your duo is
world music.

Out of the box, the DUO's keyboard plays a fixed scale. This mod replaces it with a key + scale selection system: pick any root note and any of ten scales, and the ten keys instantly become that scale, rolling into the next octave automatically. Two modifier buttons you already have, BOOST and RANDOM, become a scale modifier and a key modifier when the sequencer is not playing.

how you play it

• Hold BOOST when the sequencer is not playing, tap the arrows to step through 10 scales: Major, Minor, the pentatonics, blues, chromatic, and a few from further afield.
• Hold RANDOM when the sequencer is not playing, tap the arrows to step the root up or down, one semitone at a time, across all twelve keys. Orange denotes sharp, blue denotes flat.
• Let go, and the arrows become octave jumps, BOOST goes back to boosting the tempo, and RANDOM goes back to randomizing. The modifiers only take over while the sequencer is stopped, so nothing gets in the way when a sequence is playing.

the ten scales

Each one gets its own color mood on the DUO's lights when you're picking it, built around how it feels, not just its interval table.

a light show that plays along

• At rest, everything sits at a low, calm glow with colors that subtly reflect the scale selection.
• Play a note, and a rainbow ripples out from your finger and breathes back down. Hold a note and it keeps cycling and pulsing under your hand.
• Circular sequence buttons reflect the selected scale while the light show below pulses.

the detune knob

The DETUNE knob now sweeps the second oscillator across its whole range, from silent to a clean octave up.

• Fully left (counter-clockwise): off. The second oscillator drops out entirely, leaving just the pure tone of oscillator one.
• Around the middle: unison, with only a gentle shimmer either side of centre. The classic slightly-detuned thickness.
• Fully right (clockwise): one octave up. The last stretch of the knob sweeps the second oscillator smoothly up to a clean octave above the note, and holds it there at the very top. Fun to turn while playing live.

is my duo compatible?

Only if it's a Brains 2 unit. Dato has shipped two different hardware generations: an older one (serial numbers below 4630, a different chip and an entirely separate firmware) that this mod can't run on at all, and Brains 2 (serial 4630 and up, i.MX RT1010), which is what it's built for. Your serial number is on a sticker, usually on the underside of the unit.

There are a few board revisions within Brains 2, but you don't need to know which one you have: the only difference between them is minor speaker-mute logic. Worst case on a mismatch, the internal speaker stays muted; headphones, keys, sequencer, and this mod all still work, and a reflash fixes it instantly.