midi

376 Articles

Four Steppers Make A Four-Voice MIDI Instrument

August 15, 2020 by 17 Comments

Any owner of a budget 3D printer will tell you that they can be pretty noisy devices, due to their combinations of stepper motors and drives chosen for cost rather than quiet. But what if the noise were an asset, could the annoying stepper sound be used as a musical instrument? It’s a question [David Scholten] has answered with the Stepper Synth, a device that takes an Arduino Uno and four stepper motors to create a four-voice MIDI synthesiser.

Hardware-wise it’s as simple as you’d expect, a box with four stepper motors each with a red 3D-printed flag on its shaft to show rotation. Underneath there is the Arduino, plus a robot control shield and a set of stepper driver boards. On the software side it uses MIDI-over-serial, so as a Windows user his instructions for the host are for that operating system only. The Arduino makes use of the Arduino MIDI library, and he shares tips on disabling the unused motors to stop overheating.

You can hear it in action in the video below the break, and we’re surprised to say it doesn’t sound too bad. There’s something almost reminiscent of a church organ in there somewhere, it would be interesting to refine it with an acoustic enclosure of some kind.

This isn’t the first such instrument we’ve brought you, for a particularly impressive example take a look at the Floppotron.

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The Game Boy As A Midi Synthesiser

August 5, 2020 by 6 Comments

In the world of chiptune music there are many platforms to choose from, each with their own special flavour tot heir sound. The Game Boy has a particular following, but it differs from some of its contemporary platforms in having a custom sound chip built into the same silicon as its processor. You can’t crank open a Game Boy and lift out the sound chip for your own synth project, instead you must talk to it through the Game Boy’s Z80 processor. This is something [Adil Soubki] knows well, as he’s completed a project that turns the handheld console into a MIDI synthesiser.

A Game Boy was designed to play games and not as a developer’s toy, so it doesn’t exactly roll out the red carpet for the hacker. He’s got under the console’s skin by mapping a section of its memory address map to the pins on a Teensy microcontroller board, and running some Game Boy code that reads the vaues there and uses them to configure the sound hardware. The Teensy handles the translation between MIDI and these byte values, turning the whole into a MIDI synthesiser. It’s a succesful technique, as can be seen in the video below the break. Best of all, the code is available, so you can have a go for yourself.

We’ve featured Game Boy synths before here at Hackaday, but usually they have been of the more conventional variety.

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Your Own Electronic Drum Kit

July 8, 2020 by 6 Comments

[Jake_Of_All_Trades] wanted to take up a new drumming hobby, but he didn’t want to punish his neighbors in the process. He started considering an electric drum kit which would allow him to practice silently but still get some semblance of the real drumming experience.

Unfortunately, electric drum kits are pretty expensive compared to their acoustic counterparts, so buying an electric kit was a bit out of the question. So, like any good hacker, he decided to make his own.

He found a pretty cheap acoustic drum kit on Craigslist and decided to convert it to electric. He thought this would be a perfect opportunity to learn more about electric drum kits in general and would allow him to do as much tweaking as he wanted to in order to personalize his experience. He also figured this would be a great way to get the best of both worlds. He could get an electric kit to practice whenever he wanted without disturbing neighbors and he could easily convert back to acoustic when needed.

First, he had to do a bit of restorative work with the cheap acoustic kit he found on eBay since it was pretty worn. Then, he decided to convert the drum heads to electric using two-ply mesh drum heads made from heavy-duty fiberglass screen mesh. The fiberglass screen mesh was cheap and easy to replace in the event he needed to make repairs. He added drum and cymbal triggers with his own DIY mechanism using a piezoelectric element, similar to another hack we’ve seen. These little sensors are great for converting mechanical to electrical energy and can feed directly into a GPIO to detect when the drum or cymbal was struck. The electrical signal is then interpreted by an on-board signal processing module.

All he needed were some headphones or a small amplifier and he was good to go! Cool hack [Jake_Of_All_Trades]!

While you’re here, check out some of our best DIY musical projects over the years.

A Baby Grand Gets MIDI

June 25, 2020 by 10 Comments

Like a lot of people, [Jacques] doesn’t think a big hunk of plastic light enough to carry under your arm is a piano, even if it does have 88 keys. A piano is supposed to be a hefty piece of furniture that you have to buy people pizza to help you move. So he bought a used baby grand piano. It wasn’t in very good shape, though, so while restoring it, he also added MIDI to it. You can see the finished result in the video below.

At $100, the price was right, although it cost more to move it. Between water damage, moth attacks, and storage in a garage, the piano — an old Zimmerman — needed a lot of tender loving care. When it came to MIDI, [Jacques] found a used Disklavier — a very expensive piece of kit — but it didn’t fit the Zimmerman or another piano at hand. The solenoids and optical sensors are set up for a particular piano, so what can you do? Easy! Rebuild the bar that holds the solenoids and sensors.

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Wurlitzer Note Visualizer Gets A 2020-Spec Replica

June 20, 2020 by 1 Comment

Way back in the 1970s, when smog laws were choking American V8s and the oil crisis was in full swing, Wurlitzer released their Key Note Visualizer. Intended as a teaching aid, the device lit up keys on a keyboard graphic, allowing an organ player to visually demonstrate their performance to a class. [Guy Dupont] set out to replicate this hardware, but with a modern twist.

The build consists of an ESP-32, which accepts MIDI data over Bluetooth Low Energy. This is then used to light up a series of RGB LEDs on a musical staff and a keyboard graphic, corresponding to the notes being played. The LEDs used are the old-school four-wire type, rather than more modern data-driven types. They’re placed in 3D-printed holders which serve to stop the light from each LED bleeding into adjacent areas. The faceplate is made of acrylic, stencilled with that classic orange paint and with vinyl decals applied for the markings. It’s all wrapped up in a walnut case, which [Guy] CNC machined himself.

It’s a tidy build that faithfully recreates the 1970s aesthetic of the original. We plaintively wish that manufacturers would release more electronics in walnut enclosures, though ask politely that they leave cheap veneer in the past where it belongs.

Of course, if you like your musical displays more abstract than instructional, try this giant oscilloscope visualisation on for size. Video after the break.

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Less Rock, More Roll: A MIDI Barrel Piano

June 18, 2020 by 5 Comments

Strolling around a park, pedestrian zone, or tourist area in any bigger city is rarely complete without encountering the sound of a barrel organ — the perfect instrument if arm stamina and steady rotation speed are your kind of musical skills. Its less-encountered cousin, and predecessor of self-playing pianos, is the barrel piano, which follows the same playing principle: a hand-operated crank rotates a barrel, and either pins located on that barrel, or punched paper rolls encode the strings it should pluck in order to play its programmed song. [gabbapeople] thought optocouplers would be the perfect alternative here, and built a MIDI barrel piano with them.

Keeping the classic, hand-operated wheel-cranking, a 3D-printed gear mechanism rolls a paper sheet over a plexiglas fixture, but instead of having holes punched into it, [gabbapeople]’s piano has simple markings printed on them. Those markings are read by a set of Octoliner modules mounted next to each other, connected to an Arduino. The Octoliner itself has eight pairs of IR LEDs and phototransistors arranged in a row, and is normally used to build line-following robots, so reading note markings is certainly a clever alternative use for it.

Each LED/transistor pair represents a dedicated note, and to prevent false positives from neighboring lines, [gabbapeople] 3D printed little collars to isolate each of the pairs. Once the signals are read by the Arduino, they’re turned into MIDI messages to send via USB to a computer running any type of software synthesizer. And if your hands do get tired, you can also crank it with a power drill, as shown in the video after the break, along with a few playback demonstrations.

It’s always fun to see a modern twist added to old-school instruments, especially the ones that aren’t your typical MIDI controllers, like a harp, a full-scale church organ, or of course the magnificently named hurdy-gurdy. And for more of [gabbapeople]’s work, check out his split-flip weather display.

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A 50W Speaker Made Of Light Bulbs

June 8, 2020 by 27 Comments

When we think of a speaker, we are likely to imagine a paper cone with a coil of wire somewhere at the bottom of it suspended in a magnetic field. It’s a hundred-plus-year-old technology that has been nearly perfected. The moving coil is not however the only means of turning an electrical current into a sound. A number of components will make a sound when exposed to audio, including to the surprise of [Eric], the humble incandescent light bulb. He discovered when making an addressable driver for them that he could hear the PWM frequency when they lit up, so he set about harnessing the effect for use as a speaker.

Using an ESP32 board and with a few false starts due to cheap components, he started with MIDI files and ended up with PWM frequencies. It’s an interesting journey into creating multiple PWM channels from an ESP32, and he details some of his problems along the way. The result is the set of singing light bulbs that can be seen in the video below the break, which he freely admits is probably the most awful 50 W speaker that he could have made. That however is not the point of such an experiment, and we applaud him for doing it.

For more MIDI-based tomfoolery, take a look at the PCB Tesla coil.

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