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Bat Utility Belt: A $20 MIDI Keyboard That Rocks

David Battino

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The Rock Band 3 keytar is crazy-cheap and amazingly useful.

Behold the power of mass production: this two-octave MIDI controller has a keyboard feel that rivals $100 instruments and a price that will astonish you. As of this writing, it’s $19.82 with free shipp­ing. 

How is that possible? The main reason is economies of scale. This gadget is essentially a video game controller with a bonus MIDI Out jack. When it launched in 2010, the companion Rock Band game was selling like crazy. That let the manufacturer (fittingly named Mad Catz) make gazillions of units with good quality and a low price. Then suddenly the game stopped selling. Mad Catz went bankrupt and sold off its assets, which apparently included shiploads of keytars. What had been a good deal at the original $79.99 is now 75% off.

That makes the Rock Band 3 keyboard (RB3K) another great fit for the Bat Utility Belt series, where I cover surprisingly useful synth gadgets that cost $100 or less.

The Rock Band 3 keyboard is a remarkably capable MIDI controller (see table below). The four buttons at right change the octave and MIDI program number. The three adjacent buttons send Start, Stop, and Continue commands. Pressing the top of the four-way rocker switch enables Drum mode for keyboard splits. The 3.5mm jack on the right accepts a pedal.

Play the Keytar; Play Them Drums

Keytars are inherently amusing performance instruments. I originally bought my RB3K to play my LED cowboy hat like an electric troubadour. The RB3K’s toy-like look makes it even more fun, yet it’s built from thick plastic to survive intense video gaming sessions. At 4.6 pounds, it’s easy to wear with the included strap, and rubber feet let you play it on a stand or desk like a normal keyboard. It comes in three versions—for Xbox, PlayStation, and Wii. All have the same MIDI features, so I chose the Wii version, which is the cheapest.

The 25 keys are velocity-sensitive and even transmit release velocity. The action is at least as crisp as most $100 controllers I’ve played, and these keys are full-size. The top octave always transmits on MIDI channel 1. Rocking the four-way switch upward toggles Drum mode, which assigns the bottom octave to channel 10. With a General MIDI sound module, that creates a split-keyboard effect with drums on the lower keys and chords or leads on the top. Of course, if your synth allows it, you can assign any sound you like to channel 10.

MIDI Modulations

It wouldn’t be a keytar without a neck poking out, and this one sports a stubby ribbon controller. Sliding your finger to the left sends CC1 (modulation); the value stays where you last touched. Holding the Overdrive button makes the ribbon send pitch-bend data instead. The range is two semitones up and down from the ribbon’s center. The pitch snaps back when you lift your finger.

Unfortunately, the ribbon’s resolution is coarse. The values jump by 5 or 10 units (or more), so you get only about 20 values in the 0–127 range. I found that okay for vibrato, but lumpy for filter sweeps. Pitch-bend was especially hard to control because you get only half the ribbon’s length and there’s a glitchy zone at each end. (Plus, you have to hold a button while sliding your finger.) The keys exhibit this reduced resolution as well: I got about 20 discrete velocity values out of 127, and the lowest I could play was 10. 

Of course, if you’re bouncing around a stage with a $20 plastic keytar, you and your fans probably aren’t too concerned about precision. And the good news is that the RB3K runs for hours on three AA batteries. I was hoping it would also transmit power through the MIDI jack so I could play my tiny Ploytec PL2, but that will have to be a future DIY project.

Hacking It

Speaking of DIY, there’s nothing like a 20-buck musical instrument to get the ideas flowing. I started by plugging a potentiometer into the 3.5mm TRS pedal jack. I followed the Roland EV-5 expression pedal format, with the pot’s wiper wired to the tip of the plug, but it had no effect on expression or volume. (See the MIDI command table below.) I did notice that when I turned the pot all the way down, it triggered the MIDI sustain command (CC64), which means that shorting the tip to the sleeve functions as a damper pedal. So, if you have a standard “normally open” footswitch, you can attach a 1/4-inch-to-3.5mm mono adapter to the plug and sustain your keytar. I searched in vain for the proper expression pedal wiring format; if you know, please contact us. 

This ambitious maker added an Xbee modem to turn his RB3K into a wireless MIDI controller. His tutorial is fascinating for the keytar teardown photos alone. A comment at the end shares another clever idea: a switch to default the ribbon to pitch-bend and convert the Overdrive button into a sustain control.

Another brilliant hacker stuffed an M-Audio MIDI-USB interface and Apple USB-Lighting adapter inside his keytar so he could play samples on an iPod Touch.

The Rock Band keytar is a favorite of hackers. I velcroed a battery-powered speaker and General MIDI module to mine for mobile jams. The module is the endearingly wheezy MIDIPlus MiniEngine.

MIDI Command Reference

None of the buttons on the RB3K is labeled with its MIDI function, so here’s a cheat sheet with buttons grouped from left to right. (The Overdrive button is on the neck.) I was unable to verify the pedal-mapping commands because I don’t have a compatible expression pedal. With a simple tip-shield switch, the pedal jack always controlled sustain.

For more details, see this PDF draft of the manual on synth hacker David Green’s site.

ButtonAction
OverdriveMap ribbon to pitch-bend (normally modulation)
Rocker UpToggle Drum mode (keyboard split)
Rocker DownMap pedal to volume
Rocker LeftMap pedal to expression
Rocker RightMap pedal to sustain
Trio LeftStop
Trio CenterContinue
Trio RightStart
Quad LeftOctave Down
Quad RightOctave Up
Quad UpProgram Increment
Quad DownProgram Decrement
 
Combinations 
Trio Left + Right + CenterAll Notes Off (channels 1 & 10)
Quad Left + RightReset octave
Quad Up + DownSet program to 0

What’s in Your Utility Belt?

Tell us about your go-to music gadgets. Post the details on FacebookInstagram, or Twitter and tag your nomination #BatUtilityBelt. You can also reach me through Batmosphere.com. If I feature your submission in an upcoming column, you’ll win a free subscription to Synth and Software. Oh, wait—that’s free already. Kapow!

Website: Amazon  (As an Amazon Associate, the author earns from qualifying purchases.)

Price: Approximately $20

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