Adventures in DIY: Hacking Pocket Miku, The Singing Stylophone

Hatsune Miku lets producers build complete vocal performances by manipulating syllables
By David Battino ,

Q: What do you get when you combine a singing synthesizer with a dancing hologram?
A: Hatsune Miku, the helium-voiced virtual idol who sells out shows from Tokyo to Los Angeles.

Miku is the manga-eyed face of Yamaha’s Vocaloid technology, which enabled ambitious producers to build complete vocal performances by manipulating syllables on a computer screen.

For years, Yamaha toyed with turning the tech into a real-time instrument. (Check out the fantastic prototypes at vocaloid.com/vocaloidkeyboard.) The company is reportedly about to release a Vocaloid keytar. But in 2014, the Japanese science-kit company Gakken launched a cheerful gadget called Pocket Miku that pairs a Yamaha Vocaloid chip with a ribbon keyboard. You can now buy the Pocket Miku (aka Gakken NSX-39) for as little as $21.

The synth is instantly accessible: Power it up with three AAA cells (or USB) and tap out melodies with the included stylus. Choose different vowels by pressing the A-I-U-E-O buttons, or select preset Japanese phrases by pressing Vibrato or Shift and one of the vowels. Slide the stylus to the top of the ribbon, and suddenly pitch isn’t quantized anymore. You can swoop up or down for crazy effects (see Figure 1).

Fig. 1. For an extra-portable setup, I use a battery-powered USB hub and the Midi Tool Box app to play Pocket Miku from a CME Xkey.

Interestingly, every key transmits an F#; moving left or right applies just the right amount of pitch-bend to play the next semitone. If you have a softsynth that allows you to set the bend range to 16 semitones (I used Reaktor), you can use Miku as a unique USB MIDI controller. (Alternatively, set the softsynth’s range to 8 semitones to play quarter-tones.)

The fun really starts when you fire up Gakken’s Web MIDI apps to customize Miku. Like the manual, they’re entirely Japanese, so I highly recommend reading Paul Drongowski’s hands-on Miku blog at sandsoftwaresound.net. (You can also download an English manual from Adafruit.com, the original US distributor.)

Fig. 2. Gakken’s Web MIDI app lets you download new phrases to Pocket Miku. Here I’ve set the Shift-I preset to sing “Electronic Musician” in Japanese.

Connect Miku to your computer via USB, then launch the Google Chrome browser and go to http://otonanokagaku.net/nsx39/app.html. One app lets you download 15 new phrases to Miku. The catch is that they have to be in hiragana, one of the Japanese phonetic alphabets. I typed English phrases into JapaneseTransliteration.com and copied the hiragana output to make the phrase in Figure 2. Click E to edit the phrase, then press Return to transmit it to Miku. (Chrome’s built-in translation helps sort this out.)

Another Gakken app updates the Miku firmware with several helpful features. After updating, pressing “I” and the down arrow will turn off the reverb and speaker EQ for cleaner recording, and pressing one of the arrows while a note is playing will add harmonies.

The harmony trick foreshadows one of the NSX-39’s coolest features: The chip that powers it is also an XG-compatible synth. (XG is Yamaha’s extension to General MIDI, adding effects such as the harmonizer and extensive MIDI modulation.) I used Midi Tool Box (mtb.artteknika.com) to send the f0 43 10 4c 02 01 40 4e 00 f7 SysEx command to Miku, changing the harmonizer to an autowah I could then control with CC 94, Variation Depth. Sugoi!

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