Guitar with embedded raspberry pi

[ds1239]

Hello. I am planning on purchasing a build-your-own-guitar kit, and embedding a raspberry pi in the guitar for effects. My question is: how do I have the guitar's pickups send the sound to the raspberry pi, and then have the raspberry pi send the processed sound to the output jack. If possible, I would like for me to be able to also play guitar while the raspberry pi is powered off. Thank you.

[mth5044]

Are you asking how to make an analog to digital converter, or asking how to do the wiring?

[Jdansti]

Welcome!

I assume you're saying that you'd have onboard effects and not that the onboard Raspberry would control effects on the floor.  I'm not a digital guy, but my understanding is that the microprocessor would control the effects that you'd route the guitar signal through. The guitar signal doesn't go directly though the microprocessor, it goes through other circuitry that is controlled by the microprocessor (I could be wrong, but that's my understanding).  Depending on the size of the hole you make in your guitar, you might need to use smd technology as through hole might be too large. It just depends on what you choose for your effects.  You can have a bypass switch that routes the signal around your effects and straight to the guitar's output jack.  If you let us know what types of effects you're interested in, the digital gurus can point you toward some projects. I hope this makes sense.

[garcho]

the raspberry pi will have some dsp latency. i think people uually use an external sound card. might require even more gear in your guitar. not sure, just sayin'!

have you looked in to Spin FV-1?

keep in mind, the reason fx are not built in most guitars is because
a - no room
b - the point of FX on the floor is that your hands are busy
c - expensive guitar + expensive amp + cheap digital FX =

[vigilante397]

+1 to everything already said. Raspberry Pi is a great platform for an introduction to dsp and embedded systems and is capable of being part of a standalone effects system, but if you don't already know how to hook this up you might want to do some more research before cutting a big hole in your guitar

This would be a good place to start to get familiar with the capabilities of the Raspberry Pi: http://www.instructables.com/id/DIY-Guitar-effect-using-Raspberri-Pi

c - expensive guitar + expensive amp + cheap digital FX =

+100000 to this. If you could create amazingly realistic, low latency digital effects with Raspberry Pi there would be a lot more resources out there, I promise

[Hatredman]

Everything everybody said, specially about cheap digital FX...

That said, did you have the RaspPI already?

Because if you don't mind using an arduino, maybe this would be easyer for you:

http://www.electrosmash.com/pedalshield

[Transmogrifox]

I have done quite a bit with DSP on the Linux platform using JACK (Jack Audio Connection Kit).  On more of a desktop type of PC you can get latencies less than 1ms with some kernel hacking.  Up until the recent release of the new Pi with significant boost in horsepower I would have said this is a bad idea, but you can probably do pretty well on latency using the new Pi.

AutoStatic (google the name) has done quite a bit with guitar FX on the Pi. 

You will probably want to get an external USB audio interface with higher quality A/D and D/A conversion than the audio interfaces built into the Pi.  If space is an issue, then cannibalize the PCB and wire in direct.  I think these are acceptable USB audio interfaces:
http://www.music-group.com/Categories/Behringer/Computer-Audio/Audio-Interfaces/UCG102/p/P0198

I have played live using a laptop as a DSP engine and I have no complaints.

As for being able to play guitar when the Pi is offline I would suggest using a DPDT relay to bypass the whole thing in the non-energized state.  Drive the relay coil from one of the GPIO on the Pi when everything is booted and active.  That way when no power is applied the default condition on the relay is bypass mode, and you don't activate the DSP path until all systems are GO.  Then you always have sound coming out of the guitar.

You could do some really neat stuff with a Pi onboard.  If you have a WiFi dongle on it you could present a control surface over the local network that you could control with an iPad or laptop, or whatever.  Your grandma could be controlling your FX from 100 miles away...maybe you don't want that but you get the idea.

I don't know what your level of experience is with this stuff -- do you have programming experience, do you know anything about Linux?  Don't even consider Windows 10 on the new Pi -- you'll never get acceptable latency with Windows not to mention you won't have any resources left over to do any real DSP.  And you miss out on most of the free software.  PureData is a popular application for this although I have never done it.

I write most of my own DSP in C so something like PD didn't hook me because it looked like yet another learning curve to climb.

[rotylee]

many avenues to achieve sounds. how effective "?"
http://www.diystompboxes.com/smfforum/index.php?topic=111327.0