Four Steppers Make A Four-Voice MIDI Instrument

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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Forgotten Rock Band Drum Controller As A MIDI Instrument

Happen to have an old Rock Band drum controller collecting dust in your living room? If you also have a spare Arduino and don’t mind parting with that plastic college memento then you’ve got the bulk of what could potentially be your new percussive MIDI instrument. In his project video [Evan Kale] outlines the steps necessary to turn that unloved plastic into a capable instrument for recording.

The whole process as outlined by [Evan] in under seven minutes. This looks like a great weekend endeavor for those of us just starting out with MIDI. After cracking the back of the Guitar Hero drum kit controller open, the main board within is easily replaced with a standard sized Ardunio (which matches the present mounting holes exactly). About 4:50 into the video [Evan] explains how to add a basic perf-board shield over the Arduino which connects the piezo sensors in each of the drum pads to the analog pins of the micro-controller. The MIDI jack that comes built into the back of the kit can also be reused as MIDI out when wired to the Arduino’s serial out pin. By adjusting [Evan’s] example code you can dial in the instrument’s feedback to match the intensity of each hit.

The video with all of the details is after the jump. Or you can check out a MIDI hack that goes the other way and uses a drum kit as a Guitar Hero or Rock Band controller instead

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Guitar Hero As An Instrument Or Midi Controller

[Robert] wrote a program using Max/MSP that lets him make music with his guitar hero controller. There’s another video after the break where he walks through the various features but here’s the gist of it. This works on Mac and Windows and allows a sort of ‘live play’ or midi mapping mode. In the midi mode each key can be configured to do your bidding. His example uses the pick bar to scroll through different samples and the green button the play them or the red button to stop.

The live mode us much more involved. In the software you choose the type of scale and the key you’d like to play in. This makes up for the controller’s lack of enough frets to make it a chromatic instrument and these settings can be adjust from the controller. There is an up-pick offset that makes the upward movement of the pick bar a different note than the downward movement. The motion control can also be used as an input. He demonstrates pitch bending and cutoff using that method.

This looks like a lot of fun. He needs to team up with [Joran] to add drums to the mix, forming a much more creative rock band than you can buy in the store.

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Guitar Pickguard Adds MIDI Capabilities

For a standard that has been in use since the 1980s, MIDI is still one of the most dominant forces on the musical scene even today. It’s fast, flexible, and offers a standard recognized industry-wide over many different types of electronic instruments. Even things which aren’t instruments can be turned into musical devices like the infamous banana keyboard via the magic of MIDI, and it also allows augmentation of standard instruments with other capabilities like this guitar with a MIDI interface built into the pick guard.

[Ezra] is the creator of this unique musical instrument which adds quite a few capabilities to his guitar. The setup is fairly straightforward: twelve wires run to the pick guard which are set up as capacitive sensors and correspond with a note on the chromatic scale. Instead of using touchpads, using wires allows him to bend away the “notes” that he doesn’t need for any particular piece of music. The wires are tied back to an Adafruit Feather 32u4 microcontroller behind the neck of the guitar which also has a few selectors for changing the way that the device creates tones. He can set the interface to emit single notes or continuously play notes, change the style, can change their octave, and plenty of other features as well.

One of the goals of this project was to increase a guitar player’s versatility when doing live performances, and we would have to agree that this gives a musician a much wider range of abilities without otherwise needing a lot of complex or expensive equipment on stage. We’ve seen a few other MIDI-based builds focused on live performances lately, too, like this one which allows a band to stay in sync with each other.

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This is a MIDI harp that is played by waving your hands in the air over the infrared distance sensors.

Teensy MIDI Air Harp Sounds Huge

Some of the coolest sounds come from wild instruments like orchestra strings, fretless basses, and theremins — instruments that aren’t tied down by the constraints of frets and other kinds of note boundaries. [XenonJohn]’s air harp is definitely among this class of music makers, all of which require a certain level of manual finesse to play well.

Although inspired by Jean-Michel Jarre’s laser harp, there are no lasers here. This is a MIDI aetherharp, aka an air harp, and it is played by interrupting the signals from a set of eight infrared distance sensors. These sensors can be played at three different heights for a total of 24 notes, plus there’s a little joystick for doing pitch bends.

Inside the wooden enclosure of this aetherharp is a Teensy 3.5 and eight infrared distance sensors with particularly long ranges. On top is a layer of red acrylic that doesn’t affect the playability, except in bright sunlight. Although you could use most any MIDI software to produce the actual sounds, [XenonJohn] chose VMPK (Virtual MIDI Piano Keyboard). Be sure to check it out in action after the break.

Not dangerous enough for you? Here’s a laser harp that involves a Tesla coil.

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MIDI Mouse Makes Marvelous Music

It’s an old misconception that digital musicians just use a mouse and keyboard for their art. This is often far from the truth, as many computer music artists have a wide variety of keyboards/synths, MIDI controllers, and “analog” instruments that all get used in their creative process. But what if one of those instruments was just a mouse?

Well, that must have been what was going through [kzra]’s mind when he turned an old ps/2 roller ball mouse into an electronic instrument. Born out of a love for music and a hate for waste, the mouse is a fully functional MIDI controller. Note pitch is mapped to the x-coordinate of the pointer, and volume (known as velocity, in MIDI-speak) is mapped to the y-coordinate. The scroll wheel can be used as a mod wheel, user-configurable but most often used to vary the note’s pitch. The mouse buttons are used to play notes, and can behave slightly differently depending on the mode the instrument is set to.

Not satisfied with simply outputting MIDI notes, [kzra] also designed an intuitive user interface to go along with the mouse. A nice little OLED displays the mode, volume, note, and mouse coordinates, and an 8×8 LED matrix also indicates the note and volume. It’s a fantastic and versatile little instrument, and you’ve gotta check out the video after the break to see it for yourself. We’ve seen some awesome retro-tech MIDI controllers before, and this fits right in.

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MIT’s Knitted Keyboard Is Quite A Flexible MIDI Controller

There are only so many ways to make noise on standard instruments such as acoustic pianos. Their rigidity and inputs just don’t allow for a super-wide range of expression. On the other hand, if you knit your interface together, the possibilities are nearly endless. MIT’s new and improved knitted keyboard is an instrument like none other — it responds to touch, pressure, and continuous proximity, meaning that you can play it like a keyboard, a theremin, and something that is somewhere in between the two. Because it’s a MIDI interface, it can ultimately sound like any instrument you’ve got available in software.

The silver keys of this five-octave interface are made of conductive yarn, and the blue background is regular polyester yarn. Underneath that is a conductive knit layer to complete the key circuits, and a piezo-resistive knit layer that responds to pressure and stretch. It runs on a Teensy 4.0 and uses five MPR121 proximity/touch controllers, one per octave.

The really exciting thing about this keyboard is its musical (and physical) versatility. As you might expect, the keyboard takes discrete inputs from keystrokes, but it also takes continuous input from hovering and waving via the proximity sensors, and goes even further by taking physical input from squeezing, pulling, stretching, and twisting the conductive yarns that make up the keys. This means it takes aftertouch (pressure applied after initial contact) into account —  something that isn’t possible with most regular instruments. And since this keyboard is mostly yarn and fabric, you can roll it up and take it anywhere, or wrap it around your neck for a varied soundscape.

If you’re looking for more detail, check out the paper for the previous version (PDF), which also used thermochromic yarn to show different colors for various modes of play using a heating element. With the new version, [Irmandy Wicaksono] and team sought to improve the sensing modalities, knitted aesthetics, and the overall tactility of the keyboard. We love both versions! Be sure to check it out after the break.

Want to play around with capacitive touch sensors without leaving the house for parts? Make your own from paper and aluminum foil.

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