Sonos Speakers Free To Sing Again

Over at the EEVBlog, [Dave Jones] takes a second look at the Sonos Play 5 Gen 1 that he rescued from the dumpster recently. Despite being solidly built, [Dave] discovered that even the stereo line-in jack can’t be used without registering an account with Sonos. Not to be defeated, he hacks these speakers to make them work standalone.

Bluetooth Audio Amplifier Module (Fosi Audio)

The hack here involves fitting the speaker cabinet with new “guts” in the form of a wireless stereo 2×50 watt digital amplifier [Dave] found online for under $30. This particular model, the Fosi TB21, is almost a perfect fit for the Sonos cabinet — with only minimal Dremel tool encouragement required. It turned out the power supply section of the Sonos main board was easy to isolate. [Dave] couldn’t use the existing amplifiers, so he removed them from their power supply and re-routed the power supply to the Fosi module. He also removed the Sonos wireless interface board from the cabinet, and used an online design tool to make a simple first order Butterworth crossover network set to 2800 Hz to connect the speakers.

The new amplifier board is mounted in the shallow base of the speaker cabinet. It could have easily been oriented either way, but [Dave] chose to install it knobs-forward. This also gave him a reason to toss out the Sonos badge. The resulting modified unit looks very professional, and works well as a Bluetooth speaker for the lab.

We wrote about the opposite conversion last year, where old speakers from the 1960s were hacked to add Sonos capability. You can read about the controversy surrounding Sonos here, and we discussed the issue on the Hackaday Podcast in episode 058.

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Camera-Mounted Stereo Mic Is Fluffy And Capable

Typically, the audio coming out of your camera is not of the greatest quality. An external mic is generally a great upgrade, and this build from [DJJules] aims to be just that.

It’s a stereo mic setup based on the work of the Office de Radiodiffusion Télévision Française, or ORTF. The ORTF stereo technique defines using two cardioid mics pointing left and right at a seperation of 110 degrees and 17 cm apart, which captures a quality stereo field that also sounds good when presented as a mono mixdown.

The build uses a simple wooden frame to hold two electret mic capsules in the required orientation. They’re wired up to a 3.5mm jack so they can be plugged straight into a mic input on a DSLR or other similarly-equipped camera. Hair curlers covered in faux fur are used as a wind shield for the mics, and gives the build a properly professional look. The frame is also given a mount so it can easily sit on a camera’s cold shoe fitting. Alternatively, a screw mount can also be used.

Good audio is absolutely key to making good content, and having quality mics is definitely what you need to achieve that. We’ve featured some other great DIY mic builds over the years, too. Video after the break. Continue reading “Camera-Mounted Stereo Mic Is Fluffy And Capable”

Walkmp3rson Is An MP3 Player Like Sony Never Made

If you weren’t already well aware, the 90s are like, so hot right now, and that includes cassette tapes for some reason. (Even though we personally didn’t have a CD player until 1998, they were around as early as 1982.) But if you don’t dig the quality of cassettes, or if you’d just rather carry around more than 45-120 minutes worth of music, than [John Edgar Park]’s Walkmp3rson is definitely the build for you. That’s pronounced ‘Walkperson’, as in a 21st century MP3-based update of the classic Walkman.

Inside this amazing 3D printed enclosure, you’ll find an Adafruit Feather RP2040 controlling the screen, handling input from the rotary encoder and those sweet mechanical keyswitches, and of course, playing audio files from SD cards through the amplifier breakout board. And no, this isn’t just another MP3 player — well, it kind of is, but the presentation really goes a long way here.

There are tons of retro-modern nods, like the cassette reel animation that plays on the TFT screen, the boxy enclosure, and the fact it involves physical media. Oh yes — you get to insert an SD card whenever you want to change albums/discographies/genres/whatever. In fact, this would be a great use of older, smaller SD cards. You could go all out and make tiny album art to slip inside those milky plastic cases. Check out the brief demo video after the break.

Looking to play your tunes on a microcontroller, but not a fan of the Walkman aesthetic? In June we covered a similar audio player powered by the ESP32 that does an uncanny impersonation of a portable tape deck that you might be interested in.

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How The BBC (Still) Sends Audio To Transmitter Sites

Running a radio station is, on the face of it, a straightforward technical challenge. Build a studio, hook it up to a transmitter, and you’re good to go. But what happens when your station is not a single Rebel Radio-style hilltop installation, but a national chain of transmitter sites fed from a variety of city-based studios? This is the problem facing the BBC with their national UK FM transmitter chain, and since the 1980s it has been fed by a series of NICAM digital data streams. We mentioned back in 2016 how the ageing equipment had been replaced with a modern FPGA-based implementation without any listeners noticing, and now thanks to [Matt Millman], we have a chance to see a teardown of the original 1980s units. The tech is relatively easy to understand from a 2020s perspective, but it still contains a few surprises.

In each studio or transmitter site would have been a 19″ rack containing one of these units — a card frame with a collection of encoder or decoder cards. These are all custom-made by the BBC’s engineering department to a very high standard, and use period parts such as the familiar Z80 microprocessor and some Philips digital audio chips, which followers of high-end consumer audio may recognize. As you’d expect for a mission critical device, many of the functions are duplicated for redundancy, with their outputs compared to give warning of failures.

The surprise comes in the NICAM encoder and decoder — it’s a custom LSI chip made exclusively for the BBC. This indicates the budget available to the national broadcaster, and given that these units have in some cases been working for over 35 years, we’re guessing that the license payers got their money’s worth.

You can read about the original switch-over in 2016, and a little more about NICAM, too.

Get Your Raspberry Pi Jamming With MuPiBox

Over the years we’ve seen a lot of Raspberry Pi boards pushed into service as media players. In fact, second to emulating old game consoles, that’s probably the Pi’s most common vocation when it comes to DIY builds. But despite the popularity of this particular use case, it seems like each one has had to reinvent the wheel.

Perhaps there’s where MuPiBox fits in. Developed by [Eric Gerhardt] and [Olaf Split] with the assistance of [Andreas Lippmann] and [Andrew Frericks], this project aims to turn everyone’s favorite Linux single-board computer into everyone’s favorite music player. MuPiBox provides not only the software to run your new high-tech boom box, but it even standardizes the hardware design and provides a 3D printable enclosure — though naturally there’s still room for interpretation if you don’t want yours to look exactly like all the others.

Your MuPiBox can look like whatever you want.

At the very minimum you’ll need a Raspberry Pi, a HifiBerry MiniAmp, and a speaker, though the instructions also recommend you invest in a Pimoroni OnOff SHIM (or wire up something comparable) to facilitate more graceful shutdowns. For the best experience you’ll also want a five inch Waveshare touch screen display and a USB power bank so your beats can go mobile.

The video below shows off the polished stock GUI, which is simple enough that even children should be able to navigate around and find their favorite tracks. Which is good, especially since it’s in German. The video also shows off some advanced setup features so you don’t have to pull the SD card out of the Pi just to change the WiFi network it’s attached to. There’s also a web interface that you can access from other devices on the network.

It’s a slick project, and we really like the aesthetics of the 3D printable enclosure. But even if you don’t want to replicate the project exactly, there’s certainly components here which could be utilized in your own Pi media center build.

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Remove A Speaker’s Voice From A Recording Using Ultrasound

What if you could effectively prevent someone from recording your voice? This is the focus of a study by Guo et al. (2022) at Michigan State University, in which they use a dynamically calculated audio signal that effectively cancels out one’s voice in a recording device. This relies on an interesting aspect of certain micro-electro-mechanical system (MEMS) microphones, which are commonly used in smartphones and other recording devices.

Pressure sensitivity of a MEMS microphone. (credit: Brian R. Elbing)
Pressure sensitivity of a MEMS microphone. (credit: Brian R. Elbing)

A specially crafted ultrasound signal sent to the same microphone which is recording one’s voice can result in the voice audio signal being gone on the final recording. The approach taken by the authors involves using a neural network that is trained on voice samples of the person (“Bob”) whose voice has to be cancelled. After recording Bob’s voice during a conversation, the creatively named Neurally Enhanced Cancellation (NEC) system determines the ultrasound signal to be sent to the target recording device. Meanwhile the person holding the recording device (“Alice”) will still perceive Bob’s voice normally.

As ultrasound is highly directional, the system can only jam a specific microphone and wouldn’t affect hidden microphones in a room. As noted by the authors, it is possible to do general microphone jamming using other systems, but this is legally problematic, which should not be an issue with their NEC system.

Thanks to [JohnU] for the tip!

Build Your Own 3D Printed Bluetooth Headphones

A few years back, [Shannon Ley] wondered how hard it would be to build a pair of Bluetooth headphones from scratch. Today, we have our answer. The Homebrew Headphones website is devoted to just one thing: explaining how you can use common components and some 3D printed parts to build an impressively comprehensive pair of wireless headphones for around $50 USD.

The headphones pair a CSR8645 Bluetooth audio receiver with a TP4056 USB-C charging module, a 500 mAh LiPo pouch battery, a pair of Dayton Audio CE38MB-32 drivers, and replacement ear covers designed for the Bose QuietComfort QC15. Some perfboard, a couple buttons, a resistor, and an LED round out the parts list.

All of the components fit nicely into the meticulously designed 3D printed frame, and assembly is made as simple as possible thanks to an excellent step-by-step guide. It’s all so well documented that anyone with even basic soldering experience should be able to piece it together without too much fuss.

Of course, these aren’t the first 3D printed headphones we’ve ever seen. But the quality of the documentation and attention to detail really make these stand out.