What is a DAC?
Want better sound quality and more volume from your laptop/iPhone/MP3 player? Here's a refresher course in how you can achieve this with the simple addition of a USB DAC (or digital to analogue converter) to your set up.
There's an intimidating range of audio products available to us and whether its headphones, smartphones, speakers or even streaming services, they’re all promising you incredible sound. But there’s an undisputed way you can make your existing setup simply - better. By adding a DAC.
For those of you new to this concept, you’ll want to understand exactly what’s behind this sharp sounding acronym before you take our word for it.
So what is a DAC?
Much like headphone amplifiers, standalone DACs came about as a response to poor audio quality at the consumer level. Back in the day, it was a lot tougher to find good hardware, and nerds like me had to deal with devices that couldn’t keep up with higher-end headphones and speakers. Sometimes the DAC assembly would be improperly shielded - introducing staticy noise - or it’d be a little too cheap, making the output kinda crappy. Lower sample rates, badly encoded MP3s… there were tons of things that children of the 80s and 90s had to deal with when it came to audio. Who wants to listen to low-quality tunes?
But digital music has come a long way since then. Better tech has made shortcomings of even the cheapest chips almost nonexistent, while digital music has exploded in quality past the point of diminishing returns. Where it used to be true that your Walkman’s or laptop’s internal DAC chip wouldn’t be suitable for high-bitrate listening, there are plenty of more compact units nowadays that can keep up.
You can buy a DAC and amp separately, or buy a combo unit that contains both. It’ll improve your sound in a couple ways:
A DAC eliminates interference that your onboard sound card may experience inside your computer and ensures you’re getting the best possible sound quality. (My headphones get a pretty noticeable buzzing noise when plugged into the computer, for example - a DAC eliminates this.)
An amplifier boosts the volume of the sound, which is particularly useful for higher impedance headphones (headphones above 32Ω) that will sound quiet through a regular headphone jack.
Amplifiers will often come with other features, like bass boost or other equalizer functions, that allow you to alter the sound.
Note that you can only get the full benefit of a DAC/amp combo with your desktop or laptop computer, via USB or SPDIF. While you can get DAC/amp combos for iPods and other mobile devices, the DAC half of the device won’t actually work. Only the amp half will. This is still great for giving your sound a boost in volume if it’s coming out too quiet, but just know that the DAC won’t work—so if you only plan on using it with an iPod, you don’t need a DAC or combo, just a mobile amp.
A DAC, or digital to analogue converter, is the device that translates digitally stored information from a laptop, iPod or other such device into the analogue sound that we can hear.
Types of Digital to Analog Converters
There are many different kinds of digital to analog converters. At Future Electronics we stock many of the most common types categorized by resolution, interface, supply voltage, number of channels, packaging type and power consumption. The parametric filters on our website can help refine your search results depending on the required specifications.
The most common number for channels is 1 channel and 2 channels. We also carry digital to analog converters with up to 12 channels. Supply voltage can have a range from 0 V to 32 V, with the most common voltage being between 2.7 V and 5.5V.
Why does a signal need to be converted at all?
ll audio, whether it’s stored on vinyl or in an MP3 is a compression wave when it’s played back. When computers record an analog signal, typically it will be displayed in what’s called a waveform, or a representation of the wave where the Y axis is amplitude (how powerful the wave is), and the X axis is time. Each wave will have a crest and valley - called a period - and how many periods there are in a second is called frequency (displayed as Hz). If you’ve heard that word before, you know that what frequency a sound is also corresponds to what note it is. The higher the frequency, the higher the note.
The job of the DAC is to take a digitally stored recording and turn it back into an analog signal. To do that, it needs to translate the bits of data from digital files into an analog electrical signal at thousands of set times per second, otherwise known as samples. The unit then outputs a wave that intersects all those points. Now, because DACs aren’t perfect, sometimes this leads to problems. These problems are jitter, narrow dynamic range, and limited bitrate.
Before launching into the nuts and bolts of how everything works, you need to know three terms: bitrate, bit depth, and sample rate. Bitrate simply refers to how much data is expressed per second. Sample rate refers to how many samples of data are taken in a second, and bit depth refers to how much data is recorded per sample.
The original analogue sound made by our favourite bands and artists are recreated in a digital format for our storing convenience – i.e. MP3, FLAC or Apple Lossless. While computers can understand these digital signals, we as humans (assuming our readership is of this world) cannot, nor can your speakers or headphones. So before we can listen to it, the digital signal needs to be returned once more to analogue. This is the function kindly undertaken by the DAC which will be built into your laptop or music player. The better the DAC, the higher quality the conversion and therefore the better sound you’ll hear from your speakers/headphones.
You may not have realised it, but you’ve used a DAC every time you have played music through your laptop or smartphone. These products have their own built-in but usually very poor quality DAC because it’s been designed to do one small part of a devices total functions on a budget. So if you’ve been investing in some nice speakers or headphones, you’re not going to be making the most of them unless you use a separate DAC which has been designed and optimised entirely for making hi-fi sound quality.
How does a DAC fit into my current setup?
DACs are available in all sorts of sizes and price points, so if it’s going to be staying put you can invest in a more premium, larger unit which might fit into your Hi-Fi stack, or a mid size one to sit alongside your PC/Laptop.
But if you’re looking for something small and portable you need look no further than a USB headphone DAC like our DacMagic XS. Not only is it an excellent little DAC to perform a higher quality conversion on your audio, it’s also got a headphone amp built in. This amp is 10 x more powerful than the headphone output on your laptop. It hooks straight up to your laptop via USB and has a headphone jack so you can plug your headphones straight in and bypass that inferior built in DAC in the laptop for superior sound on the go. Thanks to the extra power from the amp, you’ll get a load more volume, detail and bass for your buck, finally making the most of your headphones.
What is bit depth and dynamic range?
If you’ve listened to really old MP3 files or crappy MIDI music from your old consoles, you’ll probably notice that they can’t really ramp up volume in a given music track all that well, or that competing instruments are really really difficult to pick out if they’re all going at once. This is what bad dynamic range sounds like. Dynamic range in this instance simply refers to the difference between all possible volumes of sounds in a given file.
What governs the theoretical limits of the dynamic range of an audio file is the bit depth. Basically, every single sample (discussed above) contains information, and the more information each sample holds, the more potential output values it has. In layman’s terms, the greater the bit depth, the wider the range of possible loudness of notes there are. A low bit depth either at the recording stage, or in the file itself will necessarily result in low dynamic range, making many sounds incorrectly emphasized (or muted altogether). Because there’s only so many possible loudness values that a sound could have inside a digital file, the lower the bit depth, the crappier the file should sound however you listen to it.
he most common bit depth is 16, meaning: for every sample, there’s a possible 16 bits of information, or 65,536 integer values. In terms of audio, that’s a dynamic range of 96.33dB. In theory, that means that no sound under 96ish dB should be deleted or incorrectly assigned a loudness value.
While that may not sound terribly impressive, you really need to think hard about how you listen to music. If you’re like me: that comes from headphones 99+% of the time, and you’re going to be listening to your music at a volume much lower than that. For example, I try to limit my sessions to about 75dB so I don’t cook my ears prematurely. At that level, added dynamic range isn’t going to be perceptible, and anyone telling you otherwise is simply wrong. Additionally, your hearing isn’t equally-sensitive across all frequencies either, so your ears are the bottleneck here.
While bit depth is important, what most people are familiar with in terms of bad-sounding audio is limited bitrate. Ever listen to music on YouTube, then immediately notice the difference when switching to an iTunes track or high-quality streaming service? You’re hearing a difference in bitrate.
If you’ve made it this far, you’re probably aware that the greater the bit depth is, the more information the DAC has to convert and output at once. This is why bitrate - the speed at which your music data is decoded - is important. If the bitrate is low, not enough data will be converted to create the analog wave, meaning less information is converted, meaning you hear crappier audio. It’s really as simple as that.
So how much is enough? I usually tell people the 320kbps rate is perfectly fine for most applications (assuming you’re listening to 16-bit files). Hell, it’s what Amazon uses for its store, and truth be told most people can’t tell the difference. Some of you out there like FLAC files—and that’s fine for archival purposes - but for mobile listening? Just use a 320kbps MP3 or Ogg Vorbis file. The amount of space “lossless” files like FLAC takes up is enormous, and for little to no perceptible benefit when you’re on the go.
If you’ve got space to spare, maybe you don’t care as much how big our files are - but smartphones generally don’t all come with 256GB standard… as of now. But if you can’t tell the difference between a 320kbps MP3 and a 1000+kbps FLAC, why would you burn 50MB of space when you could get away with say 10?
No comments:
Post a Comment