For some months now I’ve been planning on doing a bunch of stuff to one of my guitars. A couple of years ago I bought a very old (built in 1977) guitar. The guitar was heavily modified (which meant the “original” value was not very high) and had a funny little sound. But I fell in love with it kind of how some embedded folk are in love with the 8051 CPU even being such an old CPU. It has this beautiful wood colors and the neck is amazingly easy to play. Those of you who play guitar should understand, those of you who don’t, imagine the best compiler that could ever exist…and it’s incredibly well documented as well – nay! Imagine the documentation is so good that you only have to think about what you want, and the document will pop up in your computer screen, in the exact page and paragraph you need to read…that’s how much I love this guitar. There’s also the fact that it’s old and uncommon, kind of like bragging that you can program in COBOL.
Yesterday I decided to start this project. I had bought some things in advance and was now basically ready to start soldering.
Sorry for the bad picture quality, I’m a engineer/guitarist, not a photographer. This picture was taken when I had removed mos of the internal electronics and was fitting the new pickups (or pups as we guitarists call them). Pickups are the magnetized coils used in electric guitars to sense the string vibration (just a cultural note). The old pickups on this guitar were particularly bad, I don’t know if it’s the kind of sound they liked in the seventies, or if they were too old, probably the input impedance in old amplifiers was different as today’s amplifiers (because of valve technology vs semiconductor technology), I don’t really know. The important thing here is that the original sound sucked to my ears (and that, of course, is subjective) so I wanted to change the pickups. Sorry to disappoint those of you extreme home-project builders: I didn’t wind my own pickups, I want this guitar to sound awesome, so I bought some pickups that I know will sound awesome. Now I’m looking into the right combination of potentiometers and filtering capacitors to get everything sounding as cool as it sounds in my head.
But I noticed something: there’s some extra room inside of my guitar back panel. The guitar used to have a bunch of switches to configure the pickups in all sorts of ways, I won’t be using all of the switches as the original configuration because I find some of the attainable sounds a bit redundant so now I’ll end up with some extra holes that will not look so nice. But then I got thinking about this effects pedal that I own that is some sort of audio signal processing development platform created by Freescale Semiconductor and Line6 (a guitar effects and accessories company which specializes in guitar amplifier and effect digital modeling). This little pedal (called the Tone Core) I own has an integrated USB bootloader with which you can load DSP code to the on board Freescale audio processor. The USB bootloader is controlled by an 8-bit USB MCU also from Freescale. The Audio DSP platform is a free Eclipse-based compiler and Line6 provides some example code to build an equilizer or a tremolo (volume swirl) effect. Based on those codes you can start writing your own effects from scratch. There is even an independent Tone Core wiki where people can post their effect code, and some videos on YouTube of people playing with the effects they’ve made.
So now I’m thinking that if I remove the metal chassis and just find a way to stick the effect pedal electronics into the guitar electronics chamber and use the extra holes that are already there to put the effect pots there, I might get to have some sort of freak reprogramable guitar…and I’m a fan of freak embedded stuff! Before you start telling me not to do the freak thing, consider this: Gibson, one of the most important guitar companies out there, has it’s own flavor of freak guitar, the Dusk Tiger. It’s not only a freak guitar, in my opinion, it’s one of the coolest embedded systems out there. Just a little bit of the specs:
– Robot guitar: this is what Gibson is calling their automatic string tuning system. It’s crazy, each tuner has a tiny stepper motor, and at the other end of the string there’s a piezo-electric sensor. You play all the strings at the same time and a processor inside the guitar determines the tuning on each string and adjusts the littler stepper motors accordingly. The guitar can be completely out of tune and re-tuned in seconds.
– Digital EQ with presets: a little knob allows you to choose from a bunch of EQ presets to output different sounds.
– Configurable: if the previous characteristics weren’t enough, you can plug the guitar into a computer and, via custom software, load new settings to the guitar, different equalizer settings or tunings.
Please visit the link to the Dusk Tiger, it’s such a weird and amazing guitar full of embedded systems wonder: motor control, digital signal processing, LEDs, connectivity, all sorts of fun!
So after writing this article I still haven’t decided if I’ll turn my guitar into a freak…any opinions?