Category Archives: digital audio hacks

The VU Meter and How It Got That Way

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Given its appearance in one form or another in all but the cheapest audio gear produced in the last 70 years or so, you’d be forgiven for thinking that the ubiquitous VU meter is just one of those electronic add-ons that’s more a result of marketing than engineering. After all, the seemingly arbitrary scale and the vague “volume units” label makes it seem like something a manufacturer would slap on a device just to make it look good. And while that no doubt happens, it turns out that the concept of a VU meter and its execution has some serious …read more

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Shell Script Synthesizer Knocks Your SoX Off

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Sound eXchange, or SoX, the “Swiss Army knife of audio manipulation” has been around for as long as the Linux kernel, and in case you’re not familiar with it, is a command line tool to play, record, edit, generate, and process audio files. [porkostomus] was especially interested about the generating part, and wrote a little shell script that utilizes SoX’s built-in synthesizer to compose 8-bit style music.

The script comes with a simple yet straightforward user interface to record the lead and bass parts into a text file, and play them back later on. Notes from C2 to C5 are …read more

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A Stereo Tube Amp For Less Than $5

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Many of us have aspirations of owning a tube amp. Regardless of the debate on whether or not tube audio is nicer to listen to, or even if you can hear the difference at all, they’re gorgeous to look at. However, the price of buying one to find out if it floats your boat is often too high to justify a purchase.

[The Post Apocalyptic Inventor] has built a stereo tube amplifier in the style of the Fallout video games. The idea came when he realised that the TK 125 tape recorder manufactured by Grundig was still using tube audio …read more

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The Hot and Cold of Balanced Audio

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A few summers of my misspent youth found me working at an outdoor concert venue on the local crew. The local crew helps the show’s technicians — don’t call them roadies; they hate that — put up the show. You unpack the trucks, put up the lights, fly the sound system, help run the show, and put it all back in the trucks at the end. It was grueling work, but a lot of fun, and I got to meet people with names like “Mister Dog Vomit.”

One of the things I most remember about the load-in process was running …read more

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Transforming A Bookshelf Speaker Into A Portable Boombox

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There’s a lot of fun to be had in modernizing an old boombox but what about turning one of those ubiquitous shelf speakers into a portable boombox, complete with a handle for carrying? That’s what [GreatScott] did when a friend gave him a just such a shelf speaker.

These days you’d very likely use your phone as the audio source so he included a 20 watt stereo class D amplifier which could be disconnected at the throw of a switch if not needed. To power the amplifier he used 16 18650 lithium-ion batteries which were leftover from previous projects. He …read more

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Freak Out Your Smartphone with Ultrasound

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There’s a school of thought that says complexity has an inversely proportional relation to reliability. In other words, the smarter you try to make something, the more likely it is to end up failing for a dumb reason. As a totally random example: you’re trying to write up a post for a popular hacking blog, all the while yelling repeatedly for your Echo Dot to turn on the fan sitting three feet away from you. It’s plugged into a WeMo Smart Plug, so you can’t even reach over and turn it on manually. You just keep repeating the same thing …read more

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Vintage Headphones Bluetooth Conversion Goes The Extra Mile

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[KaZjjW] wanted to retrofit a pair of nicely styled vintage headphones to be able to play wirelessly over Bluetooth. In principle this is an easy task: simply stick a Bluetooth audio receiver on the line-in, add a battery, and you’re all set. However, [KaZjjW] wanted to keep the aesthetic changes to the headphones at an absolute minimum, retaining the existing casing and volume control, whilst cramming the electronics entirely inside and out of sight.

With the inherent space constraints inside the cups of the headphones, this proved to be quite a challenge. The existing volume potentiometer which hung half outside …read more

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A Fully Open Source Raspberry Pi Synthesizer

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Have you ever seen something and instantly knew it was something you wanted, even though you weren’t aware it existed a few seconds ago? That’s how we felt when we received a tip about Zynthian, a fully open source (hardware and software) synthesizer. You can buy the kit online directly from the developers, or build your own from scratch using their documentation and source code. With a multitude of filters, effects, engines, and essentially unlimited upgrade potential, they’re calling it a “Swiss Army Knife of Synthesis”. We’re inclined to agree.

At the most basic level, the Zynthian is a Raspberry …read more

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Wireless Headphone Hack Dangles Batteries Like Earrings

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Koss Porta Pro headphones are something of a rarity in the world of audio gear: they’re widely regarded as sounding great, but don’t cost an exorbitant amount of money. Since the line was introduced in 1984, they’ve been the go-to headphones for those who don’t subscribe to the idea that you should have to take out a loan from the bank just to enjoy your music.

[Jake Bickhard] is a confirmed Porta Pro disciple, owning enough pairs of them that he’s cagey about confirming how many are actually kicking around his home. The only thing he doesn’t like about them …read more

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Ditch The Tapes, Put An Android In Your Deck

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While we here at Hackaday never question why an individual took on a particular project, it surely doesn’t stop our beloved readers from grabbing their pitchforks and demanding such answers in the comments. Perhaps no posts generate more of this sort of furore than the ones which feature old audio gear infused with modern hardware. In almost every case the answer is the same: the person liked the look and feel of vintage hardware, but didn’t want to be limited to antiquated media.

That sentiment is perhaps perfectly personified by the TapeLess Deck Project, created by [Artur Młynarz]. His creations …read more

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