[Dan] had been wanting a pair of Bluetooth headphones for quite a while. Most of the reviews for wireless headphones in the $50-$80 range complained of tinny sound and dropped bass. Nevertheless, he stumbled upon a $20 pair of headphones with similar reviews and realized that he could switch out the driver and make a decent pair of cans.

The donor drivers came from a pair of Sennheiser HD 540 headphones. These are very respectable headphone speakers that cost about what you would expect for pro audio gear. To to get Bluetooth working with the Sennheisers, [Dan] removed the PCB and battery enclosure and attached them to the headband with velcro.

For his build, he had to cut the cable on the Sennheisers and solder them to the Bluetooth board. There was never any danger of ruining a good pair of headphones, though. If he screwed up he was only out a headphone cable. Now [Dan] has a nice pair of Bluetooth headphones that can reproduce bass. Not a bad deal for a $20 pair of headphones.

[Samimy's] latest project is a little strange, but one man’s weird is another man’s wonderful so we’re not about to start criticizing his work. Nope, we’re here to praise the fact that his rotary phone turned reading light and audio amp is very well constructed.

He started by removing the phone housing. Those old enough to have used one of these devices will remember their bulk, and there’s a lot of unused space in both the handset and body housing. [Samimy] started by removing the speaker and microphone from the handset, and drilling a ring of holes to receive white LEDs. The circuit was wired so that lifting the handset turns on the lights.

But he didn’t stop there. A set of speakers and the audio amplifier circuitry from an old tape deck are also hiding inside the base of the phone. If you look closely in the image above you can see that he’s connected his cellphone and is listening to some tunes through the antique hardware. Take a gander at the video after the break to see construction and use of the project.

We know some folks are very upset by the scrapping on vintage hardware, so let’s all observe a moment of silence for this NES controller.

Now that that’s behind us we can live vicariously through [Burger King Diamond's] project. He polished up the NES controller and repurposed it as an enclosure for a portable MP3 player.

His first step was to remove some of the yellowing of the plastic using Retr0brite. He admits it wasn’t bad to start with but now it’s sparkling like new. Next, he started planning how everything would fit in the case. Luckily the MP3 player operates with one AAA battery which leaves plenty of room.

Just above the A and B buttons you can make out an opening that he cut in the case for the MP3 player’s LCD screen. The bezel from the original case works well for cleaning the rough cut opening. The buttons on the controller have been patched into the controls on the MP3 board, and the opening for the controller’s cable now holds the headphone jack. There’s also a USB port mounted next to it for easy file transfers.

The one thing we would like to see is a rechargeable battery so you don’t need to open the case to top off the power. But all in all this is a fantastic build!

Believe it or not, the local Children’s Museum staff was happy that [Bill Porter] left this mess of wires and equipment in one of their offices. It makes up an ambient sound system for a couple of their exhibits. A movie without sound just doesn’t fully entertain, and the same can be said for these exhibits. The ambient sound that goes with a boat room, and a hospital room in the Museum really helps to snag your attention. And [Bill's] material cost came in at just over $200 for both rooms.

He started off by purchasing a speaker, amp, and MP3 breakout board (SparkFun). The speaker mounts in one of the ceiling tiles, with the wire running to a different room where the audio equipment is housed. There were a couple of problems with this; the museum staff forgot to turn on the system, and for all of its expense this only provided one room with audio. Bill figured that since only one speaker was being used he could make an audio file with a different clip on the left and right channel, then feed them to different rooms. He also added that programmable timer so the sounds will turn themselves on and off.

This isn’t the first time we’ve seen hacks end up as museum pieces. Check out this other project that rigs up some interactive telephones.

It’s a fun time to design your own MP3 player, lovingly adding in features to a meticulously crafted user interface. But sometimes you just want a quick and cheap way to add music to a project. [Jeff Ledger] will show you how to do just that using some knock-off hardware from overseas. Instead of a proper breakout board — which can cost a bundle — he used a generic MP3 player acquired for $3 from an eBay seller.

Cracking open the case you’ll see that you actually get a lot for your triad of Washingtons. We know, it may be of questionable quality (see this feature about cheap PSU problems) but we’re not building mission critical hardware now are we? Inside is a rechargeable Lithium battery for use with another project, and a chip-on-board device with attached SD card slot, audio jack, and USB port. The battery inputs are used to solder the MP3 pcb to the power rails on your project. To control the playback, just make connections to the button pads as [Jeff] describes in his post. It sounds like this will work with any MP3 player which runs at either 3.3V or 5V.

In an effort listen to his music on shuffle without the need to touch the volume knob [Mike] build his own automatic volume leveling hardware. He knows what you’re thinking right now: there’s software to do that for you. But building the feature in hardware is a great stepping off point for a project.

He started the prototype using LabVIEW along with a Mobile Studio development board and a Bus Pirate. This project will be a mix of digital and analog components and it’s a bit easier starting off the exploration with these tools rather than jumping right into the AVR code.

The circuit will sample the incoming audio, modify it accordingly, and output the result. The output side is where the Bus Pirate really shines. He’s using some MCP42010 digital potentiometer chips to make the necessary changes to the levels. They communicate via SPI and it’s nice to have the Bus Pirate’s terminal to issue commands without the need to reflash a microcontroller.

[Mike] made a video showing an audio waveform with and without the hardware leveling. Sound quality is still great, and each clip is played at a reasonably comfortable listening level. We’ve embedded that demonstration after the break.

[yotuube=http://www.youtube.com/watch?v=YaEc6_wQ9FM&w=470]

[Matt Keeter] wanted to take his music on the go, and wrote in to share a great looking boombox he built for under $100. His goal was to put something together that could be made in pretty much any hackerspace/fab lab, so his boombox was made using simple materials.

He first modeled the boombox using cardboard, later fabbing it from wood on a laser cutter. The design allows the stereo to be snapped together, though [Matt] says that some joints were glued as an extra precaution. Inside the boombox resides an custom PCB he built which incorporates an ATmega328, an MP3 decoder, and an SD card to store his music.

One feature we really like is the control scheme [Matt] built into the boombox. Each of the capacitive touch buttons are positioned on top of a copper pad, which are wired into the control board. He says that while good in theory, he had a difficult time getting the buttons to work properly, though they seem to do the job well enough.

If you’re looking for a portable music solution and have access to a laser cutter, be sure to check out [Matt’s] page for schematics and firmware.

[form], a new user on the Hack a Day forums, was thinking, “what Christmas present i can send a friend, that would be really annoying?” We think he really hit it out of the park with this one. It’s a modified computer speaker that will play “explicit” audio until the power button is pressed 200 times and the light sensor is covered. When this present is unwrapped, the room will fill with sounds not suitable for children, the elderly, or those with heart conditions.

The build is based around an old powered computer speaker. Six Li-ion batteries from an old laptop provide the power, and a very simple circuit pulls sound off an SD card with the help of an ATtiny45.

The schematic for the build looks easy enough, and like a good builder, [form] included the source and HEX files. Sadly (or thankfully), there is no video of the gag gift in action; probably a good thing, because this seems like a great way to lose a friend.

[Victor] likes to watch movies on his laptop, but the tiny speakers in his machine don’t do [John Williams] and other perfectly fine soundtracks justice. To pump up the jams a little bit, [Victor] got a pair of Trust Mila 2.0 speakers for Sinterklaas. Unfortunately, these speakers were terrible – noise everywhere, tinny output and a brighter-than-the-sun blue LED. These problems were fixed once [Victor] replaced the amplifier in both speakers.

After shopping around for a new power amp to go in each speaker, [Vic] hit upon the MAX9575 3.2 Watt amplifier. This little guy met all of [Victor]‘s requirements. The only problem is that the MAX9575 is only available in a TQFN package.

After a deep breath and much sweat of the brow, both amps found a new home in their respective speakers, deadbug style. It probably would have been easier to etch a PCB, but we’ll give a tip of the hat to [Victor]‘s fine motor skills anyway.

Because of the insane soldering skill demonstrated in the title pic, [Vic] now has a really nice pair of speakers. Check out the demo of the improved speakers after the break.

Baby, it’s cold outside. But that doesn’t stop [Grissini] from listening to some tunes when not indoors. He added headphones to a pair of ear warmers. We guess you could call them ear muffs, which is where the name comes from. But these are the newer type that wrap around the back of your head.

[Grissini] picked up a set of headphones that similarly wrap around the back of your head. After pulling the speakers out of their plastic enclosures he needed a way to soften the sharp edges when they’ll be pressed against your ears. Sugru once again shows its versatility by providing a soft, self-bonding, and moldable surface. The last step is dead simple, as the ear warmers already have a fabric pocket by each ear perfect for accepting the speakers.

Now we need this to go one step further, by making them wireless. We figure hacking in a bluetooth headset board would make it work with your cellphone. Or you could roll your own minimal MP3 board and house it in the part that wraps around your neck.

We’re all familiar with those musical greeting cards. Give the Hallmark store $10, and you have a card with a microcontroller inside that plays one of several songs available. [Jarv] was playing around with translating MIDI tracks to square wave songs with an Arduino earlier, so he decided to see how cheaply he could reproduce these musical cards. The resulting build allows him to put any song he wants in his card and costs less than the Hallmark offering.

The circuit is extremely minimal – just an ATtiny 85, a battery holder, and two piezo speakers for two-voice harmony. After soldering up the battery and speakers, [Jarv] needed a way to get music on his chip. For this, he used MuseScore, a music notation program that allows [Jarv] to merge multiple voices together.

Once the sheet music was cleaned up, [Jarv] used his XML2H Python script that takes MIDI data and spits out frequencies and delays. In the end, [Jarv] spent less than $5 on his greeting card – almost cheap enough to start thinking about musical throwies to complement the batteries, LEDs and magnets on our window flashing.

Check out the video after the break to hear [Jarv]‘s circuit play the theme from Toy Story.

[Grissini] hasn’t had the best of luck when it comes to personal audio players. He estimates that he’s gone through about half a dozen iProducts/iKnockoffs over the years, which ultimately adds up to a lot of money poured right down the drain. Rather than lay down his cold hard cash for yet another music player that would succumb to a dead battery or cracked screen, [Grissini] decided that he would be better off if he built one himself.

His Orange mePod isn’t exactly the most attractive or sleekest music player out there, but [Grissini] says it works like a charm. An Arduino Uno powers the device, and he uses an Adafruit Wave Shield to handle the audio playback. Power is supplied via 4AA batteries which keep the tunes going for a reasonable amount of time, and afford him the ability to swap them out for recharging without much fuss.

The player was encased with some leftover cardboard and wrapped in bright orange duct tape, before being mounted on [Grissini’s] belt. He says he gets plenty of looks when he’s out and about, which you would expect from such a unique design.

Stick around to see a quick video of the audio player in action.

We love looking in on [Simon Inns'] projects, and this must be one of his very best. This is the fifth version of his MIDI-capable stylophone. The gist of the control system is that a conductive keyboard (made of a tinned PCB) is played by making a connection with the tip of a wired stylus — hence the name. The idea comes from the original 1968 Dubreq Stylophone hardware, but [Simon's] not just using the idea. He has his own working original and used it to reverse engineer the circuit design.

When it first came out, the Stylophone had three flavors for Bass, Standard, and Treble audio ranges. They differed only in the choices of passive components used in the circuit. [Simon] built the variations into his design so that they are selectable on one unit. This most recent version connects via USB, allowing you to control MIDI software. But unlike his first four iterations, this also offers MIDI-In capabilities. This makes it possible to control tuning, vibrato, and to drive the Stylophone circuitry from the computer interface. Get a good look at that, and a nostalgic Portal moment, by watching the clip after the break.

If you’re looking for an easier build, you might try this analog standalone version of the Stylophone.

[Peter] was tired of crawling behind his desktop computer to switch between headphones and speakers. We feel his pain, as the headphone port on our computer speakers has its own demonic hum rendering the jack useless to us. His solution was to build this output selector board, then control it via the network.

A relay is responsible for routing the single input to one of two outputs. One output is wired to the normally closed pin on the relay, the other to the normally open pin. The important thing here is to make sure you have a separate audio ground so as not to pick up noise from the rest of the hardware.

What you see above is only the switching circuitry. This is where [Peter] went a little overboard, using an Arduino along with an Ethernet shield to drive the relay via a transistor. For this particular application there must be an easier way. But if you’re working on home automation from your smart phone, this might be just the thing to make your audio setup browser-controlled.

[via Build Lounge]

[DJ FileSpnR] did a number on this IDJ Live hardware to make room for an integrated iPad. Those that have seen the hardware before may not even recognize it. In stock condition the controller has two turn-table actuators with cross-fader control in between them. The iPad perches on top like a book, making it a fairly bulky setup.

In its hacked format, the device is much more mobile. The physical turntables have been removed, and the center console was moved to one side. This leaves just enough room to fit the iPad 2 (the original iPad is probably too thick for this to work). A cresent of the original turn table bezel has been retained to clamp the iPad in place, and to protect the dock connector at the same time. Now the touchscreen serves as turntable control, with physical sliders to the right which mange the cross-fading.

Check out the video after the break where the DJ explains his alterations and demonstrates the finished project.