How DAC Works
Whether you’re listening to a CD player, mechless head unit, smartphone, or some other digital tech, your car’s audio experience hinges on a component you may have never even heard of. The digital to analog converter (DAC) is responsible for taking digital information stored on CDs and streaming music files and converting it into something that can be played over your car speakers. The one exception to this rule is conventional AM/FM radio, which starts off with an analog signal. Every other audio source in your car is stored in some type of digital format—whether that be a physical CD, streaming music, or bits and bytes on a hard drive. In order to translate that digital information into an analog signal that’s capable of driving your speakers, and thus create music you can actually listen to, it has to pass through a digital to analog converter.
From Analog to Digital and Back Again
Music, and other forms of audio recordings, start out as analog signals, and at one time they were also recorded in analog formats. Records and audio cassettes are both examples of analog media formats, but the modern audio recording has since moved into the digital realm, first with CDs and later with digital files like MP3s and streaming services like Spotify and Apple Music. The purpose of storing and transmitting music and other audio recordings in digital formats is primarily an issue of storage space and convenience. A compact disc can store more audio data than a record or compact cassette in less space. Digital storage media like a hard drive or flash drive can store a greater amount of audio data in the form of MP3s and other files. After an analog audio recording has been converted into digital data, it’s of little use until it’s converted back. While in a digital format, the signal is abstracted as binary data that can’t drive a speaker or create an audible sound on its own. In order to do so, it has to be passed through a digital to analog converter.
Digital to Analog Conversion
Virtually every audio device that relies on digital media contains a digital to analog converter. That includes everything from your iPhone or iPod to the head unit in your car. In home theater contexts, you can find standalone DACs that are designed for use with specific music playing devices that either don’t include a DAC or have a digital output. These standalone units are typically higher in quality than most built-in DACs, so they are capable of more faithful reproductions of the original analog signals. Although there are different types of DACs, they all perform the same basic function: converting abstracted digital data into a physical signal that can then be amplified and used to drive loudspeakers. This is usually accomplished by converting the digital information into a corresponding set of stepped pulses, which is then smoothed out via interpolation. The quality of the resulting signal is dependent on how the DAC works, so the same digital information can provide a different quality and flavor of sound depending on the DAC that it’s passed through. Most digital to analog converters are contained on integrated circuits due to size and cost constraints, but there are also DACs that use vacuum tubes to produce a warmer, more detailed sound.
Portable Car Audio DACs and Head Units
Most portable DACs are designed for use with laptops, and they essentially offload the heavy lifting of converting digital music to an analog signal from computer software to a physical device. This type of portable DAC can be used in your car as well, if you have an audio source that is capable of outputting via USB and your head unit has an analog input. The other way that DACs come into play in cars is that some head units include digital inputs, typically in the form of a USB or proprietary jack. The way that this type of connection works is that it allows you to plug in your iPhone, tablet, or any other MP3 player and offload the processing to the head unit, rather than relying on the DAC in your phone or another device.
Do You Need a DAC Component in Your Car?
If you want the best possible sound quality, and you’ve already upgraded your head unit, amplifier, or speakers, then adding a DAC can help push your sound quality to the next level. Even if you have a factory car stereo that sounds decent, you can benefit from adding a portable DAC like the Apogee One, which sits between your phone or portable music player and your car stereo. It’s also important to remember that you don’t have to buy an expensive portable DAC to experience better sound. Your car stereo probably has a decent DAC built right in that’s designed for use with car speakers. Instead of using an analog connection like an auxiliary jack to plug your phone or music player into your car stereo, consider using a USB port. If your car stereo has a USB port, or you’re willing to upgrade, you can feed digital music files directly to the stereo. This allows the built-in DAC in the head unit to do the heavy lifting instead of the DAC in your phone or music player, which will typically result in better-sounding music.
