Maus EQ

Keyboard-mappable DJ EQ. A dual-channel MIDI EQ + volume controller you can drive entirely from the keyboard — bind each EQ band (highs / mids / lows) and each channel's volume to a hotkey and boost, cut, or kill hands-free when your controller is out of reach. Prefer the mouse? Hold a knob to ramp it; hit a button to reset or kill.

It outputs MIDI directly over its own virtual port (Maus EQ), so it maps into rekordbox / Traktor like any controller. Two channels, three EQ bands each (HIGH / MID / LOW) plus channel volume. macOS only (CoreMIDI).

Architecture

mouse / keyboard → Electron UI → IPC → midiout (Swift, CoreMIDI virtual source)
                                            → MIDI CC on port "Maus EQ"
                                            → rekordbox / Traktor (MIDI-mapped)

native/midiout creates a CoreMIDI virtual source and emits Control Change messages. Values are absolute and tracked in-app, so up/down stay in sync, reset is exact, and nothing drifts.

Interaction

• Keyboard (the main event): every EQ band — and each channel's volume — is bound to a key. Tap to step by a fixed amount (5), hold to auto-repeat. Map the controls once in your DJ software and mix the EQ entirely from the keyboard. See the mapping below.
• Hold a knob (press and keep the mouse button down) to ramp it in that direction; release to stop. The ramp rate is the STEP slider in settings.
• RESET jumps the band to centre (64); MIN kills it to 0.

Scene macros

Whole-mix actions in the scene bar — each with a keyboard shortcut:

• BASS SWAP (B) — kill the bass on one deck and bring it up on the other; press again to swap back. The button shows which deck currently holds the bass.
• EQ RESET (R) — return every EQ band on both decks to centre (volume left untouched).
• PREP 1 / PREP 2 (3 / 4) — prep a deck for an incoming track: kill its bass and dip mids/highs below neutral (LOW 0, MID 48, HIGH 48). Tune via the PREP_LOW/MID/HIGH constants in renderer/app.js.

Keyboard & MIDI mapping (value 0–127, centre 64)

Channel (MIDI ch)	Band	CC	Down	Up
CH 1 (ch 1)	VOL	7	1	2
CH 1 (ch 1)	HIGH	16	q	w
CH 1 (ch 1)	MID	17	a	s
CH 1 (ch 1)	LOW	18	y	x
CH 2 (ch 2)	VOL	7	9	0
CH 2 (ch 2)	HIGH	16	o	p
CH 2 (ch 2)	MID	17	k	l
CH 2 (ch 2)	LOW	18	n	m

Volume uses the standard MIDI Channel Volume CC (7) and starts at full; its buttons are MAX / MIDDLE / MIN (EQ bands use RESET / MIDDLE / MIN).

Edit renderer/app.js (CHANNELS, and the tuning constants STEP, TICK_MS) to taste.

Run

npm install     # compiles native/midiout via postinstall
npm start

Connect to rekordbox

1. rekordbox → Preferences → Controller / MIDI → enable Maus EQ.
2. Use rekordbox MIDI learn: select a deck's EQ knob, then turn the matching control here — it binds to that CC.
3. Repeat for all six bands across the two decks.

Rebuild the helper

npm run build:helper