This post aims at providing an overview of the hardware I’m using to turn my Raspberry Pi into a real-time effects processor for my electric guitar.
The Raspberry Pi
The RPi is obviously the star of this setup ! The fact that such a tiny (about the size of a credit card) and cheap (around 30 €) computer can run Pd in real-time is (I think) a small revolution. I had been dreaming of that since many years, actually.
The Raspberry Pi I use in the video is the first commercial version, with 256 MB of RAM. I believe that we can expect some improvements in terms of performance with the latest Revision 2 model (512 MB of RAM). I’ll get you posted when I get one…
The foot controller (DIY)
The pedal I used in the video to trigger the effects is essentially the same as the one I’d been using previously with my laptop. Only this time I put more effort in building it, and it’s nicer, sturdier, and has more buttons and pots. It has a standard Arduino Uno board inside. I read the values from the Arduino with the Pduino external.
The external soundcard
If you’ve read a little bit about the RPi, or if you own one yourself, you are probably aware that it doesn’t have any sound input. The output is fine for applications which do not require high quality audio, but i wouldn’t use it at the moment to plug it into my guitar amp…
So right now the only way to get audio input and output is by using a USB external soundcard. I personnaly use a E-MU 0404 (it the one featured in the video). A few people in the Pd community have been trying different soundcards lately (including a Beringher UCA222 and a Logitech USB To 3.5mm Jack Audio Adapter). There seem to be a few problems at the moment in Raspbian regarding USB 2.0 devices, and I seem to be one the very few lucky ones who can get there soundcard working without having to tweak anything. I hope to have more material soon to write a specific post about this issue.
The “classic” stuff (all the rest!)
The rest of my setup consists of an electric guitar, jack audio cables, and a guitar amplifier. Nothing unusual, except for an audio transformer to connect the balanced output of the soundcard to the unbalanced input of the amp (I already wrote about this in a previous post).