Headphone Amp Features A Tiny CRT

July 7, 2015 by Adam Fabio 40 Comments

[ErikaFluff] needed an amp for her Grado open cans. Rather than build yet another boring black box, she built what may be the most awesome headphone amp ever by adding a tiny CRT which displays the current audio waveform. She packaged all this up in a customized Hammond box which makes it look like it just rolled off the line from some audiophile studio.

The amplifier in this case is based upon the CMoy, a common headphone amp design. [ErikaFluff] added a MOSFET on the output to drive his relatively low impedance (32 ohm) Grado headphones with reasonable volume. The CRT is from an old video camera viewfinder. Before LCDs were advanced and cheap enough to include in video cameras, CRTs were the only show in town. These tiny black and white screens use high voltage to scan an electron beam across a phosphor screen just like their bigger brethren.

Since she was going with an oscilloscope style vector scan rather than the raster scan the screen electronics were originally designed for, [ErikaFluff] had to create her own horizontal and vertical deflection circuits. Horizontal scan is created by a 555 timer generating a sawtooth wave at 75 Hz. Vertical deflection is via an LM386 driving a hand wound impedance matching transformer. The high voltage flyback transformer and its associated driver circuit were kept from the original CRT, though repackaged to make them as small as possible.

You might think that having a few thousand volts next to a sensitive audio amplifier would cause some noise issues. We also worried a bit about shorts causing unexpected shock treatments through the wearer’s ears. [ErikaFluff] says there is no need to for concern — the signal is fed to the CRT circuit through optocouplers. The audio circuit is also electrically split from the CRT and runs on a virtual ground. Judicious amounts of shielding tape keeps the two circuits isolated.

This may not be the most practical project, but we think it’s pretty darn cool. The response over on Reddit’s electronics subreddit seems to be positive as well. We hope [ErikaFluff] is sitting down when this post gets published!

Cyclist Pulled Over For Headphones Builds Neighborhood Shaking Bicycle Boombox

April 13, 2015 by Mike Szczys 86 Comments

Riding around with headphones on is not the safest of things; those people ~~are trying to~~ could hit you! [Victor Frost] was actually pulled over for doing it. Although the bicycle police didn’t ticket him, they did push him over the edge to pursuing a compromise that lets him listen to tunes and perhaps still hear the traffic around him.

The build puts 200 Watts of audio on his rear luggage rack. He used a couple of file totes as enclosures, bolting them in place and cutting one hole in each to receive the pair of speakers. The system is powered by two 6V sealed lead-acid batteries which are topped off by a trickle-charger when the bike is parked.

Looking through this log we almost clicked right past this one. It wasn’t immediately apparent that this is actually version four of the build, and these are completely different spins each time. The top-down view of plastic-tacklebox-wrapped-v3 is sure to make you grin. Video overviews of the first two versions are linked in [Victor’s] details section of the project page linked at the top of this post. The progress is admirable and fun time digging through. They’re all quite a bit different but bigger, better, and more self-contained with each iteration.

Okay, okay, maybe this isn’t going to shake the neighborhood… until he adds a Bass Cannon to it.

SNES Headphones Cry For Bluetooth Has Been Answered

March 26, 2015 by Rich Bremer 3 Comments

A year and a half ago we ran a post about a SNES controller modified into a pair of headphones. They were certainly nice looking and creative headphones but the buttons, although present, were not functional. The title of the original post was (maybe antagonistically) called: ‘SNES Headphones Scream Out For Bluetooth Control‘.

Well, headphone modder [lyberty5] is back with a vengeance. He has heeded the call by building revision 2 of his SNES headphones… and guess what, they are indeed Bluetooth! Not only that, the A, B, X and Y buttons are functional this time around and have been wired up to the controls on the donor Bluetooth module.

To get this project started, the SNES controller was taken apart and the plastic housing was cut up to separate the two rounded sides. A cardboard form was glued in place so that epoxy putty could be roughly formed in order to make each part completely round. Once cured, the putty was sanded and imperfections filled with auto body filler. Holes were drilled for mounting to the headband and a slot was made for the Bluetooth modules’ USB port so the headphone can be charged. The headphones were then reassembled after a quick coat of paint in Nintendo Grey. We must say that these things look great.

If you’d like to make your own set of SNES Bluetooth Headphones, check out the build video after the break.

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Wireless Helmet Speakers Receive A+ For Distracting Wearer

February 6, 2015 by Rich Bremer 27 Comments

What could be better than cruising around town on your fave scooter? Cruising around town on your fave scooter listening to some cool tunes, of course! [sswanton] was enrolled in an Industrial Design course and was tasked with creating a wireless radio project for a specific user (of his choice). He decided to add some wireless speakers to a motorcycle helmet and design a handlebar-mounted radio.

[sswanton] started out by disassembling the ultra-inexpensive, old-school, battery-powered Sony ICF-S22 radio specified by the class. The stock case was discarded as he would have to make a new one that fits onto the bike’s handlebars. Plywood makes up majority of the frame while the cover is black acrylic. Getting the acrylic bent required heating to 160 degrees so that it could be bent around a form [sswanton] created specifically for this project. A few cutouts in the case allows the rider to access the volume and tuning knobs.

The speakers added to the helmet were from wireless headphones and came with a matched transmitter. The transmitter was removed from it’s unnecessarily large case, installed in the radio’s newly created enclosure and connected to the radio’s headphone output. Situating the headphone components in the ideal locations of the helmet required that the headphones be disassembled. The speakers were placed in the helmets ear cups. Part of the original headphone case and some control buttons were mounted on the outside of the helmet for easy access. The wires connecting the components had to be extended to reconnect the now spread-out parts.

In order to hear that sweet music all the rider needs to do is turn on the headphones and radio. Check this out to see some more helmet speakers, this time a little more wacky.

DIY USB Stereo Headphone Amplifier

January 22, 2015 by Brian Benchoff 26 Comments

The biggest and best audiophile projects are usually huge tube amps, monstrous speaker cab builds, or something else equally impressive. It doesn’t always have to be that way, though, as [lowderd] demonstrates with a tiny DIY USB DAC build that turns a USB port into a headphone output.

In the Bad Old Days™ putting a DAC on a USB bus would require some rather fancy hardware and a good amount of skill. These days, you can just buy a single chip USB stereo DAC that still has very good specs. [lowderd] used the TI PCM2707 USB DAC, a chip that identifies as a USB Audio Class 1.0 device, so no drivers are needed for it to work in either Windows or OS X.

The circuit fits on a tiny PCB with a USB port on one side, a headphone jack on the other, and the chip and all related components in between. There are some pins on the chip that allow for volume, play/pause. and skip, but these pins were left unconnected for sake of simplicity.

The board was fabbed up at OSH Park, and the second revision of the case laser cut out of bamboo and acrylic by Ponoko. It’s a great looking little box, and something that fits right inside [lowderd]’s headphone case.

Adding Bluetooth And A Lightning Connector To Beats Pro Headphones

July 30, 2014 by Brian Benchoff 42 Comments

Beats

Not wanting to wait for Apple to step up their game and complete their purchase of Beats headphones, [Carnivore] decided he wanted his own pair of Apple-compatible Beats cans with Bluetooth. He created something that will probably be for sale in the Apple store come Christmas: a pair of Beats Pro headphones with Bluetooth and a Lightning connector for charging.

[Carnivore] liked the sound of his Beats Pro headphones but hated the wires. After disassembling the headphones, he carefully rewired the speakers with smaller gauge wire, added a small Bluetooth module and battery, and sealed everything back up.

There are a few interesting bits to this build – by getting rid of all external wires, [Carnivore] was left with a few holes in the headphones. These were a perfect place to add a 3D printed mount for the power button and the Lightning adapter taken from an Apple Lightning extension connector.

Thanks [Tony] for the tip!

Block Noise, Listen To Music

May 4, 2014 by Rich Bremer 37 Comments

Noise Blocking headphones made from industrial earmuffs

Noise-Cancelling Headphones actively cancel external sounds so the listener can hear their media without distraction. They do this by taking external sound waves from an on-board microphone, inverting the audio signal and mixing that with the media audio. The outside sounds and their inverses cancel each other out before reaching the listener’s ears. There is one downside to these types of noise-cancelling headphones, they are very expensive.

[Mike] works in a wood shop and didn’t want to pony up the hundreds of dollars it would cost for a pair of noise-cancelling headphones, let alone having such an expensive electronic device in a dusty workshop. The solution? Make some headphones that will block out the noise but still allow the comfortable listening of music. This project is simple but effective; inexpensive headphones taken apart and installed in a pair of Industrial Ear Muffs. If you’d like to make your own, [Mike] gives step by step on the above link.

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