Death To The 3.5mm Audio Jack, Long Live Wireless

October 25, 2016 by Gerrit Coetzee 360 Comments

There’s been a lot of fuss over Apple’s move to ditch the traditional audio jack. As for me, I hope I never have to plug in another headphone cable. This may come off as gleeful dancing on the gravesite of my enemy before the hole has even been dug; it kind of is. The jack has always been a pain point in my devices. Maybe I’ve just been unlucky. Money was tight growing up. I would save up for a nice set of headphones or an mp3 player only to have the jack go out. It was a clear betrayal and ever since I’ve regarded them with suspicion. Is this the best we could do?

I can’t think of a single good reason not to immediately start dumping the headphone jack. Sure it’s one of the few global standards. Sure it’s simple, but I’m willing to take bets that very few people will miss the era of the 3.5mm audio jack once it’s over. It’s a global episode of the sunk cost fallacy.

In the usual way hindsight is 20/20, the 3.5mm audio jack can be looked at as a workaround, a stop over until we didn’t need it. It appears to be an historic kludge of hack upon hack until something better comes along. When was the last time it was common to hook an Ethernet cable into a laptop? Who would do this when we can get all the bandwidth we want reliably over a wireless connection. Plus, it’s not like most Ethernet cables even meet a spec well enough to meet the speeds they promise. How could anyone reasonably expect the infinitely more subjective and variable headphone and amplifier set to do better?

But rather than just idly trash it, I’d like to make a case against it and paint a possible painless and aurally better future.

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A Beautiful Turntable With A Heart Of Concrete

September 30, 2016 by Jenny List 23 Comments

On the face of it, playing a vinyl record is a simple process. You simply mount it on a turntable rotating at the right speed, and insert a needle into the groove. A learning exercise for youngsters used to be a passable attempt at a record player on the kitchen table with a pencil, a large cork, a sharpened matchstick, and a piece of paper. It sounded awful, but it demonstrated well how the audio was recorded.

If you have ever looked into the operation of a more conventional turntable though you’ll know that a little more care and attention is needed. There are many factors which affect the quality of the sound, and you quickly become obsessive about tracking, and sources of the tiniest vibration. Someone who has followed this path is [Mjhara], who has made a very high quality turntable. There is an unusual choice in this project: the tonearm is part of the build rather than fitting a commercial item like most turntable projects.

The platter is machined from a piece of rosewood, weighted and balanced with lead shot, and laminated between two sheets of brass. It sits on a bearing aided by a ring of opposing magnets, and is belt driven by a two-phase induction motor. The base of the turntable is cast as a single piece of concrete, the idea being that the extra weight will aid the damping of vibrations. The tonearm is machined from a piece of wood, and its pivot from brass. The tonearm bearing is a ballpoint pen, a surprising yet inspired choice .

Sometimes audiophiles take their quest for better sound to extremes, and justification for their expenditure can be very subjective. But [Mjhara] assures us that this turntable has an exceptionally good sound, and it is certainly a thing of beauty. Full details are in the Imgur gallery embedded below the break.

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A Real Turn Off

September 27, 2016 by Al Williams 35 Comments

[Newbrain] had a small problem. He’d turn off the TV, but would leave the sound system turned on. Admittedly, not a big problem, but an annoyance, none the less. He realized the TV had a USB port that went off when it did, so he decided to build something that would sense when the USB port died and fake a button press into the amplifier.

He posted a few ideas online and, honestly, the discussion was at least as interesting as the final project. The common thread was to use an optoisolator to sense the 5 V from the USB port. After that, everyone considered a variety of ICs and discretes and even did some Spice modeling.

In the end, though, [Newbrain] took the easy way out. An ATtiny 84 is probably overkill, but it easy enough to press into service. With only three other components, he built the whole thing into a narrow 24-pin socket and taped it to the back of the audio unit’s wired remote control.

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From Audio, To 3D Printed Sculpture, And Back Again

September 23, 2016 by James Hobson 18 Comments

Have you ever wondered what a song looks like? What it feels like in your hands?

Those odd questions have an answer that has taken shape over at [Reify], which has developed a way to turn sound waves into 3D-printed sculptures. These visualizations made manifest can be made from any audio — speeches, the ambience of a forest, classical music, a rocket launch — and rendered in coconut husk, plastic, bronze and more.

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Smart Watch Hack Lets You Use Your 3.5mm Headphones With An IPhone 7

September 23, 2016 by James Hobson 54 Comments

As you may have heard, the iPhone 7 is ditching the 3.5 mm headphone jack in the name of progress and courage. Whatever your take on that, it leaves the end user out in the cold if — for instance — their preferred headphones still use the old format. Here to save you from an untimely upgrade is YouTuber [Kedar Nimbalkar], who has modified a Bluetooth Smartwatch to incorporate a 3.5 mm jack to allow continued use your current headphones.

After opening up the smartwatch [Nimbalkar] removes the speaker, solders in a 3.5 mm headphone jack and clips out an opening in the watch’s case that maintains the watch’s sleek exterior.

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Electrostatic Loudspeakers: High End HiFi You Can Build Yourself

August 3, 2016 by Jenny List 52 Comments

If you have an interest in audio there are plenty of opportunities for home construction of hi-fi equipment. You can make yourself an amplifier which will be as good as any available commercially, and plenty of the sources you might plug into it can also come into being on your bench.

There will always be some pieces of hi-fi equipment which while not impossible to make will be very difficult for you to replicate yourself. Either their complexity will render construction too difficult as might be the case with for example a CD player, or as with a moving-coil loudspeaker the quality you could reasonably achieve would struggle match that of the commercial equivalent. It never ceases to astound us what our community of hackers and makers can achieve, but the resources, economies of scale, and engineering expertise available to a large hi-fi manufacturer load the dice in their favour in those cases.

The subject of this article is a piece of extreme high-end esoteric hi-fi that you can replicate yourself, indeed you start on a level playing field with the manufacturers because the engineering challenges involved are the same for them as they are for you. Electrostatic loudspeakers work by the attraction and repulsion of a thin conductive film in an electric field rather than the magnetic attraction and repulsion you’ll find in a moving-coil loudspeaker, and the resulting very low mass driver should be free of undesirable resonances and capable of a significantly lower distortion and flatter frequency response than its magnetic sibling.
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4-Bit Audio Output Via Voltage Reference

July 30, 2016 by Elliot Williams 18 Comments

[Bruce Land] switched his microprocessor programming class over from Atmel parts to Microchip’s PIC32 series, and that means that he’s got a slightly different set of peripherals to play with. One thing that both chips lack, however is a digital-to-analog converter (DAC). Or do they? (Dun-dun-dun-duuuuhnnnn!)

The PIC part has a programmable, sixteen-level voltage reference. And what is a Vref if not a calibrated DAC? With that in mind, [Bruce] took to documenting its performance and starting to push it far beyond the manufacturer’s intentions. Turns out that the Vref has around 200 kHz of bandwidth. (Who would update a voltage reference 200,000 times per second?)

Anyway, [Bruce] being [Bruce], he noticed that the bits weren’t changing very often in anything more than the least significant bit: audio waveforms, sampled fast enough, are fairly continuous. This suggests using a differential PCM encoding, which knocks the bitrate down by 50% and saves a lot on storage. (Links to all the code for this experiment is inline with his writeup.)

The audio hacks that come out of [Bruce]’s Cornell ECE classes are always a treat. From the lock that you have to sing to open, to chiptunes programmed into an FPGA, there’s something for music fans of all inclinations.