Musical Hacks

1399 Articles

Taking Cues From A Gramophone To Make A Better Marble Music Machine

February 25, 2025 by 12 Comments

[Martin] of [Wintergatan] is on a quest to create the ultimate human-powered, modern marble music machine. His fearless mechanical exploration and engineering work, combined with considerable musical talent, has been an ongoing delight as he continually refines his designs. We’d like to highlight this older video in which he demonstrates how to dynamically regulate the speed of a human-cranked music machine by taking inspiration from gramophones: he uses a flyball governor (or centrifugal governor).

The faster the shaft turns, the harder the disk brake is applied.

These devices are a type of mechanical feedback system that was invented back in the 17th century but really took off once applied to steam engines. Here’s how they work: weights are connected to a shaft with a hinged assembly. The faster the shaft spins, the more the weights move outward due to centrifugal force. This movement is used to trigger some regulatory action, creating a feedback loop. In a steam engine, the regulator adjusts a valve which keeps the engine within a certain speed range. In a gramophone it works a wee bit differently, and this is the system [Wintergatan] uses.

To help keep the speed of his music machine within a certain narrow range, instead of turning a valve the flyball governor moves a large disk brake. The faster the shaft spins, the harder the brake is applied. Watch it in action in the video (embedded below) which shows [Wintergatan]’s prototype, demonstrating how effective it is.

[Wintergatan]’s marble machine started out great and has only gotten better over the years, with [Martin] tirelessly documenting his improvements on everything. After all, when every note is the product of multiple physical processes that must synchronize flawlessly, it makes sense to spend time doing things like designing the best method of dropping balls.

One final note: if you are the type of person to find yourself interested and engaged by these sorts of systems and their relation to obtaining better results and tighter tolerances, we have a great book recommendation for you.

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Parametric Design Process Produces Unique Speakers

February 17, 2025 by 28 Comments

When building one-off projects, it’s common to draw up a plan on a sheet of paper or in CAD, or even wing it and hope for the best outcome without any formal plans. Each of these design philosophies has its ups and downs but both tend to be rigid, offering little flexibility as the project progresses. To solve this, designers often turn to parametric design where changes to any part of the design are automatically reflected throughout the rest, offering far greater flexibility while still maintaining an overall plan. [Cal Bryant] used this parametric method to devise a new set of speakers for an office, with excellent results.

The bulk of the speakers were designed with OpenSCAD, with the parametric design allowing for easy adjustments to accommodate different drivers and enclosure volumes. A number of the panels of the speakers are curved as well, which is more difficult with traditional speaker materials like MDF but much easier with this 3D printed design. There were a few hiccups along the way though; while the plastic used here is much denser than MDF, the amount of infill needed to be experimented with to achieve a good finish. The parametric design paid off here as well as the original didn’t fit exactly within the print bed, so without having to split up the print the speakers’ shape was slightly tweaked instead. In the end he has a finished set of speakers that look and sound like a high-end product.

There are a few other perks to a parametric design like this as well. [Cal] can take his design for smaller desk-based speakers and tweak a few dimensions and get a model designed to stand up on the floor instead. It’s a design process that adds a lot of options and although it takes a bit more up-front effort it can be worth it while prototyping or even for producing different products quickly. If you want to make something much larger than the print bed and slightly changing the design won’t cut it, [Cal] recently showed us how to easily print huge objects like arcade cabinets with fairly standard sized 3D printers.

Piano Gets An Arduino Implant

February 16, 2025 by 18 Comments

[Paul] likes his piano, but he doesn’t know how to play it. The obvious answer: program an Arduino to do it. Some aluminum extrusion and solenoids later, and it was working. Well, perhaps not quite that easy — making music on a piano is more than just pushing the keys. You have to push multiple keys together and control the power behind each strike to make the music sound natural.

The project is massive since he chose to put solenoids over each key. Honestly, we might have been tempted to model ten fingers and move the solenoids around in two groups of five. True, the way it is, it can play things that would not be humanly possible, but ten solenoids, ten drivers, and two motors might have been a little easier and cheaper.

The results, however, speak for themselves. He did have one problem with the first play, though. The solenoids have a noticeable click when they actuate. The answer turned out to be orthodontic rubber bands installed on the solenoids. We aren’t sure we would have thought of that.

Player pianos, of course, are nothing new. And, yes, you can even make one with a 555. If a piano isn’t your thing, maybe try a xylophone instead.

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Hearing What The Bats Hear

February 11, 2025 by 9 Comments

[Iftah] has been exploring the sounds beyond what we can hear, recording ultrasound and pitching it down. He made a short video on the practice, and it’s like a whole new world of sounds exists just outside of our hearing.

For instance, a dropped toothpick sounds like you’ve just dropped a piece of lumber, a broken lightbulb sounds like a shattered window, and a blackbird sounds like a blue whale. Besides simply sounding super, [Iftah] speculates that there’s some regularity here: that as you slow down the sound it sounds like it came from sources that are physically bigger. He follows this up in a second video, but if you just think about the basic physics, it makes sense.

If you’re interested in recording your own ultrasound, there are a bunch of options on the market. With modern audio processors running up to 192 kHz or even 384 kHz out of the box, all that’s missing is the high-frequency-capable microphone. Those aren’t unobtainable anymore either with many MEMS mics performing well above their rated frequency response specs. Recording ultrasound sounds like a fun and not-too-expensive project to us!

Of course, most of the ultrasound recording we’ve seen has been about the bats. Check out the Pipistrelle or this pair of DIY bat detectors for some good background. But after watching [Iftah]’s video, we’re no longer convinced that the cute little insectivores are the coolest thing going on in the ultrasound.

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Cyberbass Brings Bass Guitar To Modern Era

February 4, 2025 by 19 Comments

For better or worse, the fundamental design of guitars has remained familiar since they electrified around a century ago. A few strings, a fretboard, and a body of some sort will get you most of the way there for an acoustic guitar, with the addition of electromagnetic pickups and wiring for electric variants. However, technology has advanced rapidly in the last 100 years outside the musical world, so if you want to see what possibilities lie ahead for modernizing guitars take a look at the Cyberbass created by [Matteo].

The guitar starts its life as many guitars do: with a block of wood. One of the design goals was to be able to use simple tools to build the guitar, so the shape of the instrument was honed with a Japanese hacksaw and the locations for the pickups and other electronics were carved out with chisels.

The neck of the guitar was outsourced since they take some pretty specialized tools to build, so simply bolting it to the body takes care of that part of the build, but [Matteo] had a few false starts setting the bridge in the exact location it needed to be.

Luckily he was able to repair the body and move the bridge. With the core of the guitar ready, it was on to paint and then to its custom electronics. [Matteo] built in not only a set of pickups and other common electric guitar parts but also integrated a synth pedal into the body as well as including a chromatic tuner.

With everything assembled and a few finishing touches added including a custom-engraved metal signature plate, the Cyberbass is ready to go on tour. [Matteo] learned a lot about guitar building in general, as well as a few things about electronics relating to musical instruments (including how expensive tuners work just as well as cheap ones).

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Homebrew Foil And Oil Caps Change Your Guitar’s Tone

February 4, 2025 by 47 Comments

How any string instrument sounds depends on hundreds of factors; even the tiniest details matter. Seemingly inconsequential things like whether the tree that the wood came from grew on the north slope or south slope of a particular valley make a difference, at least to the trained ear. Add electronics into the mix, as with electric guitars, and that’s a whole other level of choices that directly influence the sound.

To experiment with that, [Mark Gutierrez] tried rolling some home-brew capacitors for his electric guitar. The cap in question is part of the guitar’s tone circuit, which along with a potentiometer forms a variable low-pass filter. A rich folklore has developed over the years around these circuits and the best way to implement them, and there are any number of commercially available capacitors with the appropriate mojo you can use, for a price.

[Mark]’s take on the tone cap is made with two narrow strips of regular aluminum foil separated by two wider strips of tissue paper, the kind that finds its way into shirt boxes at Christmas. Each of the foil strips gets wrapped around and crimped to a wire lead before the paper is sandwiched between. The whole thing is rolled up into a loose cylinder and soaked in mineral oil, which serves as a dielectric.

To hold the oily jelly roll together, [Mark] tried both and outer skin of heat-shrink tubing with the ends sealed by hot glue, and a 3D printed cylinder. He also experimented with a wax coating to keep the oily bits contained. The video below shows the build process as well as tests of the homebrew cap against a $28 commercial equivalent. There’s a clear difference in tone compared to switching the cap out of the circuit, as well as an audible difference in tone between the two caps. We’ll leave the discussion of which sounds better to those with more qualified ears; fools rush in, after all.

Whatever you think of the sound, it’s pretty cool that you can make working capacitors so easily. Just remember to mark the outer foil lead, lest you spoil everything.

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Shellcode Over MIDI? Bad Apple On A PSR-E433, Kinda

January 23, 2025 by 6 Comments

If hacking on consumer hardware is about figuring out what it can do, and pushing it in directions that the manufacturer never dared to dream, then this is a very fine hack indeed. [Portasynthica3] takes on the Yamaha PSR-E433, a cheap beginner keyboard, discovers a shell baked into it, and takes it from there.

[Portasynthinca3] reverse engineered the firmware, wrote shellcode for the device, embedded the escape in a MIDI note stream, and even ended up writing some simple LCD driver software totally decent refresh rate on the dot-matrix display, all to support the lofty goal of displaying arbitrary graphics on the keyboard’s dot-matrix character display.

Now, we want you to be prepared for a low-res video extravaganza here. You might have to squint a bit to make out what’s going on in the video, but keep in mind that it’s being sent over a music data protocol from the 1980s, running at 31.25 kbps, displayed in the custom character RAM of an LCD.

As always, the hack starts with research. Identifying the microcontroller CPU lead to JTAG and OpenOCD. (We love the technique of looking at the draw on a bench power meter to determine if the chip is responding to pause commands.) Dumping the code and tossing it into Ghidra lead to the unexpected discovery that Yamaha had put a live shell in the device that communicates over MIDI, presumably for testing and development purposes. This shell had PEEK and POKE, which meant that OpenOCD could go sit back on the shelf. Poking “Hello World” into some free RAM space over MIDI sysex was the first proof-of-concept.

The final hack to get video up and running was to dig deep into the custom character-generation RAM, write some code to disable the normal character display, and then fool the CPU into calling this code instead of the shell, in order to increase the update rate. All of this for a thin slice of Bad Apple over MIDI, but more importantly, for the glory. And this hack is glorious! Go check it out in full.

MIDI is entirely hacker friendly, and it’s likely you can hack together a musical controller that would wow your audience just with stuff in your junk box. If you’re at all into music, and you’ve never built your own MIDI devices, you have your weekend project.

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