Up Close and Personal with a MEMS Microphone https://hackaday.com/2023/12/20/up-close-and-personal-with-a-mems-microphone/ #microelectromechanicalsystems #scanningelectronmicrophone #digitalaudiohacks #microfabrication #microphone #Teardown #etching #silicon #MEMS #sem

CT Scanner Reveals The Difference Between Real and Fake AirPods https://hackaday.com/2023/11/29/ct-scanner-reveals-the-difference-between-real-and-fake-airpods/ #digitalaudiohacks #Airpods #CTScan

Noise Cancelling isn’t as Easy as You’d Think https://hackaday.com/2023/11/28/noise-cancelling-isnt-as-easy-as-youd-think/ #digitalaudiohacks #noisecanceling #microphone #headphone

After MEMS Microphones, MEMS Speakers Enter The Market https://hackaday.com/2023/11/15/after-mems-microphones-mems-speakers-enter-the-market/ #digitalaudiohacks #MEMSspeaker #MEMS

Stream Vinyl To Your Sonos Without The Financial Penalty https://hackaday.com/2023/11/13/stream-vinyl-to-your-sonos-without-the-financial-penalty/ #digitalaudiohacks #RaspberryPi #raspberrypi #streaming #audio #vinyl

The Best-Sounding Walnut You’ll Hear Today https://hackaday.com/2023/11/02/the-best-sounding-walnut-youll-hear-today/ #deadbugconstruction #digitalaudiohacks #bluetoothspeaker #bluetooth #deadbug #walnut

Exploring Hidden Lyrics on 1990s DCC Audio Tapes https://hackaday.com/2023/09/11/exploring-hidden-lyrics-on-1990s-dcc-audio-tapes/ #homeentertainmenthacks #ReverseEngineering #digitalaudiohacks #digitalaudio #metadata #lyrics #audio #ITTS #dcc

Fixing Some More of Apple’s Design Mistakes https://hackaday.com/2023/08/02/fixing-some-more-of-apples-design-mistakes/ #digitalaudiohacks #RepairHacks #Applerepair #AirPodsPro #bluetooth #Airpods #AirPod #repair #apple #audio

Planar Speaker Build Uses Hard Drive Magnets https://hackaday.com/2023/07/15/planar-speaker-build-uses-hard-drive-magnets/ #digitalaudiohacks #planarspeakers #speakers #foil

Faux-Retro “Tape” Player Runs on ESP32 and 80s Vibes https://hackaday.com/2022/06/23/faux-retro-tape-player-runs-on-esp32-and-80s-vibes/ #digitalaudiohacks #microcontrollers #audiobook #cherrymx #1980s #esp32 #retro #i2s

An MP3 Player That Gives Off Nintendo Vibez

We're definitely pretty fond of the DIY MP3 players here at Hackaday, but we don't think we've seen one like CartridgeMP3 from [jpet26] before.

All the electrical components are what we've come to expect. [jpet26] uses the popular VS1053 decoder to read MP3 files stored on an SD card. He also includes a potentiometer for adjusting volume, a USB C port for power and programming, a headphone jack for the audio output, a general-purpose status LED, and an on/off switch.

But what really caught our attention is the form factor [jpet26] selected for his MP3 player. Though the MP3 files are stored on an SD card, he uses a cartridge interface, similar to that of a Nintendo 64 or Game Boy of yesteryear, to choose which MP3 to play from the SD card. The cartridge interface is tied to a few GPIO pins and by reading the status of each pin, the device determines which MP3 to select.

You could say that the cartridge is a little unnecessary, and we wouldn't argue with you. The cartridge doesn't actually store the MP3 files, the SD card does. It might make a bit more sense if the cartridge housed the SD card itself with a few select MP3s stored on the card. That would be a quirky way of sharing your favorite playlists with your friends. So, yeah some clumsy handshaking there, but who isn't guilty of that from time to time? We like it and thought you might appreciate it as well.

Cool MP3 player, [jpet26]! May we suggest a speaker for V2? And maybe some flex cables.

#digitalaudiohacks #audio #codec #mp3 #nintendo #synthesizer #vs1053

Desktop Soundbar Is Ideal for PC Use

Soundbars are a rather strange category of speaker, most typically used with televisions to add some punch that the drivers crammed into a flatscreen TV simply can't match. [Matt] of DIY Perks wanted a soundbar that was better suited to use on a computer desk rather than in a loungeroom, and set about creating one.

Regular soundbars aren't great for a computer desk as they tend to deliver sound directed at one's chest rather than one's ears. [Matt]'s design instead angles its speakers slightly upwards, aimed at the user's head as it should be. The build uses reclaimed wooden flooring for a cheap source of pretty wood that isn't as ugly or flaky as MDF.

The design acts as a monitor stand and keyboard hutch, raising the screen to a comfortable height for viewing. The speakers themselves are in acoustic enclosures mounted on either side, also helping to provide good stereo separation. A subwoofer is also built into the shelf to add some bass response, with an impressively-neat bass chamber design. Finished off with some LED lights and a USB hub, the design delivers great sound along with a lovely desk environment for getting work done.

[Matt] does love a nice DIY build; his water-cooled outdoor TV is a particular delight. Video after the break.

#computerhacks #digitalaudiohacks #computerspeakers #soundbar #surroundsound

Low-Cost, Two-Channel Scriptable Waveform Generator

Microcontroller addict [Debraj] decided to make his own programmable sine wave generator, and was able to put it together for under $40 USD. Other than low-cost, his list of requirements was as follows:

• Dual sine wave output, synchronized
• Frequency, Amplitude, and Phase control
• Low harmonics under 1 MHz
• Scriptable via Python

The heart of the project is the Analog Devices AD9833, a complete Direct Digital Synthesis (DDS) waveform generator system on a chip. If you've ever rolled your own DDS using discrete ICs or in an FPGA, you can appreciate the benefit of squeezing the phase accumulator, sine lookup table, DAC, and control logic all into a single ten-pin package. [Debraj] uses AD9833 modules from the usual online vendors for a few dollars each. He synchronizes the generators by disconnecting the reference crystal on the second module and driving it from the first one. The remaining specifications are met by the inherent characteristics of the DDS system, and the scriptable interface is accomplished with an Arduino controlling the AD9833 chips and two programmable gain amplifiers (MCP6S31). We like the confidence that [Debraj] displays by sketching the initial circuit diagram with a ball-point pen -- check out the sketch and the final pictorial schematic in the video below the break.

This is a good example of combining off-the-shelf modules to quickly build a project. This approach is great for one-off builds or as a proof-of-concept test bed that can later be spun onto a custom PCB. Another reason to use modules these days is that the modules are often in-stock but the chips are unobtainable. Though it appears [Debraj]'s only needs one of these generators, it would be an easy board to layout and build -- if you can buy the parts.

#digitalaudiohacks #toolhacks #ad9833 #dds #functiongenerator #lowcost

Bend It Like (Sonar) Beacon With A Phased Array

Ultrasonic transducers are incredible, with them you can detect distances, as well as levitate and peer through objects. They can emit and receive ultrasonic soundwaves (typically above 18khz) and just like all waves, they can be steered via a phased array. [Bitluni] was trying to accurately measure distances but found the large field of view of the sensor was just too imprecise, so he made a phased array of transducers.

The inspiration came from a Hackaday Supercon talk from 2019 about phased arrays. [Bitluni] walks through an excellent explanation of how the array works with a bucket of water and his finger, as well as a separate simulation. By changing the phase offset of the different array members, the beam can effectively be steered as interference muffs the undesired waves. Using a set of solenoids, he created a test bench to validate his idea in a medium he could see; water. The solenoids fire a single pulse into the water creating a wave. You can see the wave move in the correct direction in the water, which validates the concept. A simple PCB sent off to a fab house with a stencil offers a surface to solder the transducers and drivers onto. An ESP32 drives the 8 PWM signals that go to the transmitters and reads in the single receiver via a small amplifier. Still not content to let the idea be unproven, he sets up the receiver on his CNC gantry and plots the signal strength at different points, yielding beautiful "heat maps."

It sweeps a 60-degree field in front of it at around 1-3 frames per second. As you might imagine, turning sound wave reflections into distance fields is a somewhat noisy affair. He projects the sonar display on top of what we can see in the camera and it is fun to see the blobs line up in the correct spot.

We noticed he built quite a few boards, perhaps in the future, he will scale it up like this 100 transducer array? Video after the break.

#digitalaudiohacks #microcontrollers #phasedarray #ultrasonic #ultrasonicarray

Immersive Stereo Sound Recording With This Binaural Microphone

Sound recording has been a consumer technology for so long now that it is ubiquitous, reaching for a mobile device and firing up an app takes only an instant. Anyone who takes an interest in audio recording further will find that while it's relatively straightforward to make simple recordings. But, as those among you who have fashioned a pair of Shure SM58s into an X configuration with gaffer tape will know, it can be challenging to create a stereo image when recording outside the studio. In the quest to perfect this, [Kevin Loughin] has created a binaural microphone, which simulates a human head with microphones placed as ears to produce ambient recordings with an almost-immersive stereo image.

Commercial binaural microphones can cost thousands of dollars, but this one opts for a more budget design using an off-the-shelf mannequin head sold for hairdressers. It's filled with high-density foam, and in its ears [Kevin] placed 3D-printed ear canals with electret microphone capsules. On the back goes a battery and a box for the bias circuitry.

The results as you can hear in the video below the break are impressive, certainly so for the cost. It's not the first such microphone we've shown you, compare it with one using a foam-only head.

#digitalaudiohacks #audio #binauralaudio #microphone