Cheap DIY Mic Sounds (And Looks) Damn Good

November 6, 2021 by Adam Zeloof 30 Comments

As any musician, podcaster, or youtuber will be quick to tell you, there’s no substitute for a good microphone. They’ll also be quick to tell you all about their favorite microphone, why it’s better than all the others, and how much it cost (oh, and how round it sounds, whatever that means). But what if you could build your own that sounds as good, if not better, and do it for only $30?

That’s what [Matt] from DIY Perks set out to discover when he built his DIY USB-C Microphone. He was able to source the same microphone capsule that can be found in his high-end, $600 CAD E100S, and built a simple pre-amplifier that bumps its quiet output up to line-level. He even connected it to the mic module with some custom cable made from two tiny enameled wires that won’t transmit bumps and vibrations, wrapped inside desoldering braiding which acts as a shield. He fed the output from the pre-amp into a cheap USB audio interface and voilà! — top-notch sound for next to nothing. Make sure you check out the video below to hear a comparison between the mic and its professional counterparts.

Of course, sounding good isn’t quite enough. [Matt] wasn’t satisfied until the piece looked the part as well, which is why he encased the mic module in custom-bent brass mesh shielding and tubing (which also helps to reduce electrical interference). The brass cage sits suspended via rubber o-rings on a beautiful bent brass mount, which sits atop an articulated brass arm of [Matt]’s own design. Finally, the arm is mounted to a wood and brass enclosure that also serves to house the electronics.

And, in true open-source fashion, the video description is full of links to parts, schematics, and templates in case you want to build one of these beauties for yourself. Between this fantastic build and this other, super-overkill scratch-built USB microphone we featured earlier in the year, there has never been a better time to make yourself a mic you won’t have to trade your car for.

Thanks to [RichV] and [BaldPower] for the tip!

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SOUL Wants To Process Your Audio

January 29, 2021 by Al Williams 14 Comments

Abstraction is the core of nearly all progress in computing. Unless you are fabricating your own semiconductors and drawing wire, we all create with building blocks ranging from components like CPUs, to operating system functions, to specialized libraries. Just as you wouldn’t want to spend your time deblocking disk records or rendering fonts for output devices, you probably shouldn’t have to think too much about audio data. While there are some powerful audio processing libraries out there, a new embeddable language called SOUL (SOUnd Language) is now in version 1.0 and wants to help you create efficient code for processing audio.

The goal of SOUL is to target a runtime that can run on CPUs, but is better on DSPs. The code aims to be secure and real time with no pointers, garbage collection, and other things that typically interfere with audio processing or security.

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Into The Belly Of The Beast With Placemon

September 17, 2020 by Brian McEvoy 11 Comments

No, no, at first we thought it was a Pokemon too, but Placemon monitors your place, your home, your domicile. Instead of a purpose-built device, like a CO detector or a burglar alarm, this is a generalized monitor that streams data to a central processor where machine learning algorithms notify you if something is awry. In a way, it is like a guard dog who texts you if your place is unusually cold, on fire, unlawfully occupied, or underwater.

[anfractuosity] is trying to make a hacker-friendly version based on inspiration from a scientific paper about general-purpose sensing, which will have less expensive components but will lose accuracy. For example, the article suggests thermopile arrays, like low-resolution heat-vision, but Placemon will have a thermometer, which seems like a prudent starting place.

The PCB is ready to start collecting sound, temperature, humidity, barometric pressure, illumination, and passive IR then report that telemetry via an onboard ESP32 using Wifi. A box utilizing Tensorflow receives the data from any number of locations and is training to recognize a few everyday household events’ sensor signatures. Training starts with events that are easy to repeat, like kitchen sounds and appliance operations. From there, [anfractuosity] hopes that he will be versed enough to teach it new sounds, so if a pet gets added to the mix, it doesn’t assume there is an avalanche every time Fluffy needs to go to the bathroom.

We have another outstanding example of sensing household events without directly interfacing with an appliance, and bringing a sensor suite to your car might be up your alley.

Ondophone On Point

March 28, 2020 by Brian McEvoy 5 Comments

The name Ondophone is a mash-up of two instruments, the Marxophone, and the ondes martenot. From the Marxophone, [Wintergatan] borrows the spring-loaded hammers, which repeatedly strike a string once activated. The ondes martenot loans its Theremin-like sound and ability to lean back on western semi-tone notes. Mating such different instruments requires a team, and much like the name, it produces a splendid blend.

At the left-hand side of the Ondophone, we see the spring-hammer battering away on a steel string whenever the neck moves up or down. Next to it is an Ebow that vibrates a string with an electromagnet and can maintain a note so long as it has power. Hidden within the neck are magnets to demarcate semi-tone locations, so it’s possible to breeze past them for a slide sound or rest on them to follow a tune.

The combination of intermittent hammering and droning lends well to the “creepy” phase of the song, which leads segues to the scope-creep that almost kept this prototype on the drawing board. The video talks about all the things that could have been done with this design, which is a pain/freedom we know well. KISS that Ondophone headline act goodbye.

The ondes martenot is an early electronic instrument, so we’ve some high-tech iterations, and if you haven’t heard what’s possible with a DIY Ebow, we will harp on you.

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What Does Your Necklace Say?

February 17, 2020 by Brian McEvoy 2 Comments

If we write about sound reproduction, there is a good chance we found a home-made amplifier or an upcycled speaker system. In this case, you don’t use your ears to appreciate the sound; you use your hands or eyes. [ElatisEagles] converted an amplitude sound graph into a wearable bead. Even without much background it should be immediately recognizable for what it is. Presumably, they converted a sound wave to vectors, then used the “Revolve” function in Rhino, their software of choice. Sometimes this is called a “lathe” function. Resin printers should be able to build these without supports and with incredible fidelity.

Some tattoos put a sound wave on the skin, and use an app to play it back, but if you want to wear a sound bite from your favorite show and not get branded as the “Pickle Rick” gal/guy at the office, maybe swap out the color and sound wave before it goes stale. We would wear a bead that says, “drop a link in our tip line,” but you can probably think of something more clever.

We have other high-tech ornamentation that leverages motion instead of sound, or how about a necklace that listens instead.

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A Box With A Pocket Sized Boom

December 19, 2019 by Gerrit Coetzee 7 Comments

[Discreet Electronics Guy] sends in his very pocket sized boom box.

One thing we love about [Discreet Electronics Guy]’s projects is how they really showcase that a cool hack is possible without access to 3D printers, overnight PCB services, and other luxuries. Everything in this board is hand made by electronics standards. The board is etched, the vias are wires, and even the case seems to be a modified plastic mint container.

The boombox itself uses an ATiny85 at its core which plays .wav files from an SD card. This is routed through an audio amp which powers two small speakers. We love the volume knob being a board mount potentiometer. The device even features its own small LiON battery pack. If you don’t want to enjoy the deep sound of the two small speakers there’s a headphone jack.

He’s got a great write-up on the circuit design on his website and you can see a video of him presenting the project here or after the break.

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Laser-Based Audio Injection On Voice-Controllable Systems

November 6, 2019 by Pat Whetman 27 Comments

In one of the cooler hacks we’ve seen recently, a bunch of hacking academics at the University of Michigan researched the ability to flicker a laser at audible sound frequencies to see if they could remotely operate microphones simply by shining a light on them. The results are outstanding.

While most Hackers will have heard about ‘The Thing’ – a famous hack where Russian KGB agents would aim a radio transmitter at the great seal in the US embassy, almost none of us will have thought of using lasers shined in from distant locations to hack modern audio devices such as Alexa or Google Assistant. In the name of due diligence, we checked it out on Wikipedia: ‘The Photoacoustic Effect’ , and indeed it is real – first discovered in 1880 by Alexander Bell! The pulsing light is heating the microphone element and causing it to vibrate along with the beam’s intensity. Getting long range out of such a system is a non-trivial product of telescopes, lasers, and careful alignment, but it can be made to work.

Digging deeper into the hack, we find that the actual microphone that is vulnerable is the MEMS type, such as the Knowles SPV0842LR5H. This attack is relatively easy to prevent; manufacturers would simply need to install screens to prevent light from hitting the microphones. For devices already installed in our homes, we recommend either putting a cardboard box over them or moving them away from windows where unscrupulous neighbors or KGB agents could gain access. This does make us wonder if MEMS mics are also vulnerable to radio waves.

As far as mobile phones are concerned, the researchers were able to talk into an iPhone XR at 10 metres, which means that, very possibly, anybody with a hand held ultra violet / infra red equipped flashlight could hack our phones at close range in a bar, for example. The counter-measures are simple – just stick some black electrical tape over the microphone port at the bottom of the phone. Or stay out of those dodgy bars. Continue reading “Laser-Based Audio Injection On Voice-Controllable Systems” →