We love it when someone takes an idea they’ve seen on Hackaday and runs with it, taking it in a new and different direction. That’s pretty much what we’re here for, after all, and it’s pretty gratifying to see projects like this wooden ribbon microphone come to life.
Now, we’re not completely sure that [Maya Román] was inspired by our coverage of [Frank Olson]’s homage to the RCA Model 44 studio mic rendered in walnut veneer, but we’re going to pat ourselves on the back here anyway. The interesting thing with [Maya]’s build is that she chose completely different materials and design styles for her project. Where [Frank] built as much of his mic from wood as possible, [Maya] was fine with a mixed media approach — CNC-milled plywood for the case and stand, laser-cut acrylic for the ribbon motor frame, and 3D-printed pieces here and there as needed. The woven brass cloth used as a windscreen is a nice detail; while the whole thing looks — and sounds — great, we think it would be even better with a coat of dark stain to contrast against the brass, as well as a nice glossy coat of polyurethane.
The video below shows the whole design and build process, which was a final project for [Maya]’s audio production class this semester at college. Here’s hoping that it got as good a grade as we would give it.
Few things get a Hackaday staffer excited like bunches of tiny LEDs. The smaller and denser the better, any form will do as long as we can get a macro shot or a video of a buttery smooth animation. This time we turn to [Sawaiz Syed] and [Open Kolibri] to deliver the brightly lit goods with the minuscule HALO 90 reactive LED earrings.
The HALO 90’s are designed to work as earrings, though we suspect they’d make equally great brooches, hair accessories, or desk objects. To fit this purpose each one is a minuscule 24 mm in diameter and weighs a featherweight 5.2 grams with the CR2032 battery (2.1 g for the PCBA alone). Functionally their current software includes three animation modes, each selectable via a button on device; audio reactive, halo (fully lit), and sparkle. Check out the documentation for details on expected battery life in each mode, but suffice to say that no matter what these earrings will make it through a few nights out.
In terms of hardware, the HALO 90’s are as straightforward as you’d expect. Each device is driven by an STM8 at its maximum 16MHz which is more than fast enough to keep the 90 charliplexed 0402 LEDs humming along at a 1kHz update rate, even with realtime audio processing. In fact the BOM here is refreshingly simple with just 8 components; the LEDs, microcontroller and microphone, battery holder and passives, and the button. [Sawaiz] even designed an exceptionally slick case to go with each pair of earrings, which holds two HALO 90’s with two CR2032’s and includes a magnetic closure for the most satisfying lid action possible.
As with some of his other work, [Sawaiz] has produced a wealth of exceptional documentation to go with the HALO 90’s. They’re available straight from him fully assembled, but with documentation this good the path to a home build should be well lit and accessible. He’s even chosen parts with an eye towards long availability, low cost, and ease of sourcing so no matter when you decide to get started it should be a snap.
It was difficult to choose just a few images from [Sawaiz]’s mesmerizing collection, so if you need more feast your eyes on the expanded set after the break.
Carbohydrate foams derived from dead trees are not the first material that springs to mind when considering building audio equipment. But really, there’s no reason not to explore new materials for jobs normally reserved for metal or plastic, and when pulled off right, as with this wooden ribbon microphone, the results can both look and sound great.
To be fair, there are plenty of non-wood components in [Frank Olson]’s replica of a classic RCA model 44 microphone. After all, it’s hard to get wood to exhibit the electromagnetic properties needed to turn acoustic energy into electric currents. But that doesn’t mean that wood, specifically walnut veneer, isn’t front and center in this design. [Frank] worked with thin sheets of veneer; cut into shape with a commercial vinyl cutter and stacked up with alternating grains, the wood was glued up with copious cyanoacrylate adhesive to form a plywood of sorts. The dogbone-shaped body was fitted with two neodymium magnets, leaving a gap just wide enough for the microphone’s ribbon diaphragm. That was made from a thin piece of aluminum foil that was corrugated using a DIY crimp roller. Suspended between the magnets and connected to leads, the mic element was adorned with a wood and fabric windscreen and suspended from elastic bands in a temporary frame for testing. The narration on the video below was recorded with the mic, which sounds quite nice to our ears.
We’ve seen ribbon microphones before, as well as wooden microphones, but this is the first time we’ve seen a wooden ribbon microphone. It looks as though [Frank] has more work he wants to do to finish it off properly, and we eagerly await the finished product.
Since we’ve started inviting them into our homes, many of us have began casting a wary eye at our smart speakers. What exactly are they doing with the constant stream of audio we generate, some of it coming from the most intimate and private of moments? Sure, the big companies behind these devices claim they’re being good, but do any of us actually buy that?
It seems like the most prudent path is to not have one of these devices, but they are pretty useful tools. So this hardware mute switch for an Amazon Echo represents a middle ground between digital Luddism and ignoring the possible privacy risks of smart speakers. Yes, these devices all have software options for disabling their microphone arrays, but as [Andrew Peters] relates it, his concern is mainly to thwart exotic attacks on smart speakers, some of which, like laser-induced photoacoustic attacks, we’ve previously discussed. And for that job, only a hardware-level disconnect of the microphones will do.
To achieve this, [Andrew] embedded a Seeeduino Xiao inside his Echo Dot Gen 2. The tiny microcontroller grounds the common I²S data line shared by the seven (!) microphones in the smart speaker, effective disabling them. Enabling and disabling the mics is done via the existing Dot keys, with feedback provided by tones sent through the Dot speaker. It’s a really slick mod, and the amount of documentation [Andrew] did while researching this is impressive. The video below and the accompanying GitHub repo should prove invaluable to other smart speaker hackers.
Google’s fledgling Stadia service leverages the Chrome ecosystem to deliver streamed PC games on mobile devices, web browsers, and TVs. While not strictly required, the company even offers a dedicated Stadia controller that connects directly to the streaming servers over its own WiFi connection to reduce overall system latency. Of course, being a Google product, the controller has a tiny microphone that’s always listening in for interacting with the voice assistant.
[Heikki Juva] didn’t like the privacy implications of this, but unfortunately, there appears to be no way to turn off this “feature” in software. He decided the most expedient solution would be to simply remove the microphone from the controller, but it turns out there was a problem. By researching previous teardowns, he found out that it’s nearly impossible to take the controller apart without damaging it.
Getting close to the target.
So [Heikki] came up with a bold idea. Knowing roughly the position of the microphone, he would simply drill through the controller’s case to expose and ultimately remove the device. The operation was complicated by the fact that, from the teardown video he saw, he knew he’d also have to drill through the PCB to get to the microphone mounted to the opposite side. The only bright spot was that the microphone was on its own separate PCB, so physically destroying it probably wouldn’t take the whole controller out with it.
Now we don’t have to explain why drilling into a gadget powered by an internal lithium-ion battery is dangerous, and we’re not necessarily vouching for the technique [Heikki] used here. But when presented with a sealed unit like this, we admit there weren’t a lot of good options. The fact that the user should have to go to such ridiculous lengths to disable the microphone in a game controller is a perfect example of why we should try to avoid these adversarially designed devices, but that’s a discussion for another time.
In the end, with a steady and and increasingly larger bits, [Heikki] was able to put a 7 mm hole in the back of the Stadia controller that allowed him to extract the microphone in one piece. Removing the microphone seems to have had no adverse effect on the device as, surprisingly enough, it turns out that a game controller doesn’t actually need to listen to the player. Who knew?
A wise senator once noted that democracy dies with thunderous applause. Similarly, it’s also how privacy dies, as we invite more and more smart devices willingly into our homes that are built by companies that don’t tend to have our best interests in mind. If you’re not willing to toss all of these admittedly useful devices out of the house but still want to keep an eye on what they’re doing, though, [Nick Bild] has a handy project that lets you keep an eye on them when they try to access the network.
The device is built on a Raspberry Pi that acts as a middle man for these devices on his home network. Any traffic they attempt to send gets sent through the Pi which sniffs the traffic via a Python script and is able to detect when they are accessing their cloud services. From there, the Pi sends an alert to an IoT Arduino connected to an LED which illuminates during the time in which the smart devices are active.
The build is an interesting one because many smart devices are known to listen in to day-to-day conversation even without speaking the code phrase (i.e. “Hey Google” etc.) and this is a great way to have some peace-of-mind that a device is inactive at any particular moment. However, it’s not a foolproof way of guaranteeing privacy, as plenty of devices might be accessing other services, and still other devices have even been known to ship with hidden hardware.
A yogurt lid and embroidery hoop are key components in building this microphone. It’s a super low tech, entry-level project to get into “found sound” and exactly what is needed to start hacking around in the audio world. This workshop presented by Helen Leigh and Robyn Hails shows you how to build a simple microphone and use it as the electronic gateway to all kinds of audio shenanigans.
Key to this build are the piezo element and an amp to process the signals it generates. All other materials are common around most households, but put them together as shown in this live hands-on seminar from the 2020 Hackaday Remoticon, and I think you’ll surprise yourself with how good the thing sounds!
