Classic Amp Revived With A Pi

Guitar amplifiers have a hard life, and as anyone who’s run a venue can tell you, they often have significant electrical issues after a life on the road. [Dsagman] had a Vox amplifier with fried internals, and rather than repair the original he rebuilt it with a Raspberry Pi inside to provide a fully-loaded array of effects.

Though the subject is the Vox, it’s best to see this as more a tale of how to create a guitar effect array in a Pi than specifically put it in an amplifier. The Pi has an audio board and an MCP3008 ADC added to it, and using those two it takes its inputs from a series of potentiometers and process the audio passing through the audio board. In addition there are a series of LED indicators and an LED bar graph to keep the user in touch with what’s going on.

The whole lot is nicely integrated in the VOX case with all the potentiometers on an aluminium panel. He discusses amplifier choice, but as you might expect the final choice is a Class D module. All in all an amp many readers would probably go for.

As long-time readers will remember, guitar effects have made quite a few appearances around here. Continue reading “Classic Amp Revived With A Pi”

MIDI Controller Looks Good, Enables Your Air Guitar Habit

We all want to be guitar heroes, but most of us have to settle for letting a MIDI board play our riffs using a MIDI controller. [Joris] thinks a MIDI controller should look like a cool instrument and thus the Ni28 was born. Honestly, we first thought we were looking at wall art, but on closer look, you can see the fretboard and the soundhole are festooned with buttons.

Actually, they aren’t really buttons. The Ni in the name is because the buttons are nickel-plated brass plates that act like touch switches. There’s virtually no activation force required and you can easily touch more than one plate at a time.

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Balloon Guitar Is An Absolute Gas, Helium Or Not

Guitars are most typically built out of wood. Whether it’s an acoustic guitar with a big open cavity, or a solid-body electric, there’s generally a whole lot of wood used in the construction. However, [Mattias Krantz] shows us that alternative construction methods are entirely possible, by building his own balloon guitar.

The balloon guitar still has a neck, bridge, and strings just like any other. However, in place of the resonant cavity of an acoustic guitar, there is provision to install a large balloon instead. It’s actually quite interesting to watch — with the balloon installed, the guitar delivers much more volume than when played without a resonant cavity at all.

The guitar was actually built to test if swapping out air in the balloon for helium would shift the pitch of the sound. Of course, a guitar’s pitch comes from the tension on the vibrating strings, so changing the gas in the resonant cavity doesn’t directly affect it. Instead, much like inhaling helium to affect the human voice, the change is to the timbre of the sound, not the fundamental pitch itself. It sounds as if the guitar has been given a subtle treble boost.

It’s a fun build, and one that shows us that it’s possible to build musical instruments in many ways, not just using traditional techniques. If you want to further play with your guitar’s sound, though, consider turning to the world of machine learning.

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Processing Audio With The RP2040

The Raspberry Pi, although first intended as an inexpensive single-board computer for use in education, is now ubiquitous in electronics communities. Its low price as well as Linux platform and accessible GPIO make it useful in many places outside the classroom. But, if you want to abandon the ease-of-use in favor of an even lower price, the Raspberry Pi foundation makes that possible as well with the RP2040 chip, commonly found on the Pico. [Jason] shows us one way to make use of this powerful chip by putting one in an audio digital signal processing board.

While development boards are available for this chip, [Jason] has opted instead for a custom PCB which he designed himself and includes an integrated headphone amplifier and 3.5 mm audio jacks. To do the actual DSP work, the RP2040 chip uses three 12-bit ADC channels and 16 controllable PWM channels. The platform is also equipped with the TLV320AIC3254 codec from Texas Instruments. With all of this put together, he has a functioning open-source platform he calls the DS-Pi.

[Jason] has built this as a platform for guitar effects and as a customizable guitar amp modeler, but with a platform that is Arduino-compatible and fairly easy to program it could be put to use for anything involving other types of music or audio processing, like this specialized MIDI-compatible guitar effects platform which is built around the same processor.

3D Printing A Guitar Neck

A lot of first-time guitar builders focus on making the body and skip the neck, which has lots of tricky dimensions to get right to if you want a nicely playable instrument. However, [Jón Schone] of Proper Printing wanted to start with the hard part on his guitar building journey, and set about 3D printing a guitar neck in one piece.

Designing a neck might sound difficult on the surface of it, but the Marz Guitar Designer plugin for FreeCAD helps make whipping one up a cinch. Once imported into Fusion 360, the geometry is tweaked for 3D printing, particularly to fit the truss rod inside. Printed on a Creality CF30 belt printer (which interestingly enough, has been mounted to the wall) in green PLA, the resulting neck can be spotted as a non-traditional design from a mile away. With a truss rod hammered in, frets installed, and hardware attached, it’s mounted up to a cheap kit guitar for testing.

The printed neck works, and it’s given a proper shakedown with some appropriate riffs to put it through its paces. It’s reportedly a bit on the flexible side, but remains playable and is surprisingly normal in its performance. [Jón] now plans to continue the project by 3D printing the rest of the guitar.

Meanwhile, if you’re sick of tuning your own guitar, consider building a robot tuner to help out. Video after the break.

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Learn To Play Guitar, Digitally

Learning to play a musical instrument takes a major time commitment. If you happened to be stuck inside your home at any point in the last two years, though, you may have had the opportunity that [Dmitriy] had to pick up a guitar and learn to play. Rather than stick with a traditional guitar, though, [Dmitriy] opted to build his own digital guitar which is packed with all kinds of features you won’t find in any Fender or Gibson.

The physical body of this unique instrument is entirely designed by [Dmitriy] out of 3D printed parts, and uses capacitive touch sensors for each of the notes on what would have been the guitar’s fretboard. The strings are also replaced with a set of six switches that can be strummed like a regular guitar, and are used to register when to play a note. After a few prototypes, everything was wired onto a custom PCB. The software side of this project is impressive as well; it involved creating custom firmware to register all of the button presses and transmit the information to a MIDI controller so that the guitar can communicate digitally with anything that supports MIDI.

To finish off the project, [Dmitriy] also added a wireless device as well as some other bonus features like an accelerometer, which can be used to augment the sound of the guitar in any way he can think of to program them. It’s one of the most innovative guitars we’ve seen since the prototype Noli smart guitar was unveiled last year, and this one is also on its way from prototype to market right now.

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Travel Guitar Hacked With Digital FX Setup

[Courcirc8] was a big fan of the ALP AD-80, with the travel guitar being a surprisingly competent instrument despite its folding form-factor. However, the onboard headphone amp left something to be desired, so it was time to get hacking.

To achieve better audio output, [courcirc8] decided to purchase an iRig HD 2 guitar interface, and installed it inside the body of the compact guitar. The original volume pot on the guitar was instead spliced into the iRig circuit, and a switch hooked up to allow the guitar to output clean tones to an amp or the digital audio output of the iRig instead. It’s a tight fit inside, but it all nestles in there rather neatly when finished.

The result is a compact guitar that has a capable digital FX platform built in to the body; all one has to do is hook up a smartphone to gain access to a broad selection of software effects.  It makes the guitar much more of a Swiss Army knife when playing on the road.

We’ve seen others before installing guitar effects into the instrument itself; it remains perhaps one of the best ways a hacker can express themselves with a completely individual instrument!