midi

375 Articles

Digital Guitar Of The Future Has No Strings

August 1, 2025 by 16 Comments

Electric guitars are great, but they’re just so 20th century. You’d think decades of musicians riffing on the instrument would mean there are no hacks left in the humble axe. You’d think so, but you’d be wrong. [Michael], for one, has taken it upon himself to reinvent the electric guitar for the digital era.

Gone are the strings, and the frets have vanished as well. The neck of this guitar is one long custom PCB, looking very sleek with black solder mask. Gold pads serve as touch sensors to give tone data over i2c (from unspecified touch sensing chips) to the Amtel Mega 32u4 at the heart of the build.

With no strings, strumming won’t work, so a laptop-style touchpad serves instead. That means every user interaction with this guitar is with capacitive touch sensors talking i2c. The X and Y coordinates of the touch, along with pressure are sent to the processor over the i2c bus, triggering an interrupt and offering quite a bit of opportunity for sound control.

Said sound control is, of course, done in MIDI. This lets the guitar control a whole variety of synths and/or software, and of course [Michael] is using more futuristic-sounding synths than a pack of guitar samples. That said, what exactly goes on with the MIDI controls is left frustratingly vague. Obviously fretting provides note selection, but does the touchpad just send a “note start” command, or are the X, Y and pressure data used in interesting ways? Is there multitouch support? The video doesn’t say.

How, exactly, the obviously-plastic body of the guitar was manufactured is also left unsaid. Is it a large resin print? SLS? It looks injection-molded, but that makes no sense for a one-off prototype. On the other hand, it looks like he’s selling these, so it may very well be an injection-molded production case we’re seeing being assembled here, and not a prototype at all.

For all the video leaves us wanting more information, we can’t help but admit the end product both looks and sounds very cool. (Skip to the 4:50 mark in the embedded video to hear it in action.) The only thing that would improve it would be a hurdy-gurdy mode. Thanks to [Michael] for the tip, and remember  we want to hear tips about all the weird and wonderful hacked-together instruments you make or find on the web.

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OpenMIDIStomper Makes Sure Your Gear Does What Your Foot Says

July 3, 2025 by 1 Comment

If you’re a solo musician, you probably have lots of gear you’d like to control, but you don’t have enough hands. You can enlist your feet, but your gear might not have foot-suitable interfaces as standard. For situations like these, [Nerd Musician] created the OpenMIDIStomper.

The concept is simple enough—the hardy Hammond enclosure contains a bunch of foot switches and ports for external expression pedals. These are all read by an Arduino Pro Micro, which is responsible for turning these inputs into distinct MIDI outputs to control outboard gear or software. It handles this via MIDI over USB. The MIDI commands sent for each button can be configured via a webpage. Once you’ve defined all the messages you want to send, you can export your configuration from the webpage by cutting and pasting it into the Arduino IDE and flashing it to the device itself.

We’ve featured some great MIDI controllers over the years, like this impressive parts bin build.

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A black PCB is shown, with an Arduino Nano mounted in the bottom left corner. The rest of the space on the PCB is used up by ten DIP integrated circuits and a few resistors and diodes. Several black and red wires connect different parts of the PCB.

Meowsic Keyboard MIDI Adapter Aims For Purrfection

June 14, 2025 by 3 Comments

Both small children and cats have a certain tendency to make loud noises at inopportune times, but what if there were a way to combine these auditory effects? This seems to have been the reasoning behind the creation of the Meowsic keyboard, a children’s keyboard that renders notes as cats’ meows. [Steve Gilissen], an appreciator of unusual electronic instruments, discovered that while there had been projects that turned the Meowsic keyboard into a MIDI output device, no one had yet added MIDI input to it, which of course spurred the creation of his Meowsic MIDI adapter.

The switches in the keys of the original keyboard form a matrix of rows and columns, so that creating a connection between a particular row and column plays a certain note. [Steve]’s plan was to have a microcontroller read MIDI input, then connect the appropriate row and column to play the desired note. The first step was to use a small length of wire to connect rows and columns, thus manually mapping connections to notes. After this tedious step, he designed a PCB that hosts an Arduino Nano to accept input, two MCP23017 GPIO expanders to give it enough outputs, and CD4066BE CMOS switches to trigger the connections.
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When Wireless MIDI Has Latency, A Hardwired Solution Saves The Day

June 7, 2025 by 14 Comments

[Moby Pixel] wanted to build a fun MIDI controller. In the end, he didn’t build it just once, but twice—with the aim of finding out which microcontroller was most fit for this musical purpose. Pitted against each other? The ESP32 and Raspberry Pi Pico.

The MIDI controller itself is quite fetching. It’s built with a 4 x 4 array of arcade buttons to act as triggers for MIDI notes or events. They’re assembled in a nice wooden case with a lovely graphic wrap on it. The buttons themselves are wired to a microcontroller, which is then responsible for sending MIDI data to other devices.

At this point, the project diverges. Originally, [Moby Pixel] set the device up to work with an ESP32 using wireless MIDI over Bluetooth. However, he soon found a problem. Musical performance is all about timing, and the ESP32 setup was struggling with intermittent latency spikes that would ruin the performance. Enter the Raspberry Pi Pico using MIDI over USB. The hardwired solution eliminated the latency problems and made the controller far more satisfying to use.

There may be solutions to the latency issue with the wireless ESP32 setup, be they in code, hardware configuration, or otherwise. But if you want to play with the most accuracy and the minimum fuss, you’ll probably prefer the hardwired setup.

Latency is a vibe killer in music as we’ve explored previously.

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It’s MIDI For The TRS-80!

June 1, 2025 by 16 Comments

The Radio Shack TRS-80 was a much-loved machine across America. However, one thing it lacked was MIDI. That’s not so strange given the era it was released in, of course. Nevertheless, [Michael Wessel] has seen fit to correct this by creating the MIDI/80—a soundcard and MIDI interface for this old-school beast.

The core of the build is a BluePill STM32F103C8T6 microcontroller, running at a mighty 75 MHz. Plugged into the TRS-80s expansion port, the microcontroller is responsible for talking to the computer and translating incoming and outgoing MIDI signals as needed. Naturally, you can equip it with full-size classic DIN sockets for MIDI IN and MIDI OUT using an Adafruit breakout module. None of that MIDI Thru nonsense, though, that just makes people uncomfortable. The card is fully capable of reproducing General MIDI sounds, too, either via plugging in a Waveblaster sound module to the relevant header, or by hooking up a Roland Sound Canvas or similar to the MIDI/80s MIDI Out socket. Software-wise, there’s already a whole MIDI ecosystem developing around this new hardware. There’s a TRS-80 drum tracker and a synthesizer program, all with demo songs included. Compatibility wise, The MIDI/80 works with the TRS-80 Model I, III, and 4.

Does this mean the TRS-80 will become a new darling of the tracker and chiptune communities? We can only hope so! Meanwhile, if you want more background on this famous machine, we’ve looked into that, too. Video after the break.

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Zen Flute Is A Teensy Powered Mouth Theremin

May 17, 2025 by 13 Comments

An intriguing mouth-played instrument emerged—and won—at the 2023 Guthman Musical Instrument Contest hosted by Georgia Tech. [Keith Baxter] took notice and reproduced the idea for others to explore. The result is the Zen Flute Mouth Theremin, a hybrid of acoustics, electronics, and expressive performance.

At its core lies a forced Helmholtz resonator, a feedback system built with a simple microphone and speaker setup. The resonator itself? The user’s mouth. The resulting pitch, shaped by subtle jaw and tongue movements, is detected and used to drive a MIDI controller feeding an external synthesizer.

Like a trombone or classic electromagnetic theremin, the Zen Flute doesn’t rely on discrete notes. Instead, the pitch is bent manually to the desired frequency. That’s great for expression, but traditional MIDI quantisation can map those “in-between” notes to unexpected semitones. The solution? MIDI Polyphonic Expression (MPE). This newer MIDI extension allows smooth pitch transitions and nuanced control, giving the Zen Flute its expressive character without the hiccups.

Physically, it’s an elegant build. A flat speaker and microphone sit side-by-side at the mouth end, acoustically isolated with a custom silicone insert. This assembly connects to a length of clear PVC pipe, flared slightly to resemble a wind instrument. Inside, a custom PCB (schematic here) hosts a mic preamp, an audio power amp, and a Teensy 4.1. The Teensy handles everything: sampling the mic input, generating a 90-degree phase shift, and feeding it back to the speaker to maintain resonance. It also detects the resonant frequency and translates it to MPE over USB.  A push-button triggers note onset, while a joystick adjusts timbre and selects modes. Different instrument profiles can be pre-programmed and toggled with a joystick click, each mapped to separate MIDI channels.

Mouth-controlled instruments are a fascinating corner of experimental interfaces. They remind us of this Hackaday Prize entry from 2018, this wind-MIDI hybrid controller, and, of course, a classic final project from the Cornell ECE4760 course, a four-voice theremin controlled by IR sensors.

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Laser Harp Sets The Tone

March 20, 2025 by 16 Comments

In many ways, living here in the future is quite exiting. We have access to the world’s information instantaneously and can get plenty of exciting tools and hardware delivered to our homes in ways that people in the past with only a Sears catalog could only dream of. Lasers are of course among the exciting hardware available, which can be purchased with extremely high power levels. Provided the proper safety precautions are taken, that can lead to some interesting builds like this laser harp which uses a 3W laser for its strings.

[Cybercraftics]’ musical instrument is using a single laser to generate seven harp strings, using a fast stepper motor to rotate a mirror to precise locations, generating the effect via persistence of vision. Although he originally planned to use one Arduino for this project, the precise timing needed to keep the strings in the right place was getting corrupted by adding MIDI and the other musical parts to the project, so he split those out to a second Arduino.

Although his first prototype worked, he did have to experiment with the sensors used to detect his hand position on the instrument quite a bit before getting good results. This is where the higher power laser came into play, as the lower-powered ones weren’t quite bright enough. He also uses a pair of white gloves which help illuminate a blocked laser. With most of the issues ironed out, [Cybercraftics] notes that there’s room for improvement but still has a working instrument that seems like a blast to play. If you’re still stuck in the past without easy access to lasers, though, it’s worth noting that there are plenty of other ways to build futuristic instruments as well.

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