO to S/L/M flips between Skin/Liquid/Metal per-hit. B/A/T CV enables stepped octave jumps. Both jacks accept 0–5V and override the physical switch when patched.

Infinifold with pulse injection Fold knob in top quarter

Below 75%, Fold threshold is set and the internal engine dynamically stacks fold stages to maximize folding while compensating amplitude. Past 75% an exponentially-decaying pulse is injected at signal minima/maxima, adding a gnarly buzz that tracks pitch. Key sound-design zone for noisy snares and sub-bass.

Post-fold envelope restore any trigger

After the folder, BIA re-applies an envelope derived from the summed oscillator shape. This restores the punchy dynamic that folding normally kills, so even maximum Fold keeps percussive umph instead of becoming a steady-state tone.

Inharmonic Spread Spread knob CW

Spread at CCW or fully CW produces strictly harmonic series; intermediate positions interpolate toward the prime-number series. Combined with aligned-alias sample rate, CCW and CW give the cleanest tonal results; between-positions add unique aliasing character.

Variable sample rate aliasing any pitch

Internal sample rate is a multiple of the fundamental. Aliases fall on harmonics of the fundamental when Spread is fully CCW or CW — this makes aliasing musically aligned rather than noisy. Between Spread positions, aliasing adds unique digital character to the sound.

Pitched drone oscillator Decay fully CW + sustained trigger

With Decay maxed and Trig held high (or looped sub-audio trigger), BIA sustains indefinitely as a pitched drone voice. Morph, Harm, Spread become timbre controls for a pseudo-additive oscillator. Pitch input tracks 1V/oct across the useful range for melodic use.

5V rail option rear PCB switch

Rear-panel tab switch routes the processor to the 5V eurorack rail instead of 12V. Reduces 12V noise and current load (drops +12V from 150mA to 80mA). Requires a case that supplies the 5V rail.

Controls

Global Pitch Fundamental oscillator pitch. Knob sums with CV input.
1V/oct · sums with Pitch CV
Global Morph Blends the waveform of all oscillators continuously through sine → triangle → saw → square. Knob offsets the CV input.
CCW: sine · noon: saw · CW: square
Global Attack Shapes attack for all oscillators and noise. CCW adds noise; dead center is classic analog pop; CW slows attack. Knob offsets CV.
CCW: noise · noon: click · CW: slow attack
Global Decay Decay time for all oscillators. Knob offsets the CV input.
short to long · CV offset
Global Harmonic Harmonic decay/amplitude of the six oscillators. CCW: single tone. First quarter fades in a second harmonic. Remaining range extends decay then amplitude of harmonics 3–6.
CCW: 1 partial · CW: 6 partials with long decays
Global Fold Infinifolder threshold. Dynamically adds fold stages based on amplitude. Top quarter mixes in a signal-following pulse train for gnarly buzz.
0–75%: threshold fold · 75%+: pulse-train buzz
Global Spread Frequency spacing of the five non-fundamental oscillators. Sweeps from harmonic series to prime/inharmonic series.
CCW: harmonic · CW: inharmonic (prime)
Global S/L/M Switch Mode selector. Skin: 6-op additive. Liquid: additive plus pitch envelope on all oscillators. Metal: 6-op FM with cross-modulation between oscillators.
Skin · Liquid · Metal · CV-overridable via S/L/M jack
Global B/A/T Switch Octave range offset. Alto is +2 octaves; Treble is +4 octaves relative to Bass.
Bass · Alto (+2 oct) · Treble (+4 oct) · CV-overridable via B/A/T jack
Global HIT Momentary manual trigger button. Sums with Trig input — useful for live hits without patching a cable.
momentary

I/O

IN · 10

  • Pitch 1V/oct CV
    1V/oct pitch CV for the fundamental oscillator. Sums with Pitch knob.
  • Morph 0–5V CV
    CV for waveshape. Sums with Morph knob offset.
  • Attack 0–5V CV
    CV for attack parameter. Sums with Attack knob offset.
  • Decay 0–5V CV
    CV for decay parameter. Sums with Decay knob offset.
  • Harm 0–5V CV
    CV for harmonic parameter. Sums with Harmonic knob offset.
  • Fold 0–5V GATE
    CV for fold threshold and pulse-train mix. Sums with Fold knob offset.
  • Spread 0–5V CV
    CV for frequency spacing of harmonics. Sums with Spread knob offset.
  • S/L/M 0–5V CV
    CV overrides the Skin/Liquid/Metal switch. Voltage scans across the three modes.
  • B/A/T 0–5V CV
    CV overrides the Bass/Alto/Treble octave switch. Voltage selects range.
  • Trig ~3V threshold GATE
    Rising-edge trigger fires the drum envelope. Retrigger ignored while envelope is rising.

OUT · 1

  • Out audio AUDIO
    Main audio output. Low-impedance. Level varies with parameters — internal loudness compensation applied after the folder.