Raspberry Pi becomes a guitar effects processor

guitar

One of the more interesting use cases for the Raspberry Pi is exploiting its DSP capabilities in interesting ways. There’s a lot of horsepower inside the Raspberry Pi, more than enough to do some very interesting things with audio, all while being powered by a small wall wart adapter. [Pierre] over on the Pure Data mailing list has a proof-of-concept working that uses the Raspi as a guitar effects processor. The results are very encouraging – [Pierre] is able to use his Raspi as a delay, pitch shifter, and of course a classic flanger, phaser, and chorus with a latency of about 16 ms.

There are a few steps necessary to get low latency with the Raspi’s audio interface. [Pierre] is running his Pi headless, and allocated more RAM to the CPU.

If you’d like to try this out for yourself, [Pierre] has a tutorial for setting up Pure Data with the Raspberry Pi. He’ll be updating his blog soon with more tutorials and verified USB audio interfaces later.

Check out the processor in action after the break.

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Putting guitar pedals in a web page

Only half of playing guitar – according to a few musician friends of mine – is moving your fingers up and down a fretboard and banging out some chords. The other half is the artistry of mastering your tone, usually through amp settings and stomp boxes.

Effects pedals – little boxes of electronics that go between the guitar and amp – are able to amplify and distort a guitar’s output, add reverb and delay, and even filter the tone via a wha or envelope pedal. These pedals can be simulated in software, but we can’t believe that they can now be emulated completely in JavaScript.

Pedalboard.js is a project put together by [dashersw], and aims to put a slew of pedals ‘in the cloud’ and turn editing and effects board as easy as building a web page.

The project is built around Webkit’s W3C audio API, allowing this virtual pedal board to work in Chrome, Safari, and other Webkit-enabled browsers. Pedals are programmed as nodes, each configurable to have and input, output, or analyzer that is able to modify the gain, wave shape, or filter of anything received by the line in on your computer.

Thee is a small demo of Pedalboard.js available here with a pre-recorded guitar track feeding into a few stomp boxes. It’s a pretty cool idea if you’d like to play around with a few guitar effect, but we can’t wait to see this bit of JavaScript implemented by effects pedal manufacturers allowing us to try before we buy.

Fabbing a guitar tremolo stompbox

There’s a lot of builders around whose first foray in electron manipulation was building effects pedals for guitars. It looks like [Dino] might be getting back to his roots with his tremolo effects box how-to.

Last week, [Dino] found an old 5-watt tube amp in someone’s trash and decided to bring it back to a functional state. With his new trem effect, it looks like [Dino] might be getting the band back together.

Apart from tiny boost circuits, a tremolo is generally the simplest effect pedal you can make. All you’ll need to do is vary the amplitude of the guitar’s signal at regular intervals. After that, it’s only a matter of pretending you’re playing through a rotating Leslie speaker.

To get his trem working, [Dino] set up a 555 circuit to flash a LED at regular intervals. This LED is encased in heat-shrink tubing along with a photocell. This setup controls an LM386 amplifier. The build is really simple, but from the video after the break we can tell it sounds great.

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