A Fully Open Source Raspberry Pi Synthesizer

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 Pi 3 with a touch screen, a few rotary encoders, a dedicated sound card, and MIDI support. Software wise the biggest feature is arguably the real-time Linux kernel for the lowest latency possible. There’s also a custom web interface so you can control the Zynthian from another machine on the network if you want. As a matter of course, it also includes a wide array of pre-installed audio packages to experiment and create with.

Kits are offered at various prices from $420 USD for the top of the line model down to unpopulated PCBs for a few bucks. We like that they broke things down this way; allowing users of various skill (and or patience) to pay what they want. If you just want to buy the custom boards and roll your own case and Pi solution, you can do that.

If you want to go all in, you can build one entirely from scratch as well. Everything from the CAD files for the case to their custom rotary encoder library is completely open (most licensed under GPL v3) for anyone to use however they see fit. There’s even a page in the wiki for listing hardware which isn’t officially supported by the project, but remain as options for those looking to cut their own path.

Synthesizers are a fairly popular hacker project, from Google’s AI-powered version to single chip exercises in frugality. If you want to learn even more about the fine line between digital noise and music, check out this fantastic series by our very own [Elliot Williams].

[Thanks to Mynasru for the tip.]

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Wireless Headphone Hack Dangles Batteries Like Earrings

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 is the fact that they’re wired. As it happens, Koss just recently came out with a Bluetooth version of the venerable headphones. But he thought he could do just as well combining a pair of his with a water damaged pair of Bluetooth earbuds he had lying around.

The Porta Pros are easy to take apart, and removing the old wire was no problem. He then cut the “buds” on the Bluetooth earbuds he had, with the intention of just striping the wires and soldering it up to the pads on the Porta speakers. But things didn’t quite go as expected.

What [Jake] hadn’t realized was that the battery for the Bluetooth earbuds wasn’t in the main housing, the power comes from a tiny battery inside each bud. That meant he needed to keep the batteries connected even though the Porta Pro obviously doesn’t have a spot to mount them. In the future he says he’ll address the issue properly, but for now the two batteries hang from the headphones: making it look like he’s wearing the world’s ugliest earrings. But at least he’s happy with the performance of the finished modification, saying they’re even louder now than when they were when wired.

This is a perfect project if you’re cursed with a mobile device that had enough “courage” to take the headphone jack away from you. Though you might first want to study the fine art of soldering headphone wires.

Ditch The Tapes, Put An Android In Your Deck

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 combine vintage cassette decks with an Android phone small enough to fit behind the tape door. An Android application which mimics the look of a playing tape, complete with “hand written” track info, completes the illusion.

The output from the phone is tied into the deck where the audio signal from the tape head would have been, so the volume controls and VU meters still work as expected. Watching the meters bounce around while the animated “tape” plays on the screen really does look incredibly slick, though the effect is somewhat hindered by the fact the physical playback controls don’t seem to be implemented. Incidentally, the whole experience works better if the plastic window on the tape door is removed; that way you can utilize the touch and swipe interface [Artur] has in the software.

We’ve seen previous attempts to modernize the audio cassette experience, but they’ve tended to be more of a novelty than anything. But these decks are nice enough that you can like them non-ironically. Though if we’re talking about portable tape players, there’s only room for one in our cold mechanical hearts.

[Thanks to Nikolai for the tip]

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1960’s Console Stereo gets Raspberry Pi Touch Screen

When he was but a wee hacker, [WhiskeyDrinker] loved to play with the big console stereo his grandparents had. The idea of a functional piece of furniture always appealed to him, and he decided that when he grew up and had a place of his own he’d get a similar stereo. Fast forward to the present, and a Craigslist ad for a working Penncrest stereo seemed to be a dream come true. Until it wasn’t.

The original physical controls are connected to the Pi’s GPIO

As difficult as it might be to believe, sometimes things we read on the Internet are not true. The “working” Penncrest radio turned out to be a dud. But realizing that the look of the cabinet was more important to him than historical accuracy, [WhiskeyDrinker] decided to outfit it with a Raspberry Pi powered touch screen that would look as close to stock hardware as possible.

The final result really does look like some kind of alternate timeline piece of consumer electronics: where chunky physical buttons and touch screens coexisted in perfect harmony. The vintage stereo aficionados will probably cry foul, but let them. [WhiskeyDrinker] did a fantastic job of blending old and new, being respectful to the original hardware and aesthetic where it made sense, and clearing house where only nostalgia had lease.

A HiFiBerry DAC+ Pro is used to get some decent audio out of the Raspberry Pi, and the touch screen interface is provided by Volumio. [WhiskeyDrinker] mentions that it even has a GPIO plugin which he successfully used to handle getting the physical buttons to play nice with their digital counterparts.

Updating old audio gear is always a sensitive subject around these parts. Sometimes they go so far that the original hardware is almost an afterthought. On the other side of the spectrum are the projects which try to take modern gear and mimic the look of the classics. In any event, one thing is clear: they don’t make ’em like they used to.

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Stomping On Microcontrollers: Arduino Mega Guitar Effects Pedal

Effects pedals: for some an object of overwhelming addiction, but for many, an opportunity to hack. Anyone who plays guitar (or buys presents for someone who does) knows of the infinite choice of pedals available. There are so many pedals because nailing the tone you hear in your head is an addictive quest, an itch that must be scratched. Rising to meet this challenge are a generation of programmable pedals that can tweak effects in clever ways.

With this in mind, [ElectroSmash] are back at it with another open source offering: the pedalSHIELD MEGA. Aimed at musicians and hackers who want to learn more about audio, DSP and programming, this is an open-hardware/open-software shield for the Arduino MEGA which transforms it into an effects pedal.

The hardware consists of an analog input stage which amplifies and filters the incoming signal before passing it to the Arduino, as well as an output stage which does the DAC-ing from the Arduino’s PWM outputs, and some more filtering/amplifying. Two 8-bit PWM outputs are used simultaneously to make pseudo 16-bit resolution — a technique you can read more about in their handy forum guide.

The list of effects currently implemented covers all the basics you’d expect, and provides a good starting point for writing custom effects. Perhaps a library for some of the commonly used config/operations would be useful? Naturally, there are some computational constraints when using an Arduino for DSP, though it’s up to you whether this is a frustrating fact, or an opportunity to write some nicely optimised code.

[ElectroSmash] don’t just do pedals either: here’s their open source guitar amp.

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1920’s Claratone Radio Runs Windows 10

In the past we’ve mentioned how there are different schools of thought in terms of how to bring a vintage piece of hardware into the 21st century. You can go down the preservationist’s route, carefully grafting the original components with more modern ones, or you can take the nuclear option and blow all that dusty old gear out of the water. [Derek Traxler] clearly decided to go with the latter option on his recent conversion of 1920’s era Claratone tube radio to an Internet radio and podcast player. Not only is there little left of the original device beyond its knobs and wooden case, but he’s even managed to cram a Windows 10 computer into the base for good measure.

The core of the radio is a LattePanda, an extremely powerful Intel single board computer. It’s running Windows, and loads up a list of Internet radio streams and podcasts to play from a USB thumb drive that’s built into an old vacuum tube. The LattePanda uses its built-in Arduino to interface with the radio’s original front panel knobs, which now are used to switch between streams. A particularly neat effect is the static and cross-talk that’s artificially added when switching “stations”, making it sound like you’re really dialing in a station rather than just selecting between digital files.

On the audio side, the LattePanda is connected to a SX400 amplifier, which in turn drives the external speakers. While [Derek] mentions it isn’t quite perfected, a MSGEQ7 graphic equalizer chip is used to control LEDs mounted inside the original radio’s vacuum tubes. In the video after the break, you can see the tubes flashing madly along with the music, giving an interactive effect to the final product. Unfortunately it seems you can only see the tubes when the radio has its “hood” up, though.

If this egregious lack of historical preservation has brought a tear to your eye, never fear. We’ve covered some proper restoration work on vintage audio gear which may level you out.

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Recreating the Radio from Portal

If you’ve played Valve’s masterpiece Portal, there’s probably plenty of details that stick in your mind even a decade after its release. The song at the end, GLaDOS, “The cake is a lie”, and so on. Part of the reason people are still talking about Portal after all these years is because of the imaginative world building that went into it. One of these little nuggets of creativity has stuck with [Alexander Isakov] long enough that it became his personal mission to bring it into the real world. No, it wasn’t the iconic “portal gun” or even one of the oft-quoted robotic turrets. It’s that little clock that plays a jingle when you first start the game.

Alright, so perhaps it isn’t the part of the game that we would be obsessed with turning into a real-life object. But for whatever reason, [Alexander] simply had to have that radio. Of course, being the 21st century and all his version isn’t actually a radio, it’s a Bluetooth speaker. Though he did go through the trouble of adding a fake display showing the same frequency as the one in-game was tuned to.

The model he created of the Portal radio in Fusion 360 is very well done, and available on MyMiniFactory for anyone who might wish to create their own Aperture Science-themed home decor. Though fair warning, due to its size it does consume around 1 kg of plastic for all of the printed parts.

For the internal Bluetooth speaker, [Alexander] used a model which he got for free after eating three packages of potato chips. That sounds about the best possible way to source your components, and if anyone knows other ways we can eat snack food and have electronics sent to our door, please let us know. Even if you don’t have the same eat-for-gear promotion running in your neck of the woods, it looks like adapting the model to a different speaker shouldn’t be too difficult. There’s certainly enough space inside, at least.

Over the years we’ve seen some very impressive Portal builds, going all the way back to the infamous levitating portal gun [Caleb Kraft] built in 2012. Yes, we’ve even seen somebody do the radio before. At this point it’s probably safe to say that Valve can add “Create cultural touchstone” to their one-sheet.

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