Pico-Driven Ultrasound Enables Scaled Acoustic Model Of Home Stereo

June 8, 2026 by Tyler August 2 Comments

There are plenty of ways to get sound into your house: good old fashioned headphones, the Dolby surround setup we all lusted after back in the day, or the 21st century’s ubiquitous soundbar, with its ‘spatial audio’ magic. Which will work in your space? If you were an audio engineer, you’d set up listening area and use a microphone to map the space– but that would be thousands of points and sounds like tedium. [PlasmatronX] had a better idea: use Schlieren imaging to see the sound waves as the travel through the space. Schlieren imaging has trouble with audio frequencies, though, and imaging the entire living room was going to be difficult. So he scaled it all down– including the sound waves, by shifting to ultrasonic frequencies.

He’s using the usual mirror-and-razor Schlieren setup with an 8″ telescope mirror– and if you don’t know what that is, we did a deep dive on this kind of optical flow visualizer a while back. Inside the circular imaging area where that lets him see density changes, he’s set up what he calls a CAT– Computer Acoustic Tomography– array. It’s a rig on a turntable he can set up ultrasonic transducers on, to match the various speaker setups he wants to test, and turn so he can see from all angles what the scaled-down waves are doing. To capture those waves, which aren’t going to be standing still, he adds a stroboscope. All the ultrasound signals are being generated by a Pi Pico, and are scaled 4:1 in the frequency domain– that is, a high 10kHz whine becomes inaudible 40kHz. Those signals are fed through a DIY 8-channel amp into both ultrasonic transducers and larger ‘cat-repellent speakers’ from AliExpress.

The microcontroller is actually a Pico 2W, which is using its “W” to communicate via Bluetooth with a Pi 4. That SBC is running the camera, the stepper for the turntable, and image processing, along with the timing for the audio signals. After that it’s a matter of setting up a scaled down 7.1 surround setup and itty-bity soundbar, and test it on a (stuffed) guinea pig. Obviously you can see a big difference between the steered beams from the tiny soundbar and the true surround, but how that translates to listening pleasure will be at least somewhat subjective.

What’s less subjective is the obvious effect soft furnishings add to the simulation. Now he doesn’t take the time to find a material that will scale the frequency response of a set of curtains, but we’re not sure how much that matters. At 5kHz or 20kHz, they’re going to deaden sound, and you can see that here, and you can see it’s a much bigger deal for the shaped beams of the soundbar than it is for surround sound. In the end, [PlasmatronX] decides to stick to headphones, but the whole video is very much worth watching, so we’ve embeddded it below. If you want to try it yourself he’s put his code on GitHub.

Thanks to [PlasmatronX] for the tip!

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Bluetooth Gramophone Has Surprisingly Contemporary Roots

June 7, 2026 by Tyler August 17 Comments

So you happen to have a gramaphone– maybe a big old Victrola/HMV, perhaps a Columbia– regardless of brand, it’s a big, beautiful conversation peice for your living room. It might not be the most practical listening device, since isnomuch as there is a vinyl renessance, it’s restricted to vinyl, not the old shellac 78s the these all-mechanical beasts were born for. [JGJMatt] decided to bring his gramophone into the 21st century, turning it into a bluetooth speaker without altering any of its original internals.

What’s really interesting is that this hack was once a commercial product– sort of. Back in the 1920s when everyone was listening to Jazz, the problem of ‘ what do I do with this massive gramophone cabinet when I’m not cutting a rug?’ was equally valid, and a solution was found: the Dulce-Tone Radio Speaker. A very weak speaker sits under the needle, turning the gramaphone mechanism into an amplifier for the radio. The very same concept, [JGJMatt] would work equally well in the 2020s with a bluetooth signal as in the 1920s with an AM one. There’s no demo video for this project, but you can hear how its 1920s inspiration sounded in the video below.

The driver for this device is made using a neodymium magnet and the voice coil from a 3W speaker. A 3D-printed needle-holder captures the gramophone’s needle– a much thicker and sturdier thing than the tiny diamond-tip you’d find on a modern turntable, we should note– and holds the magnet to it. The voice coil gets driven via a MH-M38 bluetooth module, and everything is held in a nice 3D-printed case along with the battery.

The hack is, of course, totally reversible: at any moment, you can remove the needle from this device and drop it on a 78 for some Jazz-era fun, or swap back for 21st century brainrot. If you happen to have some of those old shellac records and a modern turntable, note it takes more than the right RPM to get good sound. Continue reading “Bluetooth Gramophone Has Surprisingly Contemporary Roots” →

The turntable in question, or at least the same model.

Vintage Turntable Gets Brain Transplant And Home Assistant Integration

June 5, 2026 by Tyler August 10 Comments

When [Marsupial] picked up a vintage Sansusi P-L45 turntable, he figured it would be an easy fix: a few capacitors, a belt or two, and maybe a new cartridge, the usual. But it turned out the electronics were fried, which set the stage for an upgrade that turned it into what may be the world’s only ESP32-driven, Home Assistant integrated, linear tracking turntable.

That last bit, the linear tracking, is why the turntable originally had a microprocessor in the first place: rather than an arm that pivots along the groove naturally, fancy turntables towards the end of the golden era of vinyl slid the needle along a linear track at a variable speed to follow the spiral groove on the record. You can see that in action in the demo video below, though it’s of a working version owned by [BFinks].

The fancy linear mechanism required electronic control to match the speed to the RPM, and in the example of Sansusi’s P-L45, that was provided by an NEC microcontroller on a daughter-board labelled “F4992 CPU”. CPU is a grandiose title, perhaps, but that’s irrelevant since the chip on the board was deader than disco.

That meant [Marsupial] had some reverse engineering to do — figuring out exactly what that chip did to drive this board, in order to replicate its behavior on an ESP32-S3. Luckily the golden era of vinyl correlated with the golden era of service manuals, and the manuals are still available, so [Marsupial] had a big leg up on that. After making the turntable work like stock, what else to do with the extra capability of the ESP32 than plug it into HA and make it really automatic?

Of course it wasn’t quite that easy: a new daughter-board was created that needed to do level shifting to the ESP32’s modern 3.3 V logic as well as hardware debounce on some inputs. The whole saga is very well documented on [Marsupial]’s blog WeAreAllGeeks. The link here takes you to the overview, but he’s got a lot more info on other pages — and of course links to the firmware and PCB design if you happen to have a Sansusi turntable in need of a brain transplant.

Vinyl lovers will appreciate this project much more than the last ESP32 “turntable” we featured, which was anything but. If you want to get into records but don’t have a turntable, you can always make your own.

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The Maths Behind A Chord Recognition Engine

May 22, 2026 by Zoe Skyforest 13 Comments

A key part of any tertiary musical education is learning about all the wonderful (and less wonderful) types of chords out there. Typically this involves a great deal of exercises involving the identification of a given chord from its component notes. But how would you do this programmatically? Well, thankfully, the developers behind the WhatChord tool are happy to explain just how it’s done.

The problem with classifying chords is that the way musicians use them and construct them can be quite varied. Names can also be applied somewhat differently depending on the musical context of a given set of notes. To suit the musical reality of real players and composers, WhatChord uses a specially-developed scoring algorithm to try and nut out what a chord is actually supposed to be.

As an example, a major chord must require a root note and a major third interval. It can optionally include a perfect fifth. However, if there is a minor third, minor seventh, or major seventh present, then you’re almost certainly not looking at a simple major chord. WhatChord takes these things into account by weighting the different tones present and seeing which chord gets the highest score. The required notes add weight, while notes that shouldn’t be there add a penalty to the score. Then there are extra penalties for ambiguous “unexplained” tones, extensions, and a few other parameters to disambiguate edge cases.

If you’d like to see how it works in practice, you can check out the WhatChord app and see how good it is for yourself. Alternatively, explore some of the other chord-focused projects we’ve featured over the years, or send your best musical projects into the tipsline.

[Thanks to baschwar for the tip!]

NFC Record Player Promotes Intentional Listening

May 17, 2026 by Bryan Cockfield 16 Comments

Streaming services have enabled many of us to have easy access to the world’s media library at the touch of a screen, but [Coconauts] thinks we’ve lost something along the way. To bring some intentionality back to the listening experience, they built an NFC record player called Minilos.

Like a normal record player, Minilos requires the user to select an album to play on the machine. These were originally decorative coasters with records printed on them, so they are much smaller than even a 45. Each one features an NFC tag that instructs ESP32 microcontroller hidden in the device to play the requested song. Once placed on the record player, it will then play through that album and come to a stop.

In [Coconauts]’s current setup, the ESP32 is connected to a Home Assistant server which then instructs a Google Speaker to play the requested song via Spotify, although we could easily imagine this being used to play music directly from an SD card or other digital storage device instead.

If you want complete control over your music listening while still keeping that authentic vinyl experience, you could always look into cutting your own records with a laser.

Mixapps: The Mixtape Of The Internet Age

May 16, 2026 by Zoe Skyforest 53 Comments

Mixtapes used to be a way that we cultivated a personal selection of music for our own enjoyment, or to give as gifts to those we wanted to impress with a personal touch. These days, we’d typically try that with a playlist, but it’s less romantic despite also being more ephemeral. Songs fall off streaming services all the time, and few of us have the exact same subscriptions as those we’re trying to flirt with. Thus, [Hunter Irving] whipped up a more lasting solution for this modern age.

The concept is simple—it’s a collection of songs that are packaged together in a easily portable format that won’t disappear because of corporate bureaucratic nonsense. [Hunter] has termed their project Mixapps—because it’s a method of sharing music based around Progressive Web Apps (PWA). To create a custom mix, you start by running a Python script, which will then let you add tracks and reorder them as you desire. From there, you run a second script that builds the web app for you.

You can then upload the prepared app directory to a web host to share it with anyone you like. They can then save the PWA to the home screen of their mobile device, where it will live happily ever after. There’s no need to keep hosting the app online or for the user to remain connected to the Internet; everything is self contained on their device. If you’re curious, there’s a demo you can check out online.

It’s worth noting that there are intellectual property concerns to be had as with any form of music sharing, but what else is new? We’ve explored the magic of mixtapes in the past, anyway, to be sure. If you’re finding new ways to trade music and playlists, romantically or platonically, don’t hesitate to let us know.

Win95-Tracker-CYD Is A Cheap Yellow Mod Tracker With I2S

May 8, 2026 by Tyler August 7 Comments

The Cheap Yellow Display is a great little module to start a project with, but it wouldn’t necessarily be our first choice for an audio device. That’s because the PWM on the ESP32 isn’t exactly going to put out hi-fi, and the I2C pins needed for the I2S audio protocol aren’t broken out on the CYD board. That didn’t stop [ivans805] AKA [Ill-Town-5623]– he wanted a mod tracker, he had a CYD board, and necessity is the mother of invention.

It isn’t exactly a ground-breaking hack: he’s just tossed a bodge wire to the pin he needs on the ESP32, and run it to the I2S sound module. Still, in this era of endless modules it’s nice to see someone hacking what they have rather than running to AliExpress or somewhere else for a part that has everything the project needs built in.

The bodge wire is how you know it’s a hack.

What really caught our eye when we saw this project on the ESP32 subreddit was the aesthetics. It might be called “Win95-Tracker-CYD” but that interface just screams “Amiga” to us– look at that Boing Ball! Given where MOD files come from, that’s perfect. The UI was made with Lopaka.app, which we haven’t seen before but appears to be a sort of WYSIWYG editor for embedded device interfaces.

While you don’t need an ESP32 to play mod files– the diminutive CH32 can manage the task— there’s no arguing the CYD could make a nice little player. If you actually wanted to push its limits, you might try a 3D engine instead,