Know Audio: Get Into The Groove

November 18, 2021 by Jenny List 62 Comments

The legendary Technics SL1200 direct-drive turntable, as used by countless DJs. Dydric [CC BY-SA 2.5)], via Wikimedia Commons. — The legendary Technics SL1200 direct-drive turntable, as used by countless DJs. Photo by Dydric CC-BY-SA 2.5

For me, the vinyl record player is the spiritual home of my audio listening experience, probably because I’m of the last generation to grow up when vinyl was king. The 12″ album, with its full-size sleeve and copious sleeve notes, used to be an integral part of musical enjoyment that hasn’t been adequately replicated in the age of streaming.

And like anyone who became an adult while CD players were still expensive luxury items, I started my journey into Hi-Fi with a turntable set-up that sounded pretty good. Since a new generation have in recent years rediscovered vinyl, it’s once again something that should be part of any review of audio technology.

I would have started this piece with a full run-down of the constituent parts of a good turntable, but since that’s a piece that I wrote back in 2017, it’s time to investigate some of the audiophile claims about vinyl recordings. It’s fair to say that this is an area where a lot of complete rubbish is spouted by people who should know better, and that’s something I find immensely entertaining to poke fun at. Buckle up. Continue reading “Know Audio: Get Into The Groove” →

Bring That Old Hi-Fi Into The 2020s

October 24, 2021 by Jenny List 41 Comments

It’s a distressing moment for some of us, when a formerly prized piece of electronic equipment reaches a point of obsolescence that we consider jettisoning it. [Jon Robinson] ran into this dilemma by finding the Kenwood Hi-Fi amplifier his 17-year-old self had spent his savings on. It was a very good amp back in the day, but over two decades later, it’s no longer an object of desire in a world of soundbars and streaming music boxes. After a earlier upgrade involving an Arduino to auto-power it he’s now given it an ESP32 and an i2S codec which performs the task of digital audio streaming as well as a better job than the Arduino of controlling the power.

Inside the case is a piece of stripboard with the ESP and codec modules, but there was still the problem of seamlessly integrating it with the amp’s distinctly analogue-era controls. The output from the codec is wired into an audio input – quaintly labelled for a DAT player – and a simple cam on the input selector switch operates a microswitch to select the ESP32.

If you’re dipping your toe in decent audio then an old amp from decades past can make an excellent purchase, but you might wish to educate yourself through our Know Audio series.

Vizio In Hot Water Over Smart TV GPL Violations

October 22, 2021 by Tom Nardi 70 Comments

As most anyone in this community knows, there’s an excellent chance that any consumer product on the market that’s advertised as “smart” these days probably has some form of Linux running under the hood. We’re also keenly aware that getting companies to hold up their end of the bargain when it comes to using Linux and other GPL licensed software in their products, namely releasing their modified source, isn’t always as cut and dried as it should be.

Occasionally these non-compliant companies will get somebody so aggravated that they actually try to do something about it, which is where smart TV manufacturer Vizio currently finds itself. The Software Freedom Conservancy (SFC) recently announced they’re taking the Irvine, California based company to court over their repeated failures to meet the requirements of the GPL while developing their Linux-powered SmartCast TV firmware. In addition to the Linux kernel, the SFC also claims Vizio is using modified versions of various other GPL and LGPL protected works, such as U-Boot, bash, gawk, tar, glibc, and ffmpeg.

According to the SFC press release, the group isn’t looking for any monetary damages. They simply want Vizio to do what’s required of them as per the GPL and release the SmartCast source code, which they hope will allow for the development of an OpenWrt-like replacement firmware for older Vizio smart TVs. This is particularly important as older models will often stop receiving updates, and in many cases, will no longer be able to access all of the services they were advertised as being able to support. Clearly the SFC wants this case to be looked at as part of the larger Right to Repair debate, and given the terrible firmware we’ve seen some of these smart TVs ship with, we’re inclined to agree.

Now of course, we’ve seen cases like this pop up in the past. But what makes this one unique is that the SFC isn’t representing one of the developers who’s software has been found to be part of Vizio’s SmartCast, they’re actually the plaintiff. By taking the position of a consumer who has purchased a Vizio product that included GPL software, the SFC is considered a third-party beneficiary, and they are merely asking the court to be given what’s due to them under the terms of the license.

As firm believers in the open source movement, we have zero tolerance for license violators. Vizio isn’t some wide-eyed teen, randomly copying code they found from GitHub without understanding the implications. This is a multi-billion dollar company that absolutely should know better, and we’ll be happy to see them twist in the wind a bit before they’re ultimately forced to play by the rules.

Drive High-Impedance Headphones With This Stylish USB DAC

October 9, 2021 by Jenny List 3 Comments

For anyone with an interest in building audio projects, it’s likely that an early project will be a headphone amplifier. They’re relatively easy to build from transistors, ICs, or tubes, and it’s possible to build one to a decent quality without being an electronic engineering genius. It’s not often though that we see one as miniaturized as [daumemo]’s USB-C DAC and headphone amplifier combo, that fits within a slightly elongated 3.5 mm jack cover as part of a small USB-to-headphone cable.

The DAC is an off-the-shelf board featuring an ALC4042 IC, it has a line-level output and a handy place to tap off a 5 volt line for the amplifier. This final part is a tiny PCB with two chips, a TPS65135 that produces clean +5 and -5 volt rails, and an INA1620 which is a high-quality audio amplifier set up for 2x gain. All this has been designed onto a very small PCB, which sits inside a 3D-printed housing along with the 3.5 mm earphone socket. The result is a very neat unit far better able do drive high-impedance headphones than the output from an unmodified DAC, but still looking as svelte as any commercial product. We like it.

This may be one of the most compact USB-to-headphone amplifiers we’ve seen, but it’s by no means the first.

Teardown: Sling Adapter

September 29, 2021 by Tom Nardi 27 Comments

The consumer electronics space is always in a state of flux, but perhaps nowhere is this more evident than with entertainment equipment. In the span of just a few decades we went from grainy VHS tapes on 24″ CRTs to 4K Blu-rays on 70″ LED panels, only to end up spending most of our viewing time watching streaming content on our smartphones. There’s no sign of things slowing down, either. In fact they’re arguably speeding up. Sure that 4K TV you bought a couple years back might have HDR, but does it have HDMI 2.1 and Dolby Vision?

So it’s little surprise that eBay is littered with outdated A/V gadgets that can be had for a pennies on the dollar. Take for example the SB700-100 Sling Adapter we’re looking at today. This device retailed for $99 when it was released in 2010, and enabled Dish Network users to stream content saved on their DVR to a smartphone or tablet. Being able to watch full TV shows and movies on a mobile device over the Internet was a neat trick back then, before Netflix had even started rolling out their Android application. But today it’s about as useful as an HD-DVD drive, which is why you can pick one up for as little as $5.

Of course, that’s only a deal if you can actually do something with the device. Contemporary reviews seemed pretty cagey about how the thing actually worked, explaining simply that plugging it into your Dish DVR imbued the set-top box with hitherto unheard of capabilities. They assured the reader that the performance was excellent, and that it would be $99 well spent should they decide to dive headfirst into this brave new world where your favorite TV shows and movies could finally be enjoyed in the bathroom.

Now, more than a decade after its release, we’ll crack open the SB700-100 Sling Adapter and see if we can’t figure out how this unusual piece of tech actually worked. Its days of slinging the latest episode of The Office may be over, but maybe this old dog can still learn a few new tricks.

Continue reading “Teardown: Sling Adapter” →

GLaDOS Voice Assistant Passive-Aggressively Automates Home

September 13, 2021 by Ryan Flowers 7 Comments

With modern voice assistants we can tell a computer to play our favorite music, check the weather, or turn on a light. Like many of us, [nerdaxic] gave in to the convenience and perceived simplicity of various home automation products made by Google and Amazon. Also like many of us, he found it a bit difficult to accept the privacy implications that surround such cloud connected devices. But after selling his Home and Echo, [nerdaxic] missed the ability to control his smart home by voice command. Instead of giving in and buying back into the closed ecosystems he’d left behind, [nerdaxic] decided to open his home to a murderous, passive aggressive, sarcastic, slightly insane AI: GLaDOS, which you can see in action after the break.

Using open source designs from fellow YouTube creator [Mr. Volt], [nerdaxic] 3d printed as much of the GLaDOS animatronic model as he was able to, and implemented much of the same hardware to make it work. [nerdaxic] put more Open Source Software to use and has created a functional but somewhat limited home AI that can manage his home automation, give the weather, and tell jokes among other things. GLaDOS doesn’t fail to deliver some great one liners inspired by the original Portal games while heeding [nerdaxic]’s commands, either.

A ReSpeaker from Seeed Studio cleans up the audio sent to a Raspberry Pi 4, and allows for future expansion that will allow GLaDOS to look in the direction of the person speaking to it. With its IR capable camera, another enhancement will allow GlaDOS to stare at people as they walk around. That’s not creepy at all, right? [nerdaxic] also plans to bring speech-to-text processing in-house instead of the Google Cloud Speech-To-Text API used in its current iteration, and he’s made everything available on GitHub so that you too can have a villainous AI hanging on your every word.

Of course if having GLaDOS looming isn’t enough, you could always build a functional life size Portal turret or listen to the radio on your very own Portal Radio.

Continue reading “GLaDOS Voice Assistant Passive-Aggressively Automates Home” →

Streetfighter 2 placed on table top display with separate arcade control box

Game Like It’s 2021 On A McDonald’s Touchscreen Table

September 8, 2021 by Dave Rowntree 6 Comments

Some of you around the world may have come across these Android-based gaming tables installed in your local fast-food outlet, and may even have been lucky enough to paw at one that was actually working at the time.

Originally based on an ancient mini PC, with a 1080p flat panel LCD and a touch overlay, they would have been mind-blowing for small children back in the day, but nowadays we expect somewhat more. YouTuber [BigRig Creates] got his hands on one, in a less than pleasant condition, but after a lot of soap and water, it was stripped down and the original controller junked in favour of a modern mini PC. To be clear, there isn’t much left beyond the casing and display from the original hardware, but we don’t care, as a lot of attention was paid to the software side of things to get it to triple-booting into Windows 10, Android x86 and Linux running emulation station, covering all those table-gaming urges you may have.

Internally, there is a fair amount of room for improvement on the wiring side of things, and [BigRig] is quick to admit that, but that’s what this learning game is all about. Now, many of you will choke on the very idea of playing games on a table system like this, after all, it’s pretty obvious this will be really hard on the back and neck. But, it does offer the easy option to switch from landscape to portrait orientation, simply by walking around the side, so it does have an upside. Also you’ve got a handy place to dump your beer and the takeaway when it arrives, so maybe not such a bad thing to have in your apartment? And, yes, it does run Doom.

We were particularly amused by the custom boot logo as well as the slick custom art in emulation station. It’s attention to detail like this that makes a build a great one and a conversation piece at parties. Now if only he could sort out that wiring job.

Continue reading “Game Like It’s 2021 On A McDonald’s Touchscreen Table” →