Maurice Brings Immersive Audio Recording To The Masses

September 7, 2025 by 19 Comments

Immersive audio is the new hotness in the recording world. Once upon a time, mono was good enough. Then someone realized humans have two ears, and everyone wanted stereo. For most of us, that’s where it stopped, but audio connoisseurs kept going into increasingly baroque surround-sound setups — ending in Immersive Audio, audio that is meant to fully reproduce the three-dimensional soundscape of the world around us. [DJJules] is one of those audio connoisseurs, and to share the joy of immersive audio recording with the rest of us, he’s developed Maurice, a compact, low-cost immersive microphone.

Maurice is technically speaking, a symmetrical ORTF3D microphone array. OTRF is not a descriptive acronym; it stands for Office de Radiodiffusion Télévision Française, the fine people who developed this type of microphone for stereo use. The typical stereo ORTF setup requires two cardioid microphones and angles them 110 degrees apart at a distance of 17 cm. Maurice arrays four such pairs, all oriented vertically and facing 90 degrees from one another for fully immersive, 8-channel sound. All of those microphones are thus arrayed to capture sound omnidirectionally, and give good separation between the channels for later reproduction. The mountings are all 3D printed, and [DJJules] kindly provides STLs.

This is the speaker setup you need to get full use of Maurice’s recordings. Now let’s see Paul Allen’s speakers.

Recording eight audio channels simultaneously is not trivial for the uninitiated, but fortunately, [DJJules] includes a how-to in his post. We particularly like his tip to use resistor color coding to identify the XLR cables for different microphone channels. Playback, too, requires special setup and processing. [DJJules] talks about listening on his 7.1.4 stereo setup, which you can find in a companion post. That’s a lot of speakers, as you might imagine.

There are high-end headphones that claim to reproduce an immersive sound field as well, but we can’t help but wonder if you’d miss the “true” experience without head tracking. Even with regular department-store headphones, the demo recordings linked via the Instructable sound great, but that probably just reflects the quality of the individual microphones.

Audio can be a make-or-break addition to VR experiences, so that would seem to be an ideal use case for this sort of technology. Maurice isn’t the only way to get there; we previously focused on [DJJules]’s ambisonic microphone, which is another way to reproduce a soundscape. What do you think, is this “immersive audio” the new frontier of Hi-Fi, or do we call it a stereo for a reason? Discuss in the comments!

Retrotechtacular: Exploring The Moon On Surveyor 1

September 7, 2025 by 13 Comments

Aside from a few stand-out programs — looking at you, Star Trek — by the late 1960s, TV had already become the “vast wasteland” predicted almost a decade earlier by Newton Minnow. But for the technically inclined, the period offered no end of engaging content in the form of wall-to-wall coverage of anything and everything to do with the run-up to the Apollo moon landings. It was the best thing on TV, and even the endless press conferences beat watching a rerun of Gilligan’s Island.

At the time, most of the attention landed on the manned missions, with the photogenic and courageous astronauts of the Mercury, Gemini, and Apollo programs very much in the limelight. But for our money, it was the unmanned missions where the real heroics were on display, starring the less-photogenic but arguably vastly more important engineers and scientists who made it all possible. It probably didn’t do much for the general public, but it sure inspired a generation of future scientists and engineers.

With that in mind, we were pleased to see this Surveyor 1 documentary from Retro Space HD pop up in our feed the other day. It appears to be a compilation of news coverage and documentaries about the mission, which took place in the summer of 1966 and became the first lunar lander to set down softly on the Moon’s surface. The rationale of the mission boiled down to one simple fact: we had no idea what the properties of the lunar surface were. The Surveyor program was designed to take the lay of the land, and Surveyor 1 in particular was tasked with exploring the mechanical properties of the lunar regolith, primarily to make sure that the Apollo astronauts wouldn’t be swallowed whole when they eventually made the trip President Kennedy had mandated back in 1961.

The video below really captures the spirit of these early missions, a time when there were far more unknowns than knowns, and disaster always seemed to be right around the corner. Even the launch system for Surveyor, the Atlas-Centaur booster, was a wild card, having only recently emerged from an accelerated testing program that was rife with spectacular failures. The other thing the film captures well is the spacecraft’s nail-biting descent and landing, attended not only by the short-sleeved and skinny-tied engineers but by a large number of obvious civilians, including a few lucky children. They were all there to witness history and see the first grainy but glorious pictures from the Moon, captured by a craft that seemed to have only just barely gotten there in one piece.

The film is loaded with vintage tech gems, of course, along with classic examples of the animations used at the time to illustrate the abstract concepts of spaceflight to the general public. These sequences really bring back the excitement of the time, at least for those of us whose imaginations were captured by the space program and the deeds of these nervous men and women.

NASA wants to return to the moon. They also want you to help. Turns out making a good landing on the moon is harder than you might think.

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Image Recognition On 0.35 Watts

September 7, 2025 by 23 Comments

Much of the expense of developing AI models, and much of the recent backlash to said models, stems from the massive amount of power they tend to consume. If you’re willing to sacrifice some ability and accuracy, however, you can get ever-more-decent results from minimal hardware – a tradeoff taken by the Grove Vision AI board, which runs image recognition in near-real time on only 0.35 Watts.

The heart of the board is a WiseEye processor, which combines two ARM Cortex M55 CPUs and an Ethos U55 NPU, which handles AI acceleration. The board connects to a camera module and a host device, such as another microcontroller or a more powerful computer. When the host device sends the signal, the Grove board takes a picture, runs image recognition on it, and sends the results back to the host computer. A library makes signaling over I2C convenient, but in this example [Jaryd] used a UART.

To let it run on such low-power hardware, the image recognition model needs some limits; it can run YOLO8, but it can only recognize one object, runs at a reduced resolution of 192×192, and has to be quantized down to INT8. Within those limits, though, the performance is impressive: 20-30 fps, good accuracy, and as [Jaryd] points out, less power consumption than a single key on a typical RGB-backlit keyboard. If you want another model, there are quite a few available, though apparently of varying quality. If all else fails, you can always train your own.

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Theremin-Style MIDI Controller Does It With Lasers

September 7, 2025 by 7 Comments

Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at [aritrakdebnath2003]’s MIDI THEREMIN, we see it works differently, but it does play in the manner of the exotic radio instrument, so we suppose it can use the name.

The MIDI THEREMIN is purely a MIDI controller. It sends note data to a computer or synthesizer, and from there, you can get whatever sound at whatever volume you desire. The device’s brain is an Arduino Uno, and MIDI-out for the Arduino has been a solved problem for a long while now.

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A photo of the PCB from the charging case

Anker Soundcore Space A40 Earbuds Teardown

September 7, 2025 by 3 Comments

Wireless earbuds are notoriously tiny. Want to see inside? [MCH170] did and published a Soundcore Space A40 Teardown.

In this teardown, you’ll see inside the charging case and one of the earbuds. Starting with the case, removing the back cover revealed the charging coil and a few screws holding the PCB in place. Removing the screws allows for removing the coil. The main PCB and the magnets that hold the earbuds in place are then visible. The microcontroller is an SS881Q from Sinhmicro. The back side of the main circuit board has a handful of SMD components, including some status LEDs. The battery is a 13450 with a nominal voltage of 3.72V and a capacity of 800mAh or 2.967Wh.

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Teardown Of A Cheapish EBL Multi-Cell NiMH Charger

September 6, 2025 by 15 Comments

Bottom of the PCB with most of the ICs. (Credit: Brian Dipert, EDN)
Bottom of the PCB with most of the ICs. (Credit: Brian Dipert, EDN)

People think about NiMH cell chargers probably as much as they think about batteries, unless it’s time to replace the cells in whatever device they’re installed in. This doesn’t make a teardown of one of these marvels any less interesting, especially when you can get an 8-bay charger with eight included NiMH cells for a cool $25 brand new. The charger even has USB ports on it, so it’s got to be good. Cue a full teardown by [Brian Dipert] over at EDN to see what lurks inside.

Of note is that [Brian] got the older version of EBL’s charger, which requires that two cells of the same type are installed side-by-side instead of featuring per-bay charging. This is a common feature of cheaper chargers, and perhaps unsurprisingly the charger was struggling with NiMH cells that other chargers would happily charge.

Opening up the unit required hunting for plastic clips, revealing the rather sparse internals. Unsurprisingly, there wasn’t a lot to look at, with the two USB ports apparently wired directly into the AC-to-DC section. There’s a CRE6536 AC-DC power management IC, the full-bridge rectifier and an unmarked 16-pin IC that presumably contains all of the charger logic. On the positive side, the mains-powered charger didn’t catch on fire (yet), but for anyone interested in leaving battery chargers unattended for extended periods of time, perhaps look at a more reputable brand.

Reverse Engineering A (Toy) Fire Engine

September 6, 2025 by 3 Comments

Your kid has a toy remote control fire truck. You have an RTL SDR. See where this is going? [Jacob] couldn’t resist tearing into the why and how of the truck’s remote control protocol.

The entire process began with a basic GNU Radio setup to determine the exact frequency of the signal. Then a little analysis suggested that it might be using amplitude shift keying. That is, the information is in the amplitude of the signal, where one possible amplitude is completely off in some cases.

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