Musical Hacks

1472 Articles

Pi Pico Throws Us For A (MIDI) Loop

April 28, 2025 by 3 Comments

Modern micro-controllers are absolute marvels, but it isn’t too many projects use one and nothing else. For an example of such simplicity, take a look at [oyama]’s Pi Pico MIDI looper.

It uses the PicoW to interface with a synth via MIDI-BLE, which can be anything from pro equipment to an app on your smartphone. The single control button is already provided by the Pico W– the bootsel button is wearing a lot of hats here, allowing one to select betwixt 4 tracks (all different drums), set the tempo, and input notes on the selected track.

The action is simple: pound out the rhythm for each track, and it will repeat forever, or at least until you press the single button again to change it. There’s also a nice serial interface so you can see what’s going on via UART or USB. For what it does, it is amazingly simple: the BOM is one item, the Pi Pico W. To see it in action, check out the demo video below.

Given the ADC chops on the Pico, it would probably be easy to extend this build with a speaker to make a tiny stand-alone, one-button synth. Or you could add more buttons buttons, but then it’s no longer the beautifully simple single-line BOM project that [oyama] showed us.

Of course, everything is open-source on GitHub, under the BSD license, and forking is encouraged, so [oyama] would doubtless be more than happy to see you go nuts hacking and extending this tiny MIDI looper.

We’ve actually seen the MIDI-BLE standard used before, like this hack adding it to a Eurorack. If you like synths, you may be interested to see what it takes to design one from scratch, sans microcontroller. Continue reading “Pi Pico Throws Us For A (MIDI) Loop” →

Look! It’s A Knob! It’s A Jack! It’s Euroknob!

April 28, 2025 by 25 Comments

Are your Eurorack modules too crowded? Sick of your patch cables making it hard to twiddle your knobs? Then you might be very interested in the new Euroknob, the knob that sports a hidden patch cable jack.

Honestly, when we first saw the Euroknob demo board, we thought [Mitxela] had gone a little off the rails. It looks like nothing more than a PCB-mount potentiometer or perhaps an encoder with a knob attached. Twist the knob and a row of LEDs on the board light up in sequence. Nice, but not exactly what we’re used to seeing from him. But then he popped the knob off the board, revealing that what we thought was the pot body is actually a 3.5-mm audio jack, and that the knob was attached to a mating plug that acts as an axle.

The kicker is that underneath the audio jack is an AS5600 magnetic encoder, and hidden in a slot milled in the tip of the audio jack is a tiny magnet. Pop the knob into the jack, give it a twist, and you’ve got manual control of your module. Take the knob out, plug in a patch cable, and you can let a control voltage from another module do the job. Genius!

To make it all work mechanically, [Mitxela] had to sandwich a spacer board on top of the main PCB. The spacer has a large cutout to make room for the sensor chip so the magnet can rotate without hitting anything. He also added a CH32V003 to run the encoder and drive the LEDs to provide feedback for the knob-jack. The video below has a brief demo.

This is just a proof of concept, to be sure, but it’s still pretty slick. Almost as slick as [Mitxela]’s recent fluid-motion simulation pendant, or his dual-wielding soldering irons.

Continue reading “Look! It’s A Knob! It’s A Jack! It’s Euroknob!” →

Amazing Oscilloscope Demo Scores The Win At Revision 2025

April 26, 2025 by 34 Comments

Classic demos from the demoscene are all about showing off one’s technical prowess, with a common side order of a slick banging soundtrack. That’s precisely what [BUS ERROR Collective] members [DJ_Level_3] and [Marv1994] delivered with their prize-winning Primer demo this week.

This demo is a grand example of so-called “oscilloscope music”—where two channels of audio are used to control an oscilloscope in X-Y mode. The sounds played determine the graphics on the screen, as we’ve explored previously.

The real magic is when you create very cool sounds that also draw very cool graphics on the oscilloscope. The Primer demo achieves this goal perfectly. Indeed, it’s intended as a “primer” on the very artform itself, starting out with some simple waveforms and quickly spiraling into a graphical wonderland of spinning shapes and morphing patterns, all to a sweet electronic soundtrack. It was created with a range of tools, including Osci-Render and apparently Ableton 11, and the recording performed on a gorgeous BK Precision Model 2120 oscilloscope in a nice shade of green.

If you think this demo is fully sick, you’re not alone. It took out first place in the Wild category at the Revision 2025 demo party, as well as the Crowd Favorite award. High praise indeed.

We love a good bit of demoscene magic around these parts.

Continue reading “Amazing Oscilloscope Demo Scores The Win At Revision 2025” →

Revivification: a Room with cymbals and plinth

Posthumous Composition Being Performed By The Composer

April 25, 2025 by 15 Comments

Alvin Lucier was an American experimental composer whose compositions were arguably as much science experiments as they were music. The piece he is best known for, I Am Sitting in a Room, explored the acoustics of a room and what happens when you amplify the characteristics that are imparted on sound in that space by repeatedly recording and playing back the sound from one tape machine to another. Other works have employed galvanic skin response sensors, electromagnetically activated piano strings and other components that are not conventionally used in music composition.

Undoubtedly the most unconventional thing he’s done (so far) is to perform in an exhibit at The Art Gallery of Western Australia in Perth which opened earlier this month. That in itself would not be so unconventional if it weren’t for the fact that he passed away in 2021. Let us explain.

Continue reading “Posthumous Composition Being Performed By The Composer” →

Open Source Commercial Synthesisers You Will Love

April 23, 2025 by 17 Comments

Drumboy and Synthgirl from Randomwaves are a a pair of compact electronic instruments, a drum machine and a synthesiser. They are commercial products which were launched on Kickstarter, and if you’re in the market for such a thing you can buy one for yourself. What’s made them of interest to us here at Hackaday though is not their musical capabilities though, instead it’s that they’ve honoured their commitment to release them as open source in the entirety.

So for your download, you get everything you need to build a pair of rather good 24-bit synthesisers based upon the STM32 family of microcontrollers. We’re guessing that few of you will build your own when it’s an easier job to just buy one from Randomwaves, and we’re guessing that this open-sourcing will lead to interesting new features and extensions from the community of owners.

It will be interesting to watch how this progresses, because of course with the files out there, now anyone can produce and market a clone. Will AliExpress now be full of knock-off Drumboys and Synthgirls? It’s a problem we’ve looked at in the past with respect to closed-source projects, and doubtless there will be enterprising electronics shops eyeing this one up. By our observation though it seems to be those projects with cheaper bills of materials which suffer the most from clones, so perhaps that higher-end choice of parts will work in their favour.

Either way we look forward to more open-source from Randomwaves in the future, and if you’d like to buy either instrument you can go to their website.

Thanks [Eilís] for the tip.

This is the Rockbox logo banner.

Rockbox 4.0 Released

April 19, 2025 by 25 Comments

It’s traditional to launch new software on April Fool’s Day, which is when we heard that Rockbox 4.0 has been released. But, in this case, the venerable MP3 firmware actually did update after a long absence. It’s great to see that good old Rockbox is still kicking along. We first mentioned Rockbox here at Hackaday approaching 20 years ago. How time flies. There used to be a whole ‘scene’ around hacking Personal Media Players (PMPs), also known as “MP3 Players”.

We tracked down Rockbox contributor [Solomon Peachy] to ask for some simple advice: If someone wants to install Rockbox on a personal media player today, what hardware should they buy? [Solomon] referred us to the AIGO EROS Q / EROS K, which is the only compatible hardware still being manufactured and sold. Beyond that, if you want to buy compatible hardware, you’ll need to find some secondhand somewhere, such as eBay. See the Rockbox Wiki for supported hardware.

Smartphones and streaming services have subsumed the single-purpose personal media player. Will you put the new Rockbox on something? Let us know in the comments.

Designing An FM Drum Synth From Scratch

April 17, 2025 by 14 Comments

How it started: a simple repair job on a Roland drum machine. How it ended: a scratch-built FM drum synth module that’s completely analog, and completely cool.

[Moritz Klein]’s journey down the analog drum machine rabbit hole started with a Roland TR-909, a hybrid drum machine from the mid-80s that combined sampled sounds with analog synthesis. The unit [Moritz] picked up was having trouble with the decay on the kick drum, so he spread out the gloriously detailed schematic and got to work. He breadboarded a few sections of the kick drum circuit to aid troubleshooting, but one thing led to another and he was soon in new territory.

The video below is on the longish side, with the first third or so dedicated to recreating the circuits used to create the 909’s iconic sound, slightly modifying some of them to simplify construction. Like the schematic that started the whole thing, this section of the video is jam-packed with goodness, too much to detail here. But a few of the gems that caught our eye were the voltage-controlled amplifier (VCA) circuit that seems to make appearances in multiple places in the circuit, and the dead-simple wave-shaper circuit, which takes some of the harmonics out of the triangle wave oscillator’s output with just a couple of diodes and some resistors.

Once the 909’s kick and toms section had been breadboarded, [Moritz] turned his attention to adding something Roland hadn’t included: frequency modulation. He did this by adding a second, lower-frequency voltage-controlled oscillator (VCO) and using that to modulate the drum section. That resulted in a weird, metallic sound that can be tuned to imitate anything from a steel drum to a bell. He also added a hi-hat and cymbal section by mixing the square wave outputs on the VCOs through a funky XOR gate made from discrete components and a high-pass filter.

There’s a lot of information packed into this video, and by breaking everything down into small, simple blocks, [Moritz] makes it easy to understand analog synths and the circuits behind them.

Continue reading “Designing An FM Drum Synth From Scratch” →