3x MIA

Happy Nerding 6HP
MIXER ATTENUVERTER UTILITY

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Three independent 2-channel attenuverting mixers using concentric pots. DC-coupled for audio or CV. Chain switches reconfigure as 2-2-2, 4-2, or 6-into-1. Offsets normalized when inputs unpatched.

Patch Ideas · 6

★ Six-LFO complex modulator
Six LFOs summed through all three blocks into Out 3 as one evolving CV.
Walkthrough
  1. Flip both chain switches down (6-into-1 configuration — all blocks sum into Out 3).
  2. Patch six different LFO outputs (ideally varied rates: slow, medium, fast) → A 1, B 1, A 2, B 2, A 3, B 3.
  3. Start with every knob at center (silent) so you hear nothing at first.
  4. Patch 3x MIA (Out 3) → filter cutoff (or any destination needing complex CV).
  5. Dial each knob CW or CCW one at a time to add each LFO into the sum — CW adds it straight, CCW adds it inverted.
  6. Balance the six contributions by ear; back off any LFO that dominates.
Signal out Out 3 — the sum of all six LFOs, each scaled and optionally inverted by its knob.
Listen for A slow, endlessly evolving CV that never quite repeats because six different rates are interfering. Great for filter cutoff, wavetable position, or FM index. If motion feels flat, invert one or two LFOs (turn those knobs CCW) to break the sync.
▸ Show diagram
Patch diagramPatch diagram with 8 modules and 7 connections. Signals: 7 cv.3x MIALFO 1LFO 2LFO 3LFO 4LFO 5LFO 6FilterChain switches: both down (6-into-1)A 1cvB 1cvA 2cvB 2cvA 3cvB 3cvOut 3cvOutcvOutcvOutcvOutcvOutcvOutcvCutoffcvcv
★ Stereo panner from one source
Mono source multed to A1 (CW) and B1 (CCW) for a dry/inverted pair routed L and R.
Walkthrough
  1. Keep both chain switches up (2-2-2 — block 1 stays independent).
  2. Mult a mono source. Send copy 1 → A 1. Send copy 2 → B 1.
  3. Turn A 1 knob fully clockwise (signal passes straight through at unity).
  4. Turn B 1 knob fully counter-clockwise (signal is inverted at unity).
  5. Patch 3x MIA (Out 1) → stereo L.
  6. For the R side, move one of the copies to block 2 instead (e.g. A 2 full CW) and patch Out 2 → stereo R. Flip A 2 to CCW if you want the inverted mirror on the right.
Signal out Out 1 — the sum A 1 + B 1. With A CW and B CCW the sum near-cancels; use Out 2 as the out-of-phase partner for width.
Listen for Haas-style fake stereo width from a mono source. Not a true pan law, but useful for thickening a single VCO. Start B 1 near center and creep CCW — the sense of width grows as the two signals diverge in polarity.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 5 connections. Modules: 3x MIA, Mono Source, Mult, Output. Signals: 5 audio.3x MIAMono SourceMultOutputA1: full CW · B1: full CCW (invert)A 1audioB 1audioOut 1audioOut 2audioOutaudioInaudioOut 1audioOut 2audioLaudioRaudio11. use Out 2 as inverted mirroraudio
★ CV transpose with attenuated modulation
Sum sequencer pitch + manual octave offset + vibrato in blocks 1 and 2, chained to Out 2.
Walkthrough
  1. Flip chain switch 1 down (block 1 sums into block 2).
  2. Patch sequencer 1V/oct → A 1. Turn A 1 fully clockwise (unity — preserves tracking).
  3. Leave B 1 unpatched. Its knob is now a bipolar offset. Set B 1 to noon for no transpose; CW adds octaves up, CCW adds octaves down.
  4. Patch vibrato LFO (sine) → A 2. Keep A 2 near center and open it slowly for vibrato depth.
  5. Patch 3x MIA (Out 2) → VCO (1V/oct).
  6. Check tracking first (A 1 at CW, everything else centered). Then dial in transpose with B 1 and vibrato with A 2.
Signal out Out 2 — sum of (A 1 pitch + B 1 offset) chained in, plus A 2 vibrato and B 2 (unused unless you add glide CV).
Listen for Sequencer melody with a live transpose knob and a vibrato fader. B 1 acts like a coarse tune; nudge it a few ticks for perfect octave jumps (test by ear against the sequence). A 2 lets you swell vibrato in and out during a performance.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: 3x MIA, Sequencer, LFO, VCO. Signals: 1 cv, 2 pitch.3x MIASequencerLFOVCOChain 1: down · A1: full CW · B1: manual offset · A2: vibrato depthA 11v/octA 2cvOut 21v/octPitch1v/octSinecvV/Oct1v/octcvpitch
Polarity flipper for envelope
One envelope multed into A1 (inverted) and B1 (positive) feeds two destinations moving in opposite directions.
Walkthrough
  1. Keep chain switches up (block 1 independent; we'll use Out 1 and Out 2 separately).
  2. Mult one envelope into two copies.
  3. Copy 1 → A 1. Turn A 1 fully counter-clockwise (inverts the envelope).
  4. Copy 2 → A 2. Turn A 2 fully clockwise (passes the envelope straight).
  5. Patch 3x MIA (Out 1) → VCA CV — inverted envelope ducks the VCA when the original envelope fires.
  6. Patch 3x MIA (Out 2) → filter cutoff — positive envelope opens the filter on the same trigger.
  7. Back off either knob from the extremes if the response feels too extreme.
Signal out Out 1 — inverted envelope (for ducking). Out 2 — positive envelope (for swells).
Listen for One trigger makes the filter brighten while the VCA dips — instant ducking effect. Useful for kick-driven sidechain on a drone pad, or for classic 'open the filter but drop the level' brass stabs. Flip either knob past center to trim how much each side moves.
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 5 connections. Modules: 3x MIA, Envelope, Mult, VCA, Filter. Signals: 1 audio, 4 cv.3x MIAEnvelopeMultVCAFilterA1: full CCW (invert) · B1: full CWA 1cvB 1cvOut 1cvOut 2cvOutaudioInaudioOut 1cvOut 2cvCVcvCutoffcv121. inverted = ducking2. positive = swellaudiocv
Manual offset bank
All six inputs unpatched turns every knob into a bipolar manual offset; three separate Outs feed three destinations.
Walkthrough
  1. Leave every A and B input unpatched — each knob now rides the internal normalled offset voltage.
  2. Keep both chain switches up (2-2-2) so each Out stays independent.
  3. Knob center = 0 V. CW = positive offset, CCW = negative.
  4. Patch Out 1 → filter cutoff. Set A 1 + B 1 to taste for a bias voltage (they sum).
  5. Patch Out 2 → VCO 1V/oct. Tune A 2 and B 2 by ear to pick an octave/fifth offset.
  6. Patch Out 3 → comparator threshold (or any CV destination). Set A 3 + B 3 for the threshold level.
  7. Fine-tune while listening — there is no voltmeter, so trust ears or a tuner for pitch offsets.
Signal out Out 1, Out 2, Out 3 — three independent DC voltages set by knob pairs. Each Out = A + B summed.
Listen for Silence on its own — this is a CV utility. You hear the effect at the destinations: filter brightness bias, VCO at a chosen octave, comparator firing at a specific level. Two knobs per Out gives coarse/fine feel (use A for coarse, B for fine).
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: 3x MIA, Filter, VCO, Comparator. Signals: 2 cv, 1 pitch.3x MIAFilterVCOComparatorall inputs unpatched · knobs set manual offsets: Out 1cvOut 21v/octOut 3cvCutoffcvV/Oct1v/octThresholdcv121. A1+B1 offset = bias2. octave offsetcvpitch
Mid/side audio summer
Stereo L/R multed into two blocks: block 1 sums to Mid (L+R), block 2 subtracts to Side (L-R).
Walkthrough
  1. Mult stereo L into two copies, and stereo R into two copies.
  2. Patch L copy 1 → A 1, R copy 1 → B 1. Turn both knobs fully clockwise for L+R at unity.
  3. Patch L copy 2 → A 2, R copy 2 → B 2. A 2 fully clockwise, B 2 fully counter-clockwise for L−R.
  4. Keep chain switches up (blocks independent).
  5. Out 1 is the Mid channel (mono sum). Out 2 is the Side channel (stereo difference).
  6. Send Mid and Side through separate processing (e.g. compress the Mid, EQ the Side), then decode back: (Mid+Side)/2 = L, (Mid−Side)/2 = R.
Signal out Out 1 — Mid (L+R). Out 2 — Side (L−R). DC-coupled, so audio passes clean.
Listen for On its own Out 1 collapses the stereo to mono and Out 2 gives the difference — Side often sounds like reverb tails, pan-effects and wide synths while center instruments vanish. Useful for M/S compression, sidechain from ambient content, or stereo-width tricks when you re-encode.
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 8 connections. Modules: 3x MIA, Stereo L, Stereo R, Mult, Output. Signals: 8 audio.3x MIAStereo LStereo RMultOutputA1: full CW · B1: full CWA2: full CW · B2: full CCW (invert)A 1audioB 1audioA 2audioB 2audioOut 1audioOut 2audioOutaudioOutaudioIn LaudioIn RaudioLaudioRaudioMidaudioSideaudioaudio

Behaviors

Attenuverter per channel knob position

Each of the six pots is a full attenuverter: CCW inverts and scales, center zeroes the signal, CW passes non-inverted. DC-coupled so identical behavior on audio, CV, pitch, or gate signals. Useful as six bipolar scalers on a single 6 HP module.

Normalled offset source input jack unpatched

Unpatched input receives an internal DC voltage. The knob then becomes a bipolar offset generator — CCW gives negative offset, CW gives positive. Perfect for adding a pitch transpose, bias, or gate-threshold voltage to a signal on another channel via chain.

2-2-2 configuration both chain switches up

Three fully independent 2-channel attenuverting mixers. Each Out carries its own A+B sum. Behaves like three compact stereo-pannable attenuverting mixers in 6 HP.

4-2 configuration one chain switch down

One block (4 channels worth) sums into a single output while the remaining block stays independent. Convenient when three modulation sources need summing onto one line while a fourth CV stays separate.

6-into-1 configuration both chain switches down

All three blocks daisy-chain into the bottom block's output. Produces a 6-input attenuverting mixer with one output — useful for dense polyphonic sum or combining multiple LFOs into one complex CV shape.

Audio or CV identical any signal type

DC coupling plus high-fidelity pots means 3x MIA behaves identically on audio (handles eurorack ±5V line level) and on CV (keeps 1V/oct accuracy, pitch-summable). Mix audio and CV freely across blocks without worrying about coupling caps.

Controls

Block 1-3 A knob (inner) Inner concentric pot — attenuverter for A input of each block. Center = silent; CCW inverts; CW passes positive.
bipolar attenuverter · center: zero · ±unity at extremes
Block 1-3 B knob (outer) Outer concentric pot — attenuverter for B input of each block. Matches A knob behavior.
bipolar attenuverter · center: zero · ±unity at extremes
Block 1-2 Chain switch Two 2-way switches between blocks 1/2 and 2/3. Down routes that block into the next block's mix; up isolates the block's output. Combinations produce 2-2-2 (both up), 4-2 (one down), or 6-into-1 (both down) configurations.
up: isolate · down: chain into next block

I/O

IN · 2

  • A 1-3
    Inner input per block. When unpatched, an internal offset voltage is normalized, turning the A knob into a manual bipolar offset source.
    NORM → internal offset voltage
  • B 1-3
    Outer input per block. When unpatched, an internal offset is normalized, turning the B knob into a manual bipolar offset.
    NORM → internal offset voltage

OUT · 1

  • Out 1-3
    Summed output of A+B in that block. If the chain switch below the output is down, this output is muted and its signal is instead summed into the next block.