Laser Harp Sounds Real Thanks To Karplus-Strong Wave Equation

December 29, 2018 by Dan Maloney 9 Comments

The harp is an ancient instrument, but in its current form, it seems so unwieldy that it’s a wonder that anyone ever learns to play it. It’s one thing to tote a rented trumpet or clarinet home from school to practice, but a concert harp is a real pain to transport safely. The image below is unrelated to the laser harp project, but proves that portable harping is begging for some good hacks.

Concert grand harps are so big there’s special equipment to move them around. This thing’s called the HarpCaddy

Enter this laser harp, another semester project from [Bruce Land]’s microcontroller course at Cornell. By replacing strings with lasers aimed at phototransistors, [Glenna] and [Alex] were able to create a more manageable instrument that can be played in a similar manner. The “strings” are “plucked” with the fingers, which blocks the laser light and creates the notes.

But these aren’t just any old microcontroller-generated sounds. Rather than simply generating a tone or controlling a synthesizer, the PIC32 uses the Karplus-Strong algorithm to model the vibration of a plucked string. The result is very realistic, with all the harmonics you’d expect to hear from a plucked string. [Alex] does a decent job putting the harp through its paces in the video below, and the write-up is top notch too.

Unique musical instruments like laser harps are far from unknown around these parts. We’ve seen a few that look something like a traditional harp and one that needs laser goggle to play safely, but this one actually looks and sounds like the real thing. Continue reading “Laser Harp Sounds Real Thanks To Karplus-Strong Wave Equation” →

A Scratch Instrument For Ants

December 20, 2018 by Bryan Cockfield 2 Comments

If you think that this scratch instrument looks as though it should be at least… three times larger in order to be useful, you’d be wrong. This mighty pocket-sized instrument can really get the club hopping despite its diminuitive size. Despite that, the quality of the build as well as its use of off-the-shelf components for almost every part means that if you need a small, portable turntable there’s finally one you can build on your own.

[rasteri] built the SC1000 digital scratch instrument as a member of the portabilist scene, focusing on downsizing the equipment needed for a proper DJ setup. This instrument uses as Olimex A13-SOM-256 system-on-module, an ARM microprocessor, and can use a USB stick in order to load beats to the system. The scratch wheel itself uses a magnetic rotary encoder to sense position, and the slider is miniaturized as well.

If you want to learn to scratch good and learn to do other things good too, there’s a demo below showing a demonstration of the instrument, as well as a how-to video on the project page. All of the build files and software are open-source, so it won’t be too difficult to get one for yourself as long as you have some experience printing PCBs. If you need the rest of the equipment for a DJ booth, of course that’s also something you can build.

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Musical Mod Lets MRI Scanner Soothe The Frazzled Patient

December 16, 2018 by Dan Maloney 27 Comments

Hackers love to make music with things that aren’t normally considered musical instruments. We’ve all seen floppy drive orchestras, and the musical abilities of a Tesla coil can be ear-shatteringly impressive. Those are all just for fun, though. It would be nice if there were practical applications for making music from normally non-musical devices.

Thanks to a group of engineers at Case Western Reserve University in Cleveland, there is now: a magnetic resonance imaging machine that plays soothing music. And we don’t mean music piped into the MRI suite to distract patients from the notoriously noisy exam. The music is actually being played through the gradient coils of the MRI scanner. We covered the inner working of MRI scanners before and discussed why they’re so darn noisy. The noise basically amounts to Lorenz forces mechanically vibrating the gradient coils in the audio frequency range as the machine shapes the powerful magnetic field around the patient’s body. To turn these ear-hammering noises into music, the researchers converted an MP3 of [Yo Yo Ma] playing [Bach]’s “Cello Suite No. 1” into encoding data for the gradient coils. A low-pass filter keeps anything past 4 kHz from getting to the gradient coils, but that works fine for the cello. The video below shows the remarkable fidelity that the coils are capable of reproducing, but the most amazing fact is that the musical modification actually produces diagnostically useful scans.

Our tastes don’t generally run to classical music, but having suffered through more than one head-banging scan, a half-hour of cello music would be a more than welcome change. Here’s hoping the technique gets further refined.

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Artificial Intelligence Composes New Christmas Songs

December 16, 2018 by Lewin Day 20 Comments

One of the most common uses of neural networks is the generation of new content, given certain constraints. A neural network is created, then trained on source content – ideally with as much reference material as possible. Then, the model is asked to generate original content in the same vein. This generally has mixed, but occasionally amusing, results. The team at [Made by AI] had a go at generating Christmas songs using this very technique.

The team decided that the easiest way to train their model would be to use note data from MIDI files. MIDI versions of Christmas songs are readily available and provide a broad base with which to train the model. For a neural network, the team chose to use a Long-short Term Memory (LSTM) architecture. This is a model which is contextually sensitive, which is important when dealing with structured formats like music or language.

The neural network generated five tunes which you can listen to on the Made by AI Soundcloud page. The team notes their time was limited, and we think that with some further work and more adherence to musical concepts such as structure and repetition, it might be possible to generate something a little more catchy.

There are other applications for AI in music, too – like these intelligent musical prostheses.

Mechanizing A Eurorack Sequencer

December 6, 2018 by Brian Benchoff 3 Comments

Eurorack has taken over the synthesizer community, and hundreds of people are building their own eurorack modules. [Michael Forrest] designed and built his own Eurorack sequencer module that doesn’t use weird things like capacitors and chips to store a signal. Instead, he’s doing it with stepper motors and some clever engineering.

The basic idea of a Eurorack sequencer is to somehow store a series of values and play them back repeatedly. Connect that sequence to a clock, and you get the same pattern of sounds out of your synth. This can be done digitally with a circular buffer, in the analog domain with a bunch of FETs and caps, or in this case, on a piece of paper glued to a stepper motor.

The key bit of mechanism for this build is a stepper motor with 96 steps per rotation. This is important, because the module is controlled by a clock pulse from the sequencer. Since 96 is evenly divisible by 8 and 16, that means this sequencer will play back in 4/4 time. That NEMA 17 motor with 200 steps per resolution simply won’t work in this situation. Rather, it will technically work, but it’ll be unusable.

The electronics for this build are surprisingly simple, with an Arduino taking in the clock pulse and sending the step signals to an H-driver. The motor spins a paper disk, which is read with a photoresistor and a LED. It’s simple enough to be fun, and yes, it is mounted to a proper Eurorack-sized panel. You can check out the video of this build below.

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Daphne Oram And The Birth Of Electronic Music

December 4, 2018 by Dan Maloney 10 Comments

For most of human history, musical instruments were strictly mechanical devices. The musician either plucked something, blew into or across something, or banged on something to produce the sounds the occasion called for. All musical instruments, the human voice included, worked by vibrating air more or less directly as a result of these mechanical manipulations.

But if one thing can be said of musicians at any point in history, it’s that they’ll use anything and everything to create just the right sound. The dawn of the electronic age presented opportunities galore for musicians by giving them new tools to create sounds that nobody had ever dreamed of before. No longer would musicians be constrained by the limitations of traditional instruments; sounds could now be synthesized, recorded, modified, filtered, and amplified to create something completely new.

Few composers took to the new opportunities offered by electronics like Daphne Oram. From earliest days, Daphne lived at the intersection of music and electronics, and her passion for pursuing “the sound” lead to one of the earliest and hackiest synthesizers, and a totally unique way of making music.

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An Englishman And 48 Gameboys Walk Into A Bar…

November 29, 2018 by Lewin Day 23 Comments

The original Nintendo Gameboy is perhaps one of the most revered platforms for the music known as chiptune. Primarily, artists will use the console with software like LSDJ or Nanoloop to produce their compositions. Some artists will even use two consoles when performing live. However, that’s all fairly quaint as far as [LOOK MUM NO COMPUTER] is concerned.

Back in 2016, a rig was constructed with three Gameboys. With each console having 3 oscillators and a noise channel, this gave plenty of scope. There was even a facility to detune the oscillators for a fatter sound.

Yet there remains a universal human philosophy – more is always better. In this vein, the plan is to create a monster machine consisting of 48 Gameboy consoles. This offers a somewhat maddening 144 oscillators and 48 noise channels to play with. The plan is to produce a massive synthesizer capable of producing incredibly thick, dense tones with up to six note polyphony.

The hardware side of things is at once simple and ingenious. Buttons on the consoles are connected together for remote control using ribbon cables and transistors. System clocks for the consoles are provided by a LTC1799 oscillator chip, which allows the clock to be modulated for audio effects. Initial tests with up to six Gameboys running from a single clock source have been remarkably successful.

Any mad scientist could see the genius involved in this project, and we can’t wait to see the full rig in operation. If you’re just getting started with Gameboy music, check out this primer on modding your Gameboy for hi-fi sound. Video after the break.

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