Musical Robot Lets You Play The Recorder Hands-Free

May 29, 2023 by Robin Kearey 6 Comments

Although many people might remember the recorder as just a simple instrument from their introductory music classes, it can nevertheless produce rich and varied melodies in the hands of a virtuoso like Frans Brüggen. [Luis Marx] also took music lessons as a child, but never progressed much beyond an elementary level. Instead, he preferred to spend his time honing his engineering skills, which eventually enabled him to get back into music.

Initially, he wanted to build a piano-playing exoskeleton, to marionette his fingers up and down the ivories, but had to bail on that one because of the insane complexity. So instead, he built himself a robot that helps him play the recorder. (Video, in German, embedded below, fast-forwarded to the recorder part.)

A recorder has eight finger holes, which can be covered or uncovered in various combinations to produce tones. [Luis] therefore used eight solenoids, mounted on a 3D-printed frame, to actuate the finger holes. The basic idea worked, but getting the solenoids to fully cover the holes each time turned out to be a challenge: even a slight misalignment would cause air to leak past the plug and produce a horrible off-key sound.

After a lot of trial and error, [Luis] found foam earplugs to be a pretty good material for emulating human fingertips. He also discovered that relying on the solenoids’ spring tension to keep the holes closed was not reliable; a better solution was to flip the solenoids around and use the much larger force from their powered stroke to create an air-tight seal.

The solenoids are driven by an Arduino Nano through a set of MOSFET modules, powered by a lithium battery. [Luis] wrote some Arduino sketches with famous melodies like Beethoven’s Für Elise, which sound quite decent on the robo-recorder: perhaps not on Frans Brüggen’s level, but pretty impressive for a self-declared “music noob” like [Luis].

Many robotic musicians play instruments like pianos or xylophones. Instruments from the flute family are harder to automate, but it has been done before. We’ve even seen a MIDI-powered harmonica.

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We’ve Got A Saxaboom At Home Son

May 21, 2023 by Matthew Carlson 6 Comments

Most parents have heard a familiar story. Their lovely child comes up, having seen a celebrity rocking out with a funny $20 toy from the 80s, and asks for it. Of course, you reply, it’s just 20 dollars. However, a quick scan through eBay reveals that everyone else’s kid has also been asking for this obscure toy for a school event, which now costs around $700. [Ben] found himself in that exact position and made a crucial off-hand comment, “I bet I could make one of those.” That was how his hectic journey into the world of toy reproduction began.

All [Ben] had for reference when recreating a Sax-A-Boom were pictures and sound clips. Modeling complex sweeping shapes in CAD is difficult, and [Ben] commissioned a 3d model from a professional on Fiverr. [Ben] broke down the model into printable sections and tweaked it to account for buttons. After a concerning amount of putty, wet sanding, and elbow grease, [Ben] had a decently smooth body for an instrument. The device’s guts is an ESP32-based board called Sonatino, built around music generation. The music samples came from a virtual instrument clone on GitHub and loaded onto an SD card.

Time pressure crept in towards the end, and [Ben] had to go for some dirty solution that he would have preferred (popsicle sticks and epoxy for button mounting). Yes, there were some gaps and paint flaws, but ultimately [Ben’s] son rocked the school presentation. It’s a beautiful journey through creating something with a high level of finish on a limited timescale.

Perhaps future versions of the Sax-A-Boom can take it further by adding a breath sensor, like this 3d printed MIDI instrument.

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Building A Breath-Controlled MIDI Device

May 19, 2023 by Lewin Day 6 Comments

When we think of MIDI devices, we typically jump straight to drum machines, rack synths, and keyboard controllers. However, there’s nothing saying you can’t build your own MIDI controllers that use the magic of breath to do their musical duty. That’s precisely what [Xavier Dumont] did with this unique 3D printed build.

The device looks somewhat like an alien ship from an animated 1960s sci-fi movie, but it’s actually a sophisticated MIDI controller. Naturally, it’s peppered with buttons as every good controller should be, and it features a touch-control strip on the back.

However, the real magic is in the breath control. When the user blows into the sensor, the device sends out MIDI signals of varying intensity to control the object of the player’s desire. The breath signal can be used to modulate the mod wheel, pitch bends, or octave shifts, among a variety of other options.

[Xavier] wields the instrument with prowess in the audio demos at the end of the video. We can imagine this futuristic thing being played by a background alien in a celebration scene in a far-flung Marvel movie. Or maybe Star Wars? In any case, a triumph.

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MIDI Interface For NeXTcube Plugs Into The Past

May 16, 2023 by Donald Papp 21 Comments

[Joren] recently did some work as part of an electronic music heritage project, and restored an 80s-era NeXTcube workstation complete with vintage sound card, setting it up with a copy of MAX, a graphical music programming environment. But there was one piece missing: MIDI. [Joren] didn’t let that stop him, and successfully created hardware to allow MIDI input and output.

The new panel provides all the connectors necessary to interface with either classic MIDI devices, or MIDI over USB (where it appears as a USB MIDI device to any modern OS.)

Interestingly, the soundcard for the NeXTcube has an RS-422 serial port and some 8-pin mini DIN connectors. They are not compatible with standard MIDI signals, but they’re not far off, either.

To solve this, [Joren] used a Teensy developer board to act as an interface between classic MIDI devices like keyboards or synthesizers (or even not-so-common ones like this strange instrument) while also being able to accommodate modern MIDI over USB connections thanks to the Teensy’s USB MIDI functionality.

A metal enclosure with a 3D-printed panel rounds out the device, restoring a critical piece of functionality to the electronic music-oriented workstation.

MIDI as a protocol isn’t technically limited to musical applications, though that’s one place it shines. And just in case it comes in handy someday, you can send MIDI over I2C if you really need to.

DIY Programmable Guitar Pedal Rocks The Studio & Stage

May 16, 2023 by Donald Papp 10 Comments

Ever wondered how to approach making your own digital guitar effects pedal? [Steven Hazel] and a friend have done exactly that, using an Adafruit Feather M4 Express board and a Teensy Audio Adapter board together to create a DIY programmable digital unit that looks ready to drop into an enclosure and get put right to work in the studio or on the stage.

The bulk of the work is done with two parts, and can be prototyped easily on a breadboard.

[Steven] also made a custom PCB to mount everything, including all the right connectors, but the device can be up and running with not much more than the two main parts and a breadboard.

On the inside, the Adafruit Feather M4 Express board works with the audio board over I2S, a standard for sending serial digital audio between chips. Working with the audio itself is done with the Teensy Audio Library, providing a fantastic array of easy-to-use functions for processing and manipulating digital audio streams.

Together, all the right pieces are in place and [Steven] provides the code for a simple tremolo effect as a glimpse of what’s possible with the unit. Interested in going a bit further? [Steven] shares additional details about what’s involved in writing a custom effect from scratch using the Teensy Audio Library.

As mentioned, I2S is where it’s at when it comes to working with digital audio at the chip level, and our own Jenny List can tell you everything you need to know about I2S, a useful protocol that has actually been around since 1982!

An RPi-Powered Multi-DX7/TX816 Style Synth

May 7, 2023 by Dave Rowntree 16 Comments

[Kevin] over at Simple DIY ElectroMusic Projects has released a complete DIY modular design for simulating the classic 80s Yamaha TX816 DX/FM modular digital synthesizer. This beast of a synth was used by the cool bands of the 80s as well as TV studios, and ownership of the original machine is an expensive investment. But with the power of modern hackable electronics, and the MiniDexed firmware running bare-metal on a Raspberry Pi getting access to a compatible synth doesn’t have to break the bank.

[Kevin] wanted to emulate the look and feel of the original TX816 aesthetic, developing a custom PCB handling the user interface for four of the eight channels, and a second acting as an interface to the Raspberry Pi using a Pico. Also sitting on this PCB is the GY-PCM5102 I²S DAC, and the MIDI connectors needed to connect to the system controller. Both PCBs, including a PCB-based front panel, were developed with KiCAD. The firmware for the Pico part of the system can be found on the firmware GitHub. The video demo (embedded below) shows off the system running a very 80s-sounding rendition of Holst’s famous ‘Jupiter’ from the planet series, and we all agree it sounds pretty sweet. For a complete rundown of the build, here are the links for the blog series for ease of access: Intro, PCBs, Panel, Build Guide, Mechanical, Pico/TX816 IO code, and finally usage. Phew!

If MiniDexed sounds familiar, that is because we featured another of [Kevin’s] earlier MiniDexed projects a little while ago.

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Messing With A Cassette Player Never Sounded So Good

April 24, 2023 by Donald Papp 8 Comments

Cassette players and tapes are fertile hacking ground. One reason is that their electromechanical and analog nature provides easy ways to fiddle with their operation. For example, slow down the motor and the playback speed changes accordingly. As long as the head is moving across the tape, sound will be produced. The hacking opportunities are nicely demonstrated by [Lara Grant]’s cassette player mod project.

The device piggybacks onto a battery-powered audio cassette player and provides a variety of ways to fiddle with the output, including adjustable echo and delay, and speed control. At the heart of the delay and echo functionality is the PT2399, a part from the late 90s capable of some pretty impressive audio effects (as long as a supporting network of resistors and capacitors are in place, anyway.)

[Lara] provides a schematic for the PT2399’s interface to the cassette player’s output, which is handy should anyone want to try a similar modification. Speed of playback is controlled by adjusting the cassette player’s motor with PWM. Volume control swaps a photocell in place of a rotary volume potentiometer, and additional audio jacks provide flexibility for mixing and matching input and output with other equipment.

You can see it in action in the video embedded below. Intrigued, and want a few more examples of modified tape players? How about a strange sort of cassette synth, or this unique take on a mellotron that uses a whopping 14 modified tape players under the hood? And really out there is the Magnetotron, which consists of a large rotating cylinder with tape loops stuck to it — the magnetic read head is mounted on a wand which the user manually moves across the tapes to create sounds.

Tape players are accessible, hackable things, so remember to drop us a line if you make something neat!

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