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Guitarduino sonic laboratory packs touch and tap FX control

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July 2, 2013

The Guitarduino from Igor Stolarsky

The Guitarduino from Igor Stolarsky

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In addition to being a talented player and having a guitar named after him, Les Paul was a dedicated tinkerer. It's rather fitting, then, that one of those famous guitars has been modified to include touch-controlled synths and effects, and an onboard drum machine. The system is built around an Arduino brain externally mounted near the bridge, which routes signals from sensors and buttons through custom code to a preamp/effects processor or a digital audio workstation suite. As you can see and hear from the video after the jump, the aptly-named Guitarduino is quite simply extraordinary.

Igor Stolarsky has a Bachelor of Science in Computer Science, and studied at Berklee College of Music for six semesters before landing a position as staff engineer for Futura Productions in Roslindale (MA). He's also the guitarist with rock band 3's & Sevens, and is now the inventor of the Guitarduino. Before we go into exactly what that is, have a look at the short demo video below to get a taste of its capabilities.

The guitar onto which the electronics are mounted is a black beauty road warrior called the Les Paul GT. At the bridge end of the instrument sits an Arduino Uno development board topped by a Proto Shield. Three Force-Sensing Resistor (FSR) touchpads are taped to the front of the guitar, and there's another long touch strip running along the back of the neck. The upper pad is programmed to be a filter with step sequence modulation. Stolarsky has positioned a pitch shifter pad just below the strings, inbetween the humbucking pickups, and the pad underneath the neck pickup launches a synth vibrato effect.

The sensor strip on the back of the neck acts as one long button that can be activated wherever Stolarsky happens to be playing. As well as holding an effect after the player has released a pad on the front, the strip can also be used to change effect parameters on the fly. The Guitarduino's creator told us that he's just added another FSR, and is waiting for a HotPot membrane potentiometer to arrive.

Readings from touchpad sensors are processed through Max/MSP and transformed into MIDI, before being routed to an Axe-FX II preamp/effects processor from Fractal Audio.

The sensor strip on the back of the neck acts as one long button

The Arduino board is also home to six colorful arcade controller buttons, which are hooked up to Ableton Live. Percussive sounds are assigned to three of them, one acts as a stutter switch, and the remaining two facilitate live looping. The audio signal picked up by the GT's humbuckers is fed directly into the Axe-FX.

"All of the guitar sounds you hear are coming from the Axe-FX, the pads and buttons just work as on/off sensors and then Max generates MIDI data (sometimes creatively) to tell the Axe-FX what to do," explains Stolarsky. "I could trigger the same effects with my FCB1010 foot controller if I wanted to."

In fact, he's currently using the FCB in conjunction with the mounted setup to expand the instrument's capabilities even further.

"I use the FCB for more controls, mostly it's controlling Ableton," he reveals. "I didn't use it in the initial video but it'll get a pretty good workout in the one we're working on now. I've got the Uno firmware so its functionality is a little expanded past the standard 1010. I'm using the stomps to do things like start and stop Ableton and individual clips, triggers samples, mute/unmute certain elements of the track, and move between song sections. I've got some of them set up as momentary switches so I can be pretty fast about triggering them without too much tap dancing. The expression pedals can do the standard guitar things like wah and whammy but I can also use them for filter sweeps, and whatever else I come up with. I've got certain things automated so that I can still move around a little without being completely glued to the board, but I do like to perform as much of it live as I can."

There's also talk of adding an accelerometer or a d-beam for control of effects using gestures/movement, so this project is definitely what you might call a work in progress. As such, the USB-powered mounted electronics are to remain exposed for the moment, which, in my opinion, only serves to add to the Guitarduino's appeal.

"For now, I'm going to leave it exposed because I'm still adding stuff to it," he confides. "This is also still a prototype in my mind and I'm constantly making changes as I think up new things to do with it so I probably won't try to house it until the next version. My initial intent was to have it be wireless and powered off a battery but after I couldn't get the wireless latency low enough, I ditched the battery as redundant when I switched to USB."

The Les Paul GT now features an Arduino Uno, Force-Sensing Resistor touchpads, and six col...

Curious about whether the setup was gig-friendly, I asked Stolarsky if the Guitarduino could be used in a live setting or whether he has to be shackled to a computer running MSP and Ab Live.

"It does require my Max patch to work, but that hardly precludes me from using it live," he explains. "In fact, using it live was the whole idea behind making it; I wanted to be able to perform all of these effects you usually only hear coming off a backing track. I need to have a laptop with me, but that's not exactly uncommon these days and the Axe-FX is great live. Doing it this way lets me play venues that are otherwise only set up for a DJ and still bring the live performance aspect to a show."

"I'd like to get something like a 2x12 cab and a power amp at some point for stage volume, but for now I'm keeping it as minimal as possible," he adds. "So, the sound you hear in the video is pretty much exactly what I would be sending to a PA."

Though he has no plans to release schematics or code, the video below shows Stolarsky explaining how the various aspects of the system work together to produce those fluid effects.

Source: Igor Stolarsky via GeekBoy

About the Author
Paul Ridden While Paul is loath to reveal his age, he will admit to cutting his IT teeth on a TRS-80 (although he won't say which version). An obsessive fascination with computer technology blossomed from hobby into career before the desire for sunnier climes saw him wave a fond farewell to his native Blighty in favor of Bordeaux, France. He's now a dedicated newshound pursuing the latest bleeding edge tech for Gizmag.   All articles by Paul Ridden
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