The Ins and Outs of DACs by AudioQuest

On April 28th 2016

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We had AudioQuest write a guide about DACs to celebrate the release of their new Dragonfly series. Here's everything you wanted to know about DACs but were afraid to ask. 

What is a Digital-to-Analog Converter?

The Mystery and Ubiquity of Digital-to-Analog Conversion

While it might seem as though digital-to-analog converters (commonly referred to as “DACs”) are as new and mysterious as the proven existence of gravitational waves, they have actually been around for quite a while. In fact, many of us use them on a daily basis without even realizing it. DACs are commonly found in laptops and tablets, mobile phones, televisions, gaming consoles, CD or Blu-ray players, and practically every other form of digital device that can be used to send an audio signal or play music.

Simply put, a DAC, as its name suggests, converts digital audio information (comprised of 1s and 0s) into an analog signal that can be sent to headphones, loudspeakers, amplifiers, and/or receivers, to be heard and enjoyed by the listener.

That’s right: Anytime you’re listening to music, watching a movie, or even playing a YouTube video, the digital audio data is first sent through a DAC that converts the 1s and 0s to the analog waveforms that our headphones, speakers, and home stereos deliver to our ears as music.

Ones and zeros, you ask?

Yep.

The Sounds We Hear in Nature

Traditional passive loudspeakers and amplification devices—receivers, power amps, integrated amps—do not send digital signals. Similarly, our ears do nothearin digital. The sounds we hear in nature—birds in the trees, traffic in the street, the constant innocuous whirring of air-conditioning units, musical instruments, the voices of those around us—are transmitted in soundwaves that travel through the air and to our ears as varying voltages that create an analog signal.

Vinyl Me, Please members will certainly sympathize with the many music enthusiasts who prefer analog recordings for their inherent “warmth” or “tactility.” Some ascribe this preference to the “morenatural” sound of analog recordings—something that, for many of us, is difficult to describe, but nevertheless as obvious and true as day and night.

Still, musicians, engineers, and music lovers forged a path into today’s digital world for plenty of good reasons: convenience and portability being chief among them, as well as the promises of durability and “perfect sound forever.” That is, sound free from the clicks, pops, pitch shifts, and other audible characteristics—alternatingly endearing and annoying—that had become inherent to dusty vinyl and well-loved cassettes.

Enter the Compact Disc.

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Lasers and Lenses and Stuff

Anything butnatural, with the emergence of the Compact Disc, music lovers not only gained plastic packaging that was nearly impossible to crack open, but were also introduced (albeit stealthily) to an entirely new way of listening to and consuming music. Rather than convertingmagneticsignals intoelectricalsignals that would then be amplified and delivered by loudspeakers, we were now playing with lasers and lenses and stuff.

Totally ’80s, right? Whoever came up with this stuff must’ve been areal genius.

Nerd alert:We will now briefly discuss the mechanics of a Compact Disc (don’t quote us on any of this…)

Data is stored within Compact Discs along a long spiral comprising flat areas and bumps. Within the CD player, a drive motor spins the disc, while a laser/lens assembly emits a laser onto the spinning disc and determines whether it’s traversing a flat area or a bump. Finally, a tracking mechanism moves the laser/lens assembly from the inside of the disc toward the outside, all while following that long spiral of data.

Those flat areas and bumps are our aforementioned 1s and 0s—1s indicative of some bit of important information, 0s indicative of, duh, nothing—and together they form a binary series that determines the digital signal.

However, as we mentioned earlier, we humans don’t hear in digital. The digital signal that is embedded within the CD, and which has been read by the CD player’s laser/lens assembly, must be converted into an analog waveform that we can hear and enjoy.

Enter the digital-to-analog converter. (Yasssssss!)

All Hail the Mighty DAC

In the very simplest sense, a DAC processes those zeroes and ones, determines the frequency with which they occur, and ascribes to them the varying voltages at regular intervals necessary to produce an analog signal.

Remember: There is no “on” or “off” in the natural world. In an analog signal, the voltage of the signal varies continuously with the pressure of the sound waves. In a digital signal, however, the data is represented by a binary series of finite values—1s and 0s, on or off.

Within a digital signal, the length of the binary number is referred to asbit depth, while the timing of the intervals is thesampling rate, asamplesimply being a value at a particular point in time or space. When recording a standard (or “Red Book”) Compact Disc—the kind we all know and love (or love to hate)—a sample is taken 44,100 times per second, measured to an accuracy of 16 bits. Thus, CDs operate at audio resolutions of 16-bit/44.1kHz.

Higher resolutions are possible and are becoming more widely available, but, in practice, these remain relatively rare. Of course, lower resolutions—such as those employed by MP3s and many streaming services—are far more prevalent.

There are more variables involved than you probably want or need to know about. In short, digital audio data can be stored in a wide variety of sample rates, bit depths, and formats. The DAC is responsible for deciphering all of that digital data and communicating it as precisely as possible—that is, as close as possible to the original analog waveform—so that we can enjoy it asmusic.

All hail the mighty DAC.

But, wait: Not all DACs are created equal.

Designed to Make Music

As we mentioned earlier, DACs are everywhere: in our laptops and tablets, smartphones, televisions, gaming consoles, CD or Blu-ray players, and on and on.

Unfortunately, however, not all of these devices love music as much as we do. That is to say, they may not have been designed with music as their first priority.

For instance, the sound card that’s built into your computer and feeds its headphone jack is an example of a DAC. However, computers and most other digital devices are not optimized for sound. They have other priorities to meet and functions to fulfill—browsing the Internet, taking and editing photographs, sending and receiving emails and texts, juggling our various precious apps, and so much more.

For most digital devices, delivering audio is just one of numerous functionalities, all of which are compromised to some extent.

Inferior DACs will make sound, but they may not makemusic. They fail to fully communicate theessenceof music—its beauty, grace, exquisite sorrow, sweeping joy, blinding madness, or restorative power.

Lesser DACs might not support all data rates and files types. Worse, due to their poorly designed clocking circuitry (the parts that keep track of the intervals between samples), they can even introduce digital timing errors known asjitter.

The most important thing to know about digital audio jitter is that it’sbad—very bad. The more jitter present within an audio signal, the worse the sound will be. Imagine: If the DAC is getting the timing wrong (which is to say, outputting samples at the wrong moments in time), then the resulting analog waveform will be different from the original. We hear this as a loss of focus in the stereo image: Instead of emerging from a large, deep space between two speakers, the music shrinks and collapses upon itself. Instead of being imbued with natural tone color and impressive dynamics, the music is flat, lifeless, shrill, and fatiguing.

Better DACs are capable of reducing jitter, enabling cleaner, clearer, more naturally beautiful sound—sound that is detailed, but never harsh; warm, but never saccharine; full-bodied, but never bloated. You get the idea: sound that more closely resembles that of the natural world.

Far superior sound—and, thus, much more beautiful, engaging music—can be enjoyed when using an external, purpose-built DAC. These DACs are built around high-precision parts and sophisticated microprocessors that have been carefully designed to minimize noise and accurately determine the timing of samples. Unlike the soundcard built into your laptop, these DACs are designed to makemusic.

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DACs on DACs on DACs

We live in a world of apparently infinite riches, in which entertainment is always at our fingertips, music is more abundant and accessible than ever before, and DACs come in all shapes and sizes.

The DAC that’s right for you will, of course, depend on your needs and lifestyle.

What functionalities are you interested in? What types of inputs will you use? Will your DAC serve as a constant travel companion or will it be used only at home? Do you listen primarily through headphones? If so, you’ll want a DAC that also serves as a headphone amp. Those exist, too!

So, how do you choose? Consider the information we’ve shared here, answer the questions above, consult the experts—some of our favorites are the good people at AudioStream.com, DigitalAudioReview.net, and, of course, our friends at AudioQuest—and, whenever possible,listen.

The DAC that’s right for you will invariably be the one that brings you the most listening pleasure and satisfaction, inspiring you to find and enjoy more and more beautiful music.

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