Bitbox Micro Firmware: The Master EQ and Filter

A multi-algorithm master EQ and filter across the whole mix. Ten algorithms on one encoder. See devices for where it sits, and the compressor for the other one.

Where the compressor controls dynamics, this one controls tone and colour. Ten modes sit on one encoder: filters first, a DJ sweep and a dual cut and a band pass, then shelving and bell EQs, a notch, a phaser and a vowel morpher. One knob picks the character. Three more play it.

It runs on the sum of everything routed to Out 1 and 2, after the delay and reverb returns. So it takes the tails with it, which you hear and which is the point. Pads on Out 3–6 stay clean.

The module offers no EQ of any kind. No page, no menu, nothing in the manual, and nothing you can assign. Where the rest of this patch reaches controls the module already had, this one adds brand new features that have never been available on the hardware.

1Centre Is Always Neutral

One rule holds the whole design together, and it is worth knowing before you touch anything. Every control is neutral at its centre position, in every mode. Three knobs centred is an EQ doing nothing at all, whichever mode you are in.

That is what makes ten modes playable from one panel. You can sweep the mode dial with the controls centred and hear nothing from the EQ the whole way, then pick a mode and move one knob. It also means a control's own centre is a real bypass for that control, so you can back out of anything by returning it.

On a controller with endless encoders there are no detents to feel for, so give each of the three a centre-line LED style and a reset-to-middle gesture. You will use both constantly.

2The Ten Modes

Every mode has been heard and tested on hardware.

#	Mode	Encoder 2	Encoder 3	Encoder 4
1	DJ Filter	filter, dull to thin	resonance	knee
2	Dual Cut	high cut	low cut	resonance
3	Band Pass	centre frequency	width	gain
4	Mixer EQ	high	mid	low
5	Tone + Filter	high	low	filter, dull to thin
6	Tilt	tilt	hinge frequency	—
7	Notch	frequency	Q	depth
8	Peak	frequency	Q	gain
9	Phaser	sweep	depth	spread
10	Formant	vowel, I to U	intensity	shift

The first five, briefly. DJ Filter is the classic one-knob sweep: anticlockwise closes to a dull thump, clockwise thins to hats. Dual Cut gives you both ends separately. Band Pass isolates a band you can move, narrow and lift. Mixer EQ is a three-band desk EQ. Tone + Filter puts two shelves and a filter on one panel.

Then the rest. Tilt is a see-saw, lifting the treble by exactly what it drops the bass. Notch and Peak are one surgical cut and one sweepable bell. Phaser sweeps four notches together as one body. Formant parks three bells on the resonances of a human vocal tract and morphs between vowels.

Ten algorithms across three encoders is an enormous amount of sound design to go at, and this guide stops at what each control does. What any of it does to your own material is the interesting part, and there is far more of it than could be written down. That is yours to explore.

3Working the Four Encoders

Nine CCs, all on MIDI channel 1, like the compressor.

Control	Turn	Push
Encoder 1	CC 50 — mode	CC 57 — master bypass
Encoder 2	CC 51	CC 54
Encoder 3	CC 52	CC 55
Encoder 4	CC 53	CC 56
A button	—	CC 59 — filter slope, 12 or 24 dB

Encoders 2, 3 and 4 want a plain linear encoder across the full range. The mode encoder is the fussy one. Set it to ten steps running from 6 to 122 rather than the full sweep. Ten windows across 128 values are about thirteen wide, and a full sweep lands a step within one value of a boundary, which makes dialling a mode unreliable. Starting at 6 and stopping at 122 centres every step with six values of margin.

Send CC 50 as plain 7-bit. A 14-bit pair would put its second half on CC 82, which is inside the per-pad range, and you would be moving a pad's granular window every time you changed mode.

4Kill, Open and Slam

The pushes are the performance controls, and they are all momentary. Hold to act. Release to return. What comes back is the encoder's own position, untouched, so nothing jumps.

Three different things, deliberately not sharing a word:

Gesture	What it does	Where
Kill	that range disappears from the mix	Mixer EQ's three, Tone + Filter's two
Open	that band stops acting, letting more through	Dual Cut, Band Pass width, Tone + Filter's filter
Slam	forces a control to maximum effect	Notch, Tilt, Peak, Phaser, Formant

Sixteen pushes do something across the ten modes. The rest are unassigned, and on those you are better off spending the push on a reset-to-centre gesture instead. Most controllers let you flip a push between sending its CC and centring the encoder locally, one setting, no re-entry. Expect to flip it.

5Bypass and Slope

CC 57 takes the whole EQ out. Press once and it is gone, press again and it is back. It is latching rather than momentary, and it is the one push on encoder 1 worth spending a CC on, because a mode dial has no meaningful middle to reset to.

CC 59 switches the filter slope between 12 and 24 dB per octave, on the modes that have one. Set it up as an on-off button. Band Pass is the exception: there its gain control needs the same bands, and gain wins.

6How the EQ Arrives

It powers on in DJ Filter, all three controls centred, bypass off and slope at 12 dB. So a freshly flashed module sounds exactly as it did before. Centred controls pass everything through.

Its settings behave like the compressor's. They survive a preset change, and a power cycle puts them back to the boot state above. See what they have in common.