Review: Percussa AudioCubes

SHINE ON, YOU CRAZY DICEBONUS MATERIALDressing Up a Square and pdf of specifications.
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FIG. 1: AudioCubes use four infrared emitter/detectors to sense nearby objects and communicate with each other. A USB interface puts your computer into the conversation as well.

Down in the “mad scientist” hall of the 2007 NAMM show, I stumbled across fascinating new MIDI controllers and lo-fi audio processors from a small Belgian company. Percussa AudioCubes communicate with each other and with nearby objects by means of infrared light, translating your gestures into data that can drive MIDI software (see Fig. 1). They also respond to MIDI data over USB by changing colors, allowing you to create a desktop light show. Quarter-inch jacks enable them to process analog audio. The approximately 3-inch-square battery-powered AudioCubes can even generate sound on their own and beam it between themselves, forming a wireless modular synthesizer.

By the 2008 NAMM show, Percussa had moved upstairs to the main hall, refined its software, and lined up dealers around the world. As of this writing, the company still has no U.S. dealer but offers international shipping for about $20 for orders placed on its Web site.

CUBES IN A BOX

AudioCubes are the brainchild of Bert Schiettecatte, a young Belgian musician and programmer who became interested in “tangible musical interfaces” while earning his master's degree at the Stanford Center for Computer Research in Music and Acoustics (CCRMA). AudioCube development is partially funded by a grant from the Belgian government.

Percussa sells the cubes in sets of two or four. Inside the box you get the cubes, a USB cable, and a disc with software, audio loops, and PDF manuals. You can connect as many as four cubes to a single computer via USB, but once the cubes are configured, you can unplug them to let them talk among themselves, so to speak.

The cubes are constructed of two U-shaped pieces of milky plastic that glow when lit by the high-intensity, tricolor LED inside. Perhaps to create an unblemished top surface, the two halves are connected only at the bottom. Three screws attach one half to the circuit board, which in turn slots into several cutouts in the other half and rests on three protruding jacks (see Fig. 2 and Web Clip 1). This unreinforced design means that the cube's top face wiggles and two of the sides flex inward when grasped. Combined with their sharp edges, that produces a creaky, unfinished feel.

A power button resides on the bottom of each cube. An internal rechargeable battery drives the electronics when the cube is not connected to a computer, but the cube forgets its programming when you turn off the power.

Two LEDs pierce each of the four vertical faces; one LED in each pair sends signals and the other detects them. In addition, one face contains an audio input, one contains an audio output, and a third contains the USB jack. These cables may get in the way as you start to move the cubes around.

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FIG. 2: Unlabeled -inch jacks on the left and right handle monophonic audio output and input. The rechargeable battery is underneath the foam, with the power button and USB jack directly behind.

CROSSING THE MIDI BRIDGE

To communicate with MIDI software, AudioCubes use a program called MIDI Bridge (Mac/Win), written in Cycling '74 Max/MSP (see Fig. 3). On Windows (which I used for this review), you need to download and install a third-party utility called LoopBe that functions as a secondary bridge between MIDI Bridge and your music software. LoopBe worked flawlessly, even muting the MIDI stream and notifying me when I accidentally created a MIDI feedback loop.

Before building those bridges, I updated the cubes' firmware with another Percussa program, Firmware Upgrade. Thanks to the clear PDF instructions, it was one of the easiest firmware updates I've ever done.

MIDI Bridge allows you to set each USB-connected cube to one of three modes: Sensor, Receiver, or Sender. In Sensor mode, a cube acts like a Roland D-Beam; each vertical face becomes a motion detector, sensing the proximity of nearby objects and translating it into MIDI Control Change (CC) values. You can set each face to a different sensitivity, set upper and lower CC limits, and invert the response. Oddly, the default is to lower the CC value as the object — your hand, for example — nears the cube (the detection range is about 14 inches). Percussa's online forum explains how to calibrate the sensors, but I had a hard time getting repeatable results.

In Receiver mode, the USB-connected cube works with a second cube you've set to Sender mode. Each face on the receiver can be mapped to four MIDI note values. Depending on which side of the sender cube is facing it, the receiver will trigger one of those notes (the sender does not have to be connected to the computer). If you place a sender next to a receiver and spin it, you'll trigger the four notes in a row. Move the sender to face another side of the receiver, and you can get four different notes. I had to align the transmitters and receivers closely to produce reliable triggers.

The well-written manual explains how to use this technique to trigger clips in Ableton Live (a demo version is included, along with a song containing 16 clips — one for each face-to-face combination). You could also use send/receive pairings to select patterns in Propellerhead Reason. A template song is included for that, too, and a Remote codec should be available by the time you read this. And, of course, any other software that responds to MIDI notes or CCs is fair game as well.

Firing off clips in Live by twisting cubes was amusing, but what I really enjoyed was sending CCs back down the wire from Live to change a cube's color in sync with the music. CCs 14, 15, and 16 control the internal red, green, and blue LEDs, respectively. By mixing values, you can theoretically produce any of 4,096 colors. I found it easy to create rhythmic flashing effects by sending single CCs, but changing several controllers simultaneously caused the display to lag; Percussa suggested reducing the sequencer's step resolution so that it sends out fewer CCs per second.

AUDIO PROCESSING

AudioCubes' most unusual feature is their ability to process audio and transmit it over infrared to adjacent cubes. With enough cubes, you could set up an optical modular synthesizer — patching oscillators, sample players, granulators, and distortion effects together in ever-changing ways — simply by shuffling boxes. The circuitry has 9-bit, 32 kHz resolution, which produces a cool lo-fi effect (see Web Clip 2).

AudioCubes currently offer 12 synthesis and processing algorithms that you configure with another Max/MSP patch. Some parameters can be altered on the fly by signals from adjacent cubes. Percussa currently regards the audio functions as experimental and thus skips over the details in the manual, but it gave me some preliminary documentation (see Web Clip 3).

I initially had trouble aligning the cubes precisely enough to establish optical audio flow. Percussa suggested moving them farther apart to prevent the sensors from saturating, which helped.

SQUARE DEAL?

A pair of AudioCubes costs $399, and a set of four will set you back $699. It's hard to put a monetary value on such a unique device, of course. Similar tangible interfaces with visual feedback exist only in labs and universities, and most require pricey projectors and bulky furniture (see Web Clip 4 for an extensive list). Boutique instruments naturally cost more, but you usually pay more for anything unique. Consider, too, that AudioCubes look striking, work with popular software, and offer enormous potential for customization. Inventor Bert Schiettecatte fairly bubbles with ideas, and his Max-based development system allows him (and savvy users) to implement new features quickly.

However, the construction of the cubes is flimsy. They just feel cheap, with sharp edges, creaking joints, and a wiggly top panel. On the other side of the die, so to speak, the type of DIY performer who'd be most attracted to AudioCubes would probably enjoy repackaging their electronics into custom housings. The circuit board's design should make that relatively easy.

A bigger question is how well the cubes facilitate musical expression. Throughout history, the instruments that have succeeded are the ones that fluidly map gestures to sound, supporting both nuance and drama as well as a path to virtuosity. I can imagine AudioCubes coming alive in the blazing hands of a juggler or turntablist, but I found the sensors too inconsistent to allow satisfying control. At present, AudioCubes shine as a cool-looking device for experimentation and live performance. Only you can say whether that novelty justifies the boutique price; the results will depend on your creativity.

David Battino (batmosphere.com) is the coauthor of The Art of Digital Music (Backbeat Books, 2005) and the audio editor of the O'Reilly Digital Media site (digitalmedia.oreilly.com).

PRODUCT SUMMARY

MIDI controller and audio processorset of two$399set of four$699

PROS: Exotic look. Flexible software. Huge DIY potential. Phlegmatic lo-fi sound.

CONS: Flimsy construction. Inconsistent sensors. Volatile memory. USB cable may block one sensor. Expensive.

FEATURES 1 2 3 4 5 EASE OF USE 1 2 3 4 5 DOCUMENTATION 1 2 3 4 5 VALUE 1 2 3 4 5

Percussa
percussa.com