Ears

Mutable Instruments 4HP
I/O ENVELOPE UTILITY GATE

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Contact microphone with preamp, envelope follower, and gate detector. Mutable's take on Tom Whitwell's open-source Mikrophonie design. Turns physical touches, taps, and external audio into modular CV and gates.

Patch Ideas · 6

★ Percussive envelope from taps
Fast-attack/fast-release envelope jumper · GAIN at noon · tap the piezo pad · ENV → filter cutoff (attenuverter-scaled) · GATE → percussive envelope trigger on a VCA · taps on Ears become plucked notes with dynamic filter sweep.
▸ Show diagram
Patch diagramPatch diagram with 6 modules and 4 connections. Modules: Ears, VCO, Filter, Envelope, VCA, Filter (In) -> VCA (In) -> Output. Signals: 1 audio, 2 cv, 1 gate.EarsVCOFilterEnvelopeVCAFilter (In) -> VCA (In) -> OutputEnvelope jumper: fastGate jumper: mediumGAIN: noonENVcvGATEgateOutaudioCutoffcvTriggateOutcvCVcvInaudioaudiocvgate
Voice-controlled vocoder-style filter
External microphone (or spoken voice picked up by piezo) · slow envelope jumper · GAIN high for sensitivity · ENV → VCF cutoff with attenuverter at 2 o'clock · drone VCO into the filter · voice dynamics open the filter, producing a crude wah/vocoder effect without any digital processing.
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 3 connections. Modules: Ears, VCO, Filter, Microphone, Filter (In) -> Output. Signals: 2 audio, 1 cv.EarsVCOFilterMicrophoneFilter (In) -> OutputEnvelope jumper: slowGAIN: ~3 o'clockINaudioENVcvDroneaudioCutoffcvOutaudioInaudioaudiocv
★ Acoustic clock source
Metronome, kick drum, or clapping hands near the piezo · medium gate threshold · GATE → clock input of a sequencer · Ears converts acoustic rhythm into modular clocks so a live drummer or a metronome app can clock a patch without a MIDI interface.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Ears, Sequencer, VCO, Envelope. Signals: 1 pitch, 1 gate, 1 clock.EarsSequencerVCOEnvelopeGate jumper: mediumGATEclkClockclkPitch1v/octGategateV/Oct1v/octTriggatepitchgateclock
★ Guitar into modular
Electric guitar → IN (disconnects piezo) · GAIN at 3 o'clock to hit modular level · OUT → wavefolder → filter → VCA · ENV → wavefolder amount so playing harder pushes into folding · GATE → envelope trigger for note-on dynamics.
▸ Show diagram
Patch diagramPatch diagram with 7 modules and 5 connections. Signals: 2 audio, 2 cv, 1 gate.EarsGuitarWavefolderFilterEnvelopeVCAWavefolder (In) -> Filter (In) -> VCA (In) -> OutputGAIN: ~3 o'clockINaudioOUTaudioENVcvGATEgateOutaudioFold CVcvTriggateOutcvCVcvInaudioaudiocvgate
Speaker-feedback resonator
Patch a VCO through a high-Q filter into a nearby monitor speaker · speaker vibration couples through case into Ears' piezo · Ears (OUT) → filter FM input · closes an acoustic feedback loop · GAIN knob controls the onset of howl · tapping the case modulates the resonance.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: Ears, VCO, Filter, Monitor. Signals: 3 audio, 1 cv.EarsVCOFilterMonitorPiezoaudioOUTcvOutaudioInaudioFM CVcvOutaudioInaudioAcousticaudio121. physical speaker near Ears2. acoustic feedback loopaudiocv
Dual-path envelope and audio
Contact-mic scrape → OUT → granular processor for audio texture · same signal's ENV → granular density CV · GATE → trigger freeze on the granular · single physical gesture drives audio, texture density, and freeze behaviour simultaneously.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 4 connections. Modules: Ears, Granular, Output. Signals: 2 audio, 1 cv, 1 gate.EarsGranularOutputEnvelope jumper: mediumGate jumper: highOUTaudioENVcvGATEgateInaudioDensity CVcvFreezegateOutaudioInaudioaudiocvgate

Behaviors

Contact mic normalization IN unpatched

The piezo contact pad on the panel is normalled into the preamp. Patching any cable into IN disconnects the piezo — useful for using Ears as a clean Hi-Z amp for guitar, bass, or line-level sources without mic crosstalk.

Envelope follower time jumpers rear jumper position

Three discrete attack/release presets. Fastest tracks individual transients for percussive triggering; slowest smooths to a pad-like CV. Removing the jumper entirely selects the longest setting — there is no front-panel access, so set once for the session.

Gate threshold jumpers rear jumper position

Three gate-detector thresholds. Lowest fires on subtle taps or ambient noise (good for self-triggering). Highest ignores all but hard hits. Removing the jumper gives the highest threshold, useful as a noise gate for loud external signals.

Envelope + audio simultaneity GAIN turned up with audio applied

OUT carries the clean amplified audio while ENV and GATE run in parallel. A single guitar or drum can drive a VCF cutoff (ENV) while being processed as audio (OUT) and triggering an envelope (GATE) at the same time — Ears acts as a three-way gateway from the acoustic world.

Speaker-feedback chain monitor/speaker bleeding into the piezo

With nothing patched to IN, a monitor or speaker near the Ears panel couples vibration into the piezo. Feeding modular output back into monitors creates a physical acoustic feedback loop controllable via GAIN — Mutable explicitly advertises speaker feedback as a use case.

Gate from non-percussive audio sustained signal + low threshold jumper

When gate threshold is set to the lowest jumper setting and envelope follower to a slow release, sustained pads or bowed sources produce a hold-high gate that only drops when the source goes silent. Effectively turns Ears into a voice-activated gate for patch routing.

No S/H or auto-gain reading the panel

Despite rumours, Ears has no sample-and-hold mode and no automatic gain control — GAIN is manual, and the envelope/gate path is analog. All adaptive behaviour lives in the jumper presets at the rear of the PCB.

Controls

Global GAIN Preamp gain for contact mic or Hi-Z input. Covers line-level boost to tiny contact-mic transients.
0 to +40dB · CW = more gain · clipping lit by red LED at OUT
Panel-mounted sensor Contact microphone (piezo disc) Large piezo pad on the front panel. Scratch, tap, rub, brush, or press objects against it for acoustic excitation sources.
Hi-Z jack overrides the mic when a cable is inserted
Rear of PCB Envelope follower jumpers Three-position jumper for envelope follower attack/release. Third setting (jumper removed) is the longest time.
3 presets: fast · medium · slow (no jumper = longest)
Rear of PCB Gate detector jumpers Three-position jumper for the gate threshold. Third setting (jumper removed) is the highest threshold voltage.
3 presets: low · medium · high (no jumper = highest)

I/O

IN · 1

  • IN line-level to instrument-level · Hi-Z AUDIO
    Hi-Z audio input. Patching here disconnects the contact microphone and routes the external source through the same preamp.

OUT · 3

  • OUT modular level (~±5V clean before clip) AUDIO
    Amplified audio output of the contact mic or external IN. Red LED lights on clipping.
  • ENV ~0 to +5V · attack/release set by rear jumpers ENV
    Envelope follower CV. Tracks the amplitude of the amplified signal. White LED shows CV level.
  • GATE +8V gate · threshold jumper-selectable GATE
    Gate output. Goes high whenever the envelope crosses the threshold set by the rear gate-detector jumpers. Orange LED mirrors activity.