Musical Hacks

1470 Articles

Live Hacking And A MIDI Keytar

March 2, 2019 by 7 Comments

We can’t think of where you’d buy a new, cheap, MIDI keytar that’s just a keyboard and a handle with some pitch and mod wheels or ribbon controllers. This is a format that died in the 90s or thereabouts. Yes, the Rock Band controller exists, but my point stands. In fact, the closest you can get to a cheap, simple MIDI keytar is the Alesis Vortex Wireless 2 Keytar, but the buttons on the handle don’t make any sense. [marcan] of Wii and Kinect hacking fame took note. (YouTube, embedded below.)

Reverse engineering is a research project, and all research projects begin with looking at the docs. When it comes to consumer electronics, the best resource is the documents a company is required to submit to the FCC (shout out to FCC.io), which gave [marcan] the user manual, and photos of the guts of the keytar. The ‘system update download’ files are living on the Alesis servers, and that’s really all you need to reverse engineer a keytar.

The first step is extracting the actual device firmware from whatever software package appears on the desktop when you download the software update. This is a simple job for 7zip, and after looking at a binary dump of the firmware, [marcan] discovered this was for an STM chip. With the datasheet of the chip, [marcan] got the entry point for the firmware, some values, and the real hardware hacking began. All of this was done with IDA.

This is a five-hour hacking session of cross-referencing the MIDI spec and a microcontroller built thirty years after this spec was developed. It’s an amazing bit of work just to find the bit of code than handled the buttons on the keytar grip, and it gets even better when the patched firmware is uploaded. If you want to ‘learn hacking’, as so many submitters on our tip line want to do, this is what you need to watch. Thanks [hmn] for the tip.

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The PC Speaker Lives On As A New Album

February 23, 2019 by 25 Comments

The speaker in the original IBM PC is nearly the worst electronic musical instrument ever created. This isn’t because amazing works of art were never created for the PC speaker; no, that’s been done, and it’s amazing. The PC speaker is terrible because of how limited it is. It does one note at a time, only square waves, driven by an 8253 Programmable Interval Timer. Polyphony? Forget about it. Volume control? Nope. These aren’t really shortcomings, because music is art, and you can write a novel without using the letter ‘E’; the trick is in how you manage to do it.

[shiru8bit] took a deep dive into the PC speaker and decided to make an album. The video, with the completely necessary CRT graphic display, can be seen here. This alone is impressive, but what makes it amazing is how this album happened.

If you want to play more than a simple melody on a PC speaker, there are two or two and a half ways to do it. The first is to (virtually) set up two (or more) channels, loaded up with frequency values. At set intervals, the CPU changes the 8253 to output one frequency, then in the next chunk of time, sets the 8253 to another frequency. It sounds ‘bubbly’ for lack of a better term, but the results can be amazing; just check out the PC speaker version of Monkey Island. The 8253 can also be turned into a rudimentary DAC, but this was a rare technique thanks to patents, and by the time the patents expired everyone already had a Soundblaster. Oh well.

[shiru8bit]’s album uses the first technique, cycling through monophonic square waves at 120 Hz, but the real trick here is how the individual channels were composed. This required creating a VSTi plugin called PCSPE. This emulates a PC speaker, and sort of, kind of, implements arpeggios, pitch, and priority of different channels. Effectively, it’s a PC Speaker tracker.

The result is classic chiptune goodness, made on an instrument that really shouldn’t be used for music. It can be played on DosBox, but the weirdness of the real hardware including transients and the inefficiencies of a tiny speaker make real hardware almost a necessity here. You can check out the entire album below.

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Eurorack Gets A Wireless MIDI Connection

February 21, 2019 by 4 Comments

Modular synthesizers have been around since the early 1960s, delivering huge tonal possibilities from their impressive and imposing patchbays. In 1996, the Eurorack standard was launched, and has become the go-to choice for enthusiasts new to the world of modular synthesis. [Rich Heslip] is just one such enthusiast, and has brought Bluetooth MIDI to Eurorack with his Motivation Radio module.

[Rich]’s module is built around the ESP32, which provides plenty of processing power, along with all the necessary radio hardware to communicate over Bluetooth. The unit packs plenty of connectivity into an 8HP wide panel, with four gate inputs and outputs, four CV inputs and outputs, and serial MIDI in and out.

Thanks to its Bluetooth connection, Motivation Radio makes it easy to pass note and gate data into a Eurorack setup, and can be used with the wide variety of tablet and smartphone MIDI software on offer. If you’re eager to build your own, PCB and panel designs are available courtesy of [jakplugg] and [Rich] has shared the software on Github.

Of course, if you prefer MIDI over USB, [little-scale] has the build for you. Video after the break.

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You Are Your Own Tactile Feedback

February 15, 2019 by 1 Comment

[Maurin Donneaud] has clearly put a lot of work into making a large flexible touch sensitive cloth, providing a clean and intuitive interface, and putting it out there for anyone to integrate into their own project.. This pressure sensing fabric is touted as an electronic musical interface, but if you only think about controlling music, you are limiting yourself. You could teach AI to land a ‘copter more evenly, detect sparring/larping strikes in armor, protect athletes by integrating it into padding, or measure tension points in your golf swing, just to name a few in sixty seconds’ writers brainstorming. This homemade e-textile measures three dimensions, and you can build it yourself with conductive thread, conductive fabric, and piezoresistive fabric. If you were intimidated by the idea before, there is no longer a reason to hold back.

The idea is not new and we have seen some neat iterations but this one conjures ideas a mile (kilometer) a minute. Watching the wireframe interface reminds us of black-hole simulations in space-time, but these ones are much more terrestrial and responding in real-time. Most importantly they show consistent results when stacks of coins are placed across the surface. Like most others out there, this is a sandwich where the slices of bread are ordinary fabric and piezoresistive material and the cold cuts are conductive strips arranged in a grid. [Maurin] designed a custom PCB which makes a handy adapter between a Teensy and houses a resistor network to know which grid line is getting pressed.

If you don’t need flexible touch surfaces, we can help you there too.

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Laser Light Show Turned Into Graphical Equalizer

February 13, 2019 by 25 Comments

The gold standard for laser light shows during rock concerts is Pink Floyd, with shows famous for visual effects as well as excellent music. Not all of us have the funding necessary to produce such epic tapestries of light and sound, but with a little bit of hardware we can get something close. [James]’s latest project is along these lines: he recently built a laser light graphical equalizer that can be used when his band is playing gigs.

To create the laser lines for the equalizer bands, [James] used a series of mirrors mounted on a spinning shaft. When a laser is projected on the spinning mirrors it creates a line. From there, he needed a way to manage the height of each of the seven lines. He used a series of shrouds with servo motors which can shutter the laser lines to their appropriate height.

The final part of the project came in getting the programming done. The brain of this project is an MSGEQ7 which  takes an audio input signal and splits it into seven frequencies for the equalizer. Each one of the seven frequencies is fed to one of the seven servo-controlled shutters which controls the height of each laser line using an Arduino. This is a great project, and [James] is perhaps well on his way to using lasers for other interesting musical purposes.

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TréPhonos Calls Up History In Houston

February 8, 2019 by 7 Comments

Houston’s historic third ward, aka “The Tre,” is ripe rife with history, and some of that history is digitally preserved and accessible through an art installation in the form of repurposed payphones. We love payphones for obvious reasons and seeing them alive and kicking warms our hearts. Packing them with local history checks even more boxes. Twenty-four people collaborated to rebuild the three phones which can be seen in the video after the break, including three visual artists, three ambassadors, and eighteen residents who put their efforts into making the phones relevant not only to the ward but specifically to the neighborhood. One phone plays sound clips from musicians who lived or still live in the ward, another phone has spoken word stories, and the third has field recordings from significant locations in The Tre.

Each phone is powered by a solar cell and a USB battery pack connected to a Teensy with an audio adapter board, and a 20 watt amplifier. Buttons 1-9 play back recorded messages exclusive to each phone, star will record a message, and zero will play back the user-recorded message. Apps for smart phones are easy for young folks to figure out but the payphones ensure that these time capsules can be appreciated by people of any age, regardless of how tech savvy they are and that is wise as well as attractive. The coin return lever and coin slot also have associated sound clips unlike regular payphones so the artists get extra credit.

Did we say that we love payphones? Yes, yes we did. The very first post on Hackday was for a redbox and that got the ball rolling.

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Well-Loved Toy Turned Into Robotic Glockenspiel

February 4, 2019 by 11 Comments

If there’s a happier word ever imported into the English language than “Glockenspiel”, we’re not sure what it is. And controlling said instrument with a bunch of servos and an Arduino makes us just as happy.

When [Leon van den Beukel] found a toy glockenspiel in a thrift store, he knew what had to be done – Arduinofy it. His first attempt was a single hammer on a pair of gimballed servos, which worked except for the poor sound quality coming from the well-loved toy. The fact that only one note at a time was possible was probably the inspiration for version two, which saw the tone bars removed from the original base, cleaned of their somewhat garish paint, and affixed to a new soundboard. The improved instrument was then outfitted with eight servos, one for each note, each with a 3D-printed arm and wooden mallet. An Arduino runs the servos, and an Android app controls the instrument via Bluetooth, because who doesn’t want to control an electronic glockenspiel with a smartphone app? The video below shows that it works pretty well, even if a few notes need some adjustment. And we don’t even find the servo noise that distracting.

True, we’ve featured somewhat more accomplished robotic glockenspielists before, but this build’s simplicity has a charm of its own.

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