Ikarie

Bastl Instruments 8HP
FILTER VCF VCA ENVELOPE

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Stereo twin-core 12dB/oct state-variable filter with continuous LP↔HP cutoff, envelope follower, stereo VCA, and BEYOND difference output. Designed by Casper Electronics × Bastl.

Patch Ideas · 6

Auto-wah guitar in
leave MOD unpatched · FOLLOW switch MID · INPUT high · send guitar or drum loop through L IN · filter tracks envelope automatically · adjust MOD knob for depth and direction
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 3 connections. Modules: Ikarie, External, Output. Signals: 3 audio.IkarieExternalOutputFOLLOW: MIDINPUT: 4 o'clockMOD: 1 o'clockCUTOFF: noonL INaudioL OUTaudioR OUTaudioOutaudioLaudioRaudioaudio
Formant vocal filter
mono signal to L IN · STEREO switch SPREAD · STEREO knob ~2 o'clock · RESONANCE high · listen L OUT only · sweeping CUTOFF yields throaty formant sweep
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Ikarie, VCO, LFO, Output. Signals: 2 audio, 1 cv.IkarieVCOLFOOutputSTEREO switch: SPREADSTEREO: ~2 o'clockRESONANCE: 75%L INaudioMODcvL OUTaudioSawaudioOutcvInaudioaudiocv
★ Twin peak stereo drone
noise into L IN · STEREO SPREAD wide · L OUT to left · BEYOND to right · creates disorienting stereo image with sum on one side, difference on the other
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: Ikarie, Noise, LFO, Output. Signals: 3 audio, 1 cv.IkarieNoiseLFOOutputSTEREO switch: SPREADSTEREO: fullRESONANCE: 80%L INaudioMODcvL OUTaudioBEYONDaudioOutaudioOutcvLaudioRaudioaudiocv
★ Pinged snare
trigger burst to L IN · INPUT 3 o'clock · RESONANCE max · FOLLOW fast · FOLLOW → VCA CV · BEYOND gives metallic ring · self-contained percussion voice
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 3 connections. Modules: Ikarie, Clock, Output. Signals: 1 audio, 1 cv, 1 trigger.IkarieClockOutputRESONANCE: maxFOLLOW: FASTSTEREO switch: SPREADSTEREO: ~1 o'clockL INtrigVCA CVcvFOLLOWcvBEYONDaudioOuttrigInaudio11. trigger as audioaudiocvtrigger
★ Serial 24dB acid bass
L OUT into R IN · listen R OUT · RESONANCE high · envelope to MOD · INPUT drive for overdrive · steep saturated bass with classic 24dB character
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: Ikarie, VCO, Envelope, Output. Signals: 3 audio, 1 cv.IkarieVCOEnvelopeOutputINPUT: 4 o'clockRESONANCE: 70%L INaudioR INaudioMODcvL OUTaudioR OUTaudioSawaudioOutcvInaudio11. seriesaudiocv
Stereo VCA gate
stereo pair from external to L IN / R IN · envelope to VCA CV only · CUTOFF open · use Ikarie as stereo VCA with optional filter coloring
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 5 connections. Modules: Ikarie, Envelope, External, Output. Signals: 4 audio, 1 cv.IkarieEnvelopeExternalOutputCUTOFF: noon (open)RESONANCE: 0L INaudioR INaudioVCA CVcvL OUTaudioR OUTaudioOutcvLaudioRaudioLaudioRaudioaudiocv

Behaviors

Continuous LP↔HP morphing turn CUTOFF across range

CCW half sweeps a low-pass from closed to open; CW half sweeps a high-pass from open to closed. A single knob morphs between filter types without a mode switch — great for unified tonal gestures.

Built-in auto-wah leave MOD input unpatched

FOLLOW output is internally normalled to MOD input. Any signal at INPUT modulates its own cutoff — classic envelope-follower filter effect with no external envelope needed. FOLLOW switch chooses response time.

Twin peak filter (BEYOND) use BEYOND output with STEREO in SPREAD

BEYOND takes the difference of L and R filter outputs — when cutoffs are detuned via SPREAD, yields a band-pass sitting between the two peaks. Add resonance for dual-formant vocal timbres.

Mono dual-peak formant use L OUT only with STEREO in SPREAD

L OUT sums both filter outputs. With STEREO spreading cutoff, creates two simultaneous resonant peaks — formant filtering from a mono signal with no external routing.

Series 24dB filtering patch L OUT → R IN, listen to R OUT

Chains the two 12dB filter cores in series for a 24dB/oct steep response. Stereo behavior is lost, but cutoff attenuation doubles. Add INPUT gain or SPREAD for aggressive serial distortion.

Pinged percussion trigger/noise burst to L IN, RESONANCE high

High resonance plus a transient at INPUT excites the filter as a percussive voice. Use BEYOND or MOD in SPREAD for metallic tones. FOLLOW → VCA CV gates the burst's decay automatically.

Audio-rate stereo ring mod audio at STEREO input, PAN mode, listen BEYOND

In PAN mode, the STEREO knob crossfades between L and R filter outputs. Modulating at audio rate with STEREO jack patched and listening on BEYOND yields ring-modulated tones — the difference cancels the shared spectrum.

External feedback patch L OUT or R OUT back into L IN or R IN

Creates exaggerated resonance / feedback beyond internal RESONANCE range. INPUT knob caps the gain — careful scaling produces chaotic pinged drones or unstable tones.

VCA normally silent leave VCA CV unpatched

The output stereo VCA defaults to open (normal filter level) when VCA CV has nothing plugged in. Patching 0V there mutes output — use positive CV (env, LFO) to sculpt amplitude without external VCA.

Controls

Global CUTOFF Large knob sweeps continuously from LP (CCW) through open (noon) to HP (CW). Controls both filter cores in sync.
LP ↔ open ↔ HP · 20Hz – 20kHz
Global RESONANCE Fader for filter Q. Self-oscillates as sine at max with no input. Becomes attenuator for RESONANCE CV when cable inserted.
Fader · self-osc at max · voltage-controlled
Global MOD Attenuverter for the MOD CV input feeding both filters' cutoff in tandem. Normalled from FOLLOW output when MOD unpatched.
CCW: invert · noon: zero · CW: unity
Global STEREO Controls stereo behavior per switch setting: detunes left/right cutoff (SPREAD) or pans between left/right filter levels (PAN). Becomes attenuator when STEREO jack patched.
Bipolar · SPREAD or PAN mode
Global STEREO switch Selects PAN (balance L/R VCA levels) or SPREAD (detune L/R cutoff frequencies).
PAN · SPREAD
Global INPUT Pre-filter gain from 0x to 5x. Drives the filter to overdrive at high settings; also sets amplitude feeding the FOLLOW envelope.
0x – 5x · unity mid
Global FOLLOW switch Envelope follower response speed — SLOW (natural release, pumping), MID (tight, balanced), FAST (near full-wave rectifier, per-cycle modulation).
SLOW · MID · FAST

I/O

IN · 7

  • L IN line level · amplified by INPUT AUDIO
    Left filter input. Normalled to R IN for dual-mono operation.
  • R IN line level AUDIO
    Right filter input. Accepts independent signal; otherwise sees L IN via normalling.
    NORM → L IN
  • V/OCT 1V/Oct CV
    Second modulation input added to cutoff. 1V = one octave shift (calibratable via front-panel trimmer).
  • MOD CV
    Main cutoff modulation input, attenuverted by MOD knob. Normalled from FOLLOW output for built-in auto-wah.
    NORM → FOLLOW output
  • STEREO CV
    CV for the stereo parameter (spread or pan). Converts STEREO knob into an attenuator when patched.
  • RESONANCE CV
    CV for resonance. Turns RESONANCE fader into a cap on the modulation range when patched.
  • VCA CV 0V – 5V · unity at 5V CV
    Positive CV opens both output VCAs simultaneously. Silent with no CV patched.

OUT · 4

  • L OUT (MONO) AC-coupled
    Left filter output. Sums L + R when R OUT is unpatched — use alone for mono.
  • R OUT
    Right filter output. Splits the stereo image when patched (disables the mono sum on L OUT).
  • BEYOND
    Difference spectrum between the two filters — a band-pass between left and right cutoff frequencies (twin peak filter).
  • FOLLOW ENV
    Envelope follower CV tracking INPUT signal loudness. Response set by FOLLOW switch. Normalled to MOD input.