Web Assembly, Music Synthesis, And The Beauty Of Math

The electronics hobby has changed a lot since the advent of the microprocessor. Before that — and with the lack of large-scale integrated circuits — projects in magazines tended to be either super simple or ultra complex. However, one popular type of project dealt with music synthesis. Fairly simple circuits could combine to make a complex synthesizer so it was sort of the best of both worlds. Nowadays, you are more likely to tackle a music synthesizer in software like [Tim] did when he created Abelton in Web Assembly and C++. Along the way, he learned a lot about the relationship between math and music.

[Tim] covers what he learned about the Nyquist theorem and how to keep synthesis data flowing in real time with buffers. However, there are some problems trying to do all this in a cross-browser context. The AudioWorklet class appears to have widespread support, though, and [Tim] managed to get that working.

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MIDI All The Things Hack Chat

Join us on Wednesday, March 24 at noon Pacific for the MIDI All the Things Hack Chat with Tim Alex Jacobs!

In our technologically complex world, standards are a double-edged sword. While they clearly make it possible for widgets and doodads to interoperate with each other, they also tend to drift away from their original intention over time, thanks to the march of progress or even market forces. If there’s one thing you can expect about standards, it’s that they beget other standards.

One standard that has stood the test of time, with modification of course, is the Musical Instrument Digital Interface, or MIDI. It’s hard to overstate the impact MIDI has had on the music world since it was first dreamed up in the early 1980s. Started amid a Wild West of competing proprietary synchronization standards, MIDI quickly became the de facto interface for connecting electronic musical instruments together. And as it did, it moved from strictly pro-grade equipment down the market to prosumer and home users, fueled in part by the PC revolution.

Tim Alex Jacobs, who is perhaps better known as Mitxela on his YouTube channel, has long been interested in applying MIDI to unusual corners of the musical world. We’ve seen him MIDI-fy things that barely qualify as musical instruments, and also build a polyphonic synthesizer so small it fits within the shell of the DIN connector that’s so strongly associated with the MIDI standard. Tim joins us on the Hack Chat this week to talk about his experiences with MIDI, and to help us understand all the ways we can work with the interface in our builds.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, March 24 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
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Homebrew Grain Synth Has A Rad Step Sequencer

In the world of homebrew synthesizers, there are plenty of noiseboxes and grooveboxes that make all kinds of wacky and wild noises. However, common projects like the Auduino and Atari Punk Console are often limited in that they can’t readily be programmed to play multiple notes or any sort of discernable rhythm. [Nick Poole] changes this with his Auduino step sequencer build.

The build takes the Auduino grain synthesizer, and modifies it by adding a step sequencer. This is possible as the Auduino code, which runs on the old-school ATMEGA-based Arduinos, is incredibly fast, leaving plenty of processing time for extra features to be added. [Nick] adds eight LEDs and eight buttons to the build, allowing the user to select one of eight steps to modify. Then, the sound parameters for the step can be altered with the standard Auduino controls. This lets the user quickly and easily build up 8-step melodies, something that was previously impossible with the Auduino.

It’s a fun build, and one that makes a great intro into the world of DIY synth builds. The techniques learned here will serve any aspiring maker well if they dive further into the world of modular synthesis and associated arcana. Video after the break.

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Peek Into This Synth’s Great Design (And Abandoned Features)

[Tommy]’s POLY555 is an analog, 20-note polyphonic synthesizer that makes heavy use of 3D printing and shows off some clever design. The POLY555, as well as [Tommy]’s earlier synth designs, are based around the 555 timer. But one 555 is one oscillator, which means only one note can be played at a time. To make the POLY555 polyphonic, [Tommy] took things to their logical extreme and simply added multiple 555s, expanding the capabilities while keeping the classic 555 synth heritage.

The real gem here is [Tommy]’s writeup. In it, he explains the various design choices and improvements that went into the POLY555, not just as an instrument, but as a kit intended to be produced and easy to assemble. Good DFM (Design For Manufacturability) takes time and effort, but pays off big time even for things made in relatively small quantities. Anything that reduces complexity, eliminates steps, or improves reliability is a change worth investigating.

For example, the volume wheel is not a thumbwheel pot. It is actually a 3D-printed piece attached to the same potentiometer that the 555s use for tuning; meaning one less part to keep track of in the bill of materials. It’s all a gold mine of tips for anyone looking at making more than just a handful of something, and a peek into the hard work that goes into designing something to be produced. [Tommy] even has a short section dedicated to abandoned or rejected ideas that didn’t make the cut, which is educational in itself. Want more? Good news! This isn’t the first time we’ve been delighted with [Tommy]’s prototyping and design discussions.

POLY555’s design files (OpenSCAD for enclosure and parts, and KiCad for schematic and PCB) as well as assembly guide are all available on GitHub, and STL files can be found on Thingiverse. [Tommy] sells partial and complete kits as well, so there’s something for everyone’s comfort level. Watch the POLY555 in action in the video, embedded below.

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Free To Good Home: FPGA Supercharged Audio/Video Synthesizer

Audio and video synthesizers have been around for decades, and are pretty much only limited by one’s willingness to spend money on them.  That is, unless you can develop your own FPGA-supercharged synthesizer to really get a leg up on the consumer-grade components. Of course, as [Julian] found out in this four-year project, you tend to pay for it anyway in time spent working on your projects.

[Julian] has actually decided to stop working on the project and open-source it to anyone who wants to continue on. He has already finished the PCB layout on a gargantuan 8-layer print, done all of the routing and parts selection, and really only needed to finish testing it to complete the project. It’s powered by the Xilinx Zynq and is packed with features too: HDMI, DDR3 ram, USB, a handful of sensors, and an Arduino Uno-style header to make interfacing and programming a breeze.

While we’re sympathetic with setting aside a project that we’ve worked so hard on, with most of the work done on this one it should be pretty easy to pick up and adapt for anyone interested in carrying the torch. If you were hoping to wet your whistle with something with fewer PCB layers, though, we’ve seen some interesting (but slightly simpler) video synthesizers made out of other unique hardware as well.

 

Sounding The Humble LED

Here at Hackaday we’re no strangers to the colorful glow of LEDs. But what if there was more to appreciate beneath the surface? Back in 2011 [Windell] over at Evil Mad Scientist dug into a certain variety of LED and discovered they had a song to sing.

Over the last couple decades, you’ve likely encountered the flickering “candle flame” variety of LED. Often found embedded in small plastic candle simulacra they are shaped like typical through hole “gumdrop” style LEDs, but pack some extra magic which causes them to flicker erratically. Coupled with a warm white color temperature the effect isn’t entirely dissimilar to the flickering of a candle flame.

To the Hackaday reader (and [Windell]) the cause of the flickering may be fairly clear, there is an IC embedded in the lens of the LED. See photo at top for an example of how this might look, helpfully magnified by the lens of the LED itself. Looking through the lens the captive die is visible, as well as the bond wires connecting it to the legs and light emitting diode itself. [Windell]’s observation is that together this assembly makes for a somewhat strange electrical component; from the perspective of the circuit it appears to randomly vary the current flowing through the LED.

He includes two interesting demos. One is that by attaching the flickering LED to a BJT he can turn it into a current amplifier and successfully drive a much more powerful 1W LED with the same effect. The other is that  with the power of the amplifier the same flickering LED can drive a buzzer as well. The effect is surprisingly pleasant, though we’d hesitate to call it musical.

For a more recent example of a similar phenomenon with a very different sound, check out out [Emily Velasco]’s playback of a similarly constructed RGB color changing LED, embedded below. We’ve seen optical tools used to decode LED flickers into data streams, but not for audio playback! We have also covered some LED flicker reverse engineering that spills more of the mystery sealed up in these specialized diodes.

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We Bet You’ve Never Seen A Pink Denture Synth

At one end of the synthesizer world, there stands commercial instruments designed for the ultimate in sound quality and performance, tailored to the needs of professional musicians. On the other, there are weird, wacky prototypes and artistic builds that aim to challenge our conception of what a synth should be. The VOC-25 by [Love Hultén] falls firmly in the latter category.

The synth is built around the Axoloti Core, a microcontroller board set up for audio experimentation. Packing stereo DACs and ADCs, and MIDI input and output, it’s the perfect base for such a project. Loaded up with vocal samples, it’s played by a keyboard in a fairly typical sense. Where things get interesting is the panel containing 25 sets of plastic teeth. The teeth open and close when the user plays the corresponding note, thanks to a solenoid. Along with the clacking sound of the machinery and pearly whites themselves, it adds quite a creepy vibe to the piece.

With its clean pastel enclosure, we can imagine this piece as the star of an avant-garde filmclip, or merely something to terrify children at a Maker Faire. It’s a fun build, to be sure. We’ve seen some other great experimental synths over the years, too – this 48 Game Boy build comes to mind. Video after the break.

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