Travel-friendly guitars like the Backpacker from Martin are all fine and dandy if you're into acoustic playing but those of us who prefer electric portability will likely need to seek out something like Traveler's Speedster or Bob Wiley's Ministar. The problem with the latter choice is also having to lug around an amp and cables in order to be heard. Stanford graduates Andrew Penrose and Ari Atkins have developed a go-anywhere electric guitar called the Unlimited that features a built-in, battery-powered amplifier and smartphone-controlled digital effects.

Electric guitars sporting built-in amps are hardly new. An early example of such a guitar is Hofner's Bat, where the amp was positioned above the pickups and covered in a rather attractive branded speaker grill. The Teisco TGR-1 from 1964 had a low output amp powered by two 9-volt batteries and, interestingly, the speaker driver was thicker than the guitar's body so the manufacturer placed a metal dome on the back of the guitar to encase the rear of the speaker.

Then there's the frankly odd-looking Davoli Bikini guitar, where the Kraandal CT642 amp unit was kind of hanging off the body. The first guitar/amp combo I came across with built-in effects was the Fernandez Nomad, with up to ten being available at any one time. Now there's a new kid on the block: the Penrose and Atkins Unlimited.

Penrose told us that while there are a few other guitars with built-in amps already available, "sound quality and versatility is extremely limited, and they don't capture the numerous benefits of smartphone technology." He revealed that the first version of the Unlimited was designed and built by Atkins as part of a mechanical engineering class at Stanford University.

"He had just moved and wanted to build something useful that would be worth carrying around, and was also sick of having to set up all his guitar gear," he said. "His design turned out to solve the problem so well that friends and people he met asked where they could buy one."

The Unlimited features a rather chunky body that's made up of a cast aluminum frame with polycarb plating front and rear. Inside the body is a solid state amplifier with a maximum output of 7 watts and a 5-inch speaker driver (with a 20 ounce/0.56 kg magnet) that sits between two single coil pickups. The amp and speaker are powered by an internal Li-ion battery that's said to be good for up to 40 hours of sound, and can be charged from a standard wall outlet using the included charger. A speaker grill option has recently been added to the design to protect the delicate speaker cone from manic picking antics.

The bridge, tuners, pickups and 25.5-inch scale Maple neck with 20 frets (just two short of a standard neck) are all off-the-shelf components, although the designers say that several different combinations have been tried and tested for the best sound and playability at an affordable price. The guitar also sports a 0.25-inch (6.35-mm) audio output jack that allows the instrument to be plugged into an external amp.

The current model has three knobs circling the three-way toggle switch pickup selector, one for volume, one for gain and the other is an on/off switch. Penrose did tell us that the Unlimited team does intend to combine the on/off circuitry with the volume knob and replace the pickup switch with a tone knob.

The development team is currently busy putting the finishing touches to a free basic iPhone 4 and 4S app package that will accompany the delivery of the instrument to Kickstarter backers who have pledged at least US$275. The guitar is physically connected to the iPhone via an included 3.5-mm headphone jack for connection (which can also be used for private playing through headphones), and the app will allow users to mix in digital distortion, delay, reverb, and EQ effects as they play. Penrose added that "with our current design, latency is essentially negligible."

There is also a tuner, metronome and recording and looping functionality, too. The app is compatible with software like GarageBand and Rocksmith and will allow players to jam along to songs from their iTunes library. It's intended that the ability to upload recorded songs to online portals like Facebook, SoundCloud and YouTube directly from an iPhone will be ready in time for shipment to backers, but will follow shortly after if not.

"In the future we plan to develop interactive lessons, artist/song themed effects pedals, a Guitar Hero-esque signal processing tool to track learning progress and compete with friends, guitaraoke (songs with the guitar track turned off), and release an API so others can develop apps for the Unlimited," said Penrose. "We'll also develop an Android app next year."

Penrose hinted that future designs will incorporate wireless interaction with the smartphone, but is not saying exactly how that will be achieved for the moment.

He did reveal that they intend to develop a beginner model at a lower price once the Kickstarter funding campaign has ended and backers have received their guitars. There are also plans for a higher spec version, a bass model, a keyboard and a set of drums "so the whole band can play/record anywhere."

Commercial availability for the Unlimited electric guitar is planned for March 2013 at a retail price of US$350, which will put it in about the same price bracket as the Pignose PGG 200 Deluxe (that only has a 1-watt amp powered by a 9-volt battery but does have the full complement of 22 frets).

The Kickstarter campaign video below shows the Unlimited in action.

Sources: Unplugged Instruments, Kickstarter page