AKARSH SHEKHAR
Digital vs Analog : Dawn of Fidelity
Analog-to-digital and digital-to-analog converters are both crucial components of audio systems . Often they tend to be taken for granted . As long as your interface is feeding audio into your DAW , you probably don ’ t think much about analog-to-digital conversion — or the digital-to-analog converter that ’ s driving your monitor speakers . And when you ’ re playing a digital synthesizer , the digital-to-analog converter that lets you feed audio into an amp is likely not getting much mindshare . To understand analog-to-digital converters ( ADC ) and digital-to-analog converters ( DAC ), we need to review some audio basics . Sound consists of variations in air pressure , which have peaks and troughs like ocean waves and interact with our ears ’ hearing mechanism . The information our ears receive travels to the brain , which processes the information . All audio , from an annoying barking dog to a symphony orchestra , is a wave with a varying shape and level . Often , the more complex the sound , the more complex the wave ’ s shape .
What is Analog Audio ?
Carving a waveform ’ s outline into a vinyl record creates the record ’ s groove , which looks like a valley under a microscope . When the record plays , the stylus follows this waveform , which causes the phono cartridge to generate voltage variations analogous to the sound ’ s original waveform which eventually drive a speaker . Because the speaker cone follows the waveform motion , it reproduces the same waveform originally pressed into the vinyl record . Note that each stage transfers a signal that ’ s analogous to the input signal — hence the term , analog audio .
Unfortunately , just like band members , analog audio has limitations . For example , a vinyl record ’ s pops , clicks , warps , and surface noise are added to the original sound as undesirable audio “ artifacts .” A phono cartridge adds its own coloration , dust causes pops and ticks , tape recording adds hiss , and so on . So while the signal appearing at a speaker ’ s output may be similar to what was originally recorded , it will not duplicate the original sound exactly , due to the errors inherent in analog recording , processing , and playback .
Why Do Digital Audio Maintain Fidelity ?
Consider the compact disc , which stores digital data on a plastic disc . A laser reads this data and then sends it to a DAC that converts the data back into analog . CDs use error correction that can figure out and replace missing data if there ’ s a minor scratch on the disc , which makes them less likely to skip . When downloading music , even if there ’ s an interruption in your internet connection , a properly designed download engine will assemble the pieces into a file you can play back without interruption .
Even more importantly for musicians , using digital audio preserves quality as audio goes through the signal chain . In the days of analog multitrack recorders , you mixed your song down to an analog 2-track tape , and this introduced additional hiss and distortion . Mastering the tape added more chances for error , as did transferring the audio to a metal stamper that could press records ( which in turn could introduce pops , record wear , and warping ). At each audio transfer stage , the signal quality deteriorated .
Digital Audio Limitations and Solutions :
When the CD first appeared , it was promoted as “ perfect sound forever ” — don ’ t you just love marketing ? But digital audio , while generally better than analog audio , still isn ’ t perfect due to these limitations :
» Sampling rate issues » Output filter coloration » Resolution ( quantization ) errors » Nonlinearity » Dynamic range limitations » Jitter » Offset and gain errors
» Although digital audio may not be perfect , it continues to improve . However , just because something is “ digital ” doesn ’ t automatically mean you ’ ll enjoy all the benefits of digital audio . The converters in your smartphone or other consumer devices will not have the same level of quality as converters intended for pro audio .
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