What Is a DAC?

Digital to analog converter (DAC) devices are a common part of our day-to-day lives.

Whether listening to your favorite podcast on the way to work or blasting some tunes while cleaning the house, you are most likely using one - unless you’re a vinyl connoisseur or Walkman aficionado.  

So, what is a DAC?

Well, continue reading to find out.

What Is a DAC? 

It converts digital information to a continuous analog signal. That signal is then amplified and is playable through speakers or headphones. Without this conversion, you won’t be able to hear anything played from a digital source. 

Most tech devices have it, including: 

• Smartphones
  
• Tablets
  
• Computers
  
• Laptops
  
• TVs

Ok, but why does my music need to be converted?

Most tech is digital nowadays, and the same goes for music. All audio files stored on our devices basically carry our music as bits of data expressed as a series of zeros and ones - think, The Matrix. 

Unlike computers, humans can’t decipher this information. The purpose of the DAC is to convert the nonsensical numbers into a continuous analog sound signal. 

And while the majority of our digital devices have built-in DACs, their quality is often lackluster. Therefore, people looking for a better and truer sound representation opt for an external digital to analog converter.

DAC Benefits

A dedicated external DAC can help if you have audio issues like:

Noise-floor problems

If you can hear a hiss during the quiet sections of your music, or an audible noise throughout the playback, then a DAC will help.

These problems may originate from computer fans, spinning hard drives, etc. A common reason is the poor placement of the soundcard in relation to other device internals. If it isn’t well insulated, there will be noise. 

An external digital to analog converter will bypass your device's internal one, thereby omitting any sounds caused by components. Furthermore, a good unit will undoubtedly have much better filters.

Jitter

Jitter is a timing inconsistency between the source and the DAC. It results in momentary changes in pitch and only occurs at very high frequencies that are usually beyond our hearing capabilities.

Although this is a rare problem, there are a few ways a good DAC will fix it:

• Dedicated clock generator for syncing
• Higher sample rate conversion - reduces the chances for errors with less space between data points.
• Separate jitter reduction filter 

Aliasing

This happens when different signals become indistinguishable from one another during low-rate sampling. This will result in added distortion since the reconstructed signal differs from the original analog signal.

To avoid this, premium DACs incorporate better and more precise filtering technology. 

Limited bitrate

If the decoding speed of the system is low, you won’t be able to extract all the information present in each sample - resulting in lower overall audio quality.  

A high-end DAC has higher decoding speeds, and therefore, it has a greater capacity to convert audio at higher bit rates. This means getting the most out of the recording’s dynamic range with a better signal-to-noise ratio. 

Aside from fixing these potential issues, a good DAC may significantly improve your setup.

However, it’s important to remember that sound systems are chains. Whether just a computer and headphone set-up or a full-blown home theater system - each component contributes toward the end result.

Here are a few things you may want to consider before deciding on a new DAC.

Audio file quality

For example, if your digital music collection consists of lossy MP3s, you should not expect any substantial upgrade to your sound. For high-quality audio, use CDs, lossless audio formats (FLAC, WMA, Apple Lossless), or subscription services like Tidal or Apple music.

Good DAC units are only as good as the signals they receive.

Headphone and speaker quality

Ultimately, the amount of detail you hear from your music depends on your headphones or speakers.

A digital to analog converter doesn’t affect the output’s frequency response. 

Drivers’ quality will also greatly vary the sound. If you use the same system with two different speakers or headphones, be certain that they will sound different. 

Keep in mind that acoustics come into play with any speaker setup. 

You need to consider all factors, including speaker positioning, environment, size of space, etc. 

Let’s now look closer at how digital to analog converters work.

How Does a DAC Work?

To fully understand how it works, let's first discuss the difference between the two kinds of signals.

Analog signal

All sounds we hear naturally – traffic, singing birds, neighborhood kids playing – are soundwaves that travel through the air. These waves are continuously varying analog signals that our ears pick up and hear.

The same happens in a recording studio where microphones capture the soundwave, turn it into an electrical current, and copy it onto a medium. When it is vinyl or magnetic tape, then the audio remains in analog form. If that’s the case, a DAC unit has no purpose.

For example, when you look closely at the surface of a vinyl record, the grooves you see are the actual representation of soundwaves pressed onto it. 

Digital signal

Compared to analog, digital signals are much different. 

The former is a constantly variable form of information, while the latter is incremental data.

Most modern recording studios use digital equipment - primarily computers with digital audio workstations (DAWs). 

With digital, the signal primarily records in analog, but before being written, it converts them using an analog to digital converter (ADC). 

To play it back, we need a DAC audio device.

The data stored in these files is:

• Samples – measurements, known as snapshots of the input signal’s amplitude at regular intervals
  
• Sampling rate - the timing of each measurement interval
• Bit Depth - is the measured value of the amplitude - represented in binary and digital length. 

This digital data must then convert to audible analog sound waves. DAC converts the samples back to voltage levels for output with filtering to enhance the audio quality.

This is why DACs are such a necessity. Without this tech, our digital devices would be unable to reproduce the recorded analog sounds. 

And while there are no perfect conversions. More or less, it achieves close approximations of the original signal. 

Now that we have explained some general terms about analog and digital audio - let’s dig deeper into what makes a DAC tick.

DAC Architecture

A DAC is basically a converter chip in an electronic circuit. That chip, however, is certainly not the only thing that defines the quality of reproduction. Much like your sound system, all the components in a DAC device play an integral part and determine the outcome. 

There are several kinds of DACs based on architecture. Let's look at the two most common ones.

Resistor-to-Resistor (R2R) Ladder DACs

The Resistor-to-Resistor (R2R) system is the simplest method of achieving digital to analog conversion. It does this by arranging many resistors in the shape of a ladder, but only two get exploited.

Each bit of information contributes a small burst of voltage to the network of resistors. This, in turn, creates a new continuous (analog) voltage which is an approximate copy of the original signal caught at both ends of the ladder.  

Due to the lack of signal processing, this simple method is fast, accurate, and usually much cheaper.  

Delta-Sigma DACs

This design encodes high-resolution digital signals into a lower-resolution but higher sample-frequency signal. It is then mapped to voltages and smoothed with an analog filter.
Due to the more intensive processing, delta-sigma DACs require powerful computing chips.

The accuracy of Delta-sigma depends on the dynamic range. It works best at higher signal levels but can lose resolution at the lower ones. 

Most modern DAC units implement a combination of delta-sigma and noise shaping filters.

Speaking of filters, let's now discuss how they contribute to the DAC system.

Filteringw

Filters are a crucial component in a DAC device because they remove noise and unwanted signal parts. These can be either digital or analog. 

Depending on their location within the chain, they can be before or after decoding. Based on the implementation, digital filters are usually in a chip, while analog filters consist of components such as capacitors and resistors.

The primary type of filter is the reconstruction (sometimes anti-aliasing or both) filter. It is a low-pass filter that helps sequence samples to achieve a smooth analog signal.

Other types of filters are:

• Digital filters are powered by algorithms to fill gaps by predicting the likely behavior of the signal. 
• Noise Shaping is a filter designed to push noise into less perceivable frequencies to improve lower frequency sounds.

DAC manufacturers apply digital filtering algorithms and analog components differently. As a result, you can expect sound variations. 

A DAC unit may also have the ability of upsampling or oversampling. This type of digital signal processing aims to increase the sample rate of the original signal, therefore improving it. 

Different Types of Digital-To-Analog Converters

There are various DACs available to suit everyone’s needs and budget.

Let’s have a look at the main types:

Desktop and laptop computers (USB DACs)

USB DACs are often the best option for computers and laptops. You can power these devices via the USB port.

They usually have extra digital or analog inputs and outputs. This way, you’ll be able to connect multiple devices. 

Some USB DACs also have built-in headphone amps (DAC/AMP), which is always great when looking to maximize the use of your high-end headphones. If underpowered, you are only scratching the surface of their capabilities. 

An external DAC can also be an excellent upgrade for gaming, reducing unwanted noise and improving the immersive experience. For example, it will bring quieter sounds forward and make it easier to hear your enemy’s footsteps.  

Smartphones and tablets (Portable USB DACs)

These small digital to analog converters can connect to your phone, tablet, or laptop. They are usually the size of a USB stick or an Apple dongle. 

They almost always come with a headphone amplifier.

Even though another device to carry around seems frustrating, they are a good idea if you want to use high-end cans with a phone that lacks a 3.5mm mini-jack.

Home Stereo Systems (Component DACs)

Depending on your setup, these DACs can get large and expensive. The usual reasons include:

• A wider range of supported formats
  
• Support for larger sample rates and higher bit depths
  
• Variety of connections
  
• Bonus features like selectable filters and other means of tweaking the output

Whether for a home theater system or a Hi-Fi music setup, you can mix and match the various components and find the optimal configuration.  

Another option is a standalone wireless DAC. This way, you can enjoy high-fidelity audio via Bluetooth, Wi-Fi, or Airplay from any connected device.

Other DAC Applications

In addition to its prevalence in the audio world, other common applications are:

Telecommunications

A microphone picks up your voice and converts it into a digital signal when talking on a telephone. That signal then travels to the other end of the line, and a DAC turns it back into analog so that the recipient will hear you.  

A modem is an ADC/DAC device often found in phones, routers, radios, etc. 

Video

Nowadays, most TVs and Displays use HDMI, a completely digital connection that negates digital to analog conversion requirements. However, older TVs had analog RCA inputs. These were only able to receive video signals from devices with built-in DACs, like DVD players. 

Moreover, you can find DACs used in:

• Data Acquisition Systems
  
• Calibration
  
• Motor Control
  
• Digital Potentiometers

Wrap Up

It is a necessary piece of tech in our modern lives that lets us enjoy the many benefits.

Whether you need a DAC for better audio depends on your situation. Maybe you experience issues during playback? Or perhaps you want to use high-end headphones to their fullest potential?

Well, a DAC may just be what you’re looking for.

Be sure you consider your whole setup before finalizing any decision, as a DAC system is not a fix-all solution.