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Understanding Analog & Digital In Terms Of Audio

Neither is "better" or "best" -- an uncolored look at the underlying simple truths of both formats...

By Bruce Jackson & Steve Harvey June 26, 2018

But in the recording process today, you have almost no choice regarding staying in the analog domain if you plan to release the project commercially. At some point in the process you must convert into the digital domain, if only for the release format, if you hope to have any kind of financial success.

But even the benchmark set by CD has been lowered with the current downloading revolution. The very nature of an MP3 file dictates that the listener is missing something. MPEG compression is a ‘lossy’ method; that is, it throws away what it considers to be insignificant content when compressing the file size.

But perhaps it’s throwing away that indefinable something that analog aficionados cherish.

Perhaps more significantly, the MP3 revolution may be leading to a generation that has no concept of distortion. A few years ago, an engineering acquaintance related how he had to sit his son down and explain distortion to him.

At the risk of sounding like an old fuddy-duddy, kids today are used to hearing “crunchy” audio. Younger people who have only lived during this digital era are largely unaware of ‘good’ distortion, the acceptable harmonic distortion of analog audio.

To them, what we consider bad digital distortion is simply a part of the music that they listen to daily. Trading poorly “ripped” MP3s (regardless of legality), they have become so used to the crunchy sound quality of the format that, as some readers who have discussed the matter with their own children may attest, they may find it not only acceptable but even preferable to CDs.

The crunch of digital distortion, which is not limited to MP3s, of course, but can just as easily find its way into the digital recording process and onto disc or into the live sound arena, is unpleasant.

The pops, clicks, and surface noises of the vinyl beloved of audiophiles pale by comparison to the harsh distortion of digital audio, compressed or uncompressed.

Right & Wrong?

With digital audio, noise and distortion tends to be inharmonic and unrelated to the original sound, whereas analog distortion is harmonically related and may be pleasant or, in extreme cases, tolerable. Analog distortion can add a hard-to-define “warmth” to a sound.

Is wrong always wrong? Analog distortion can even be a major component of a sound, such as an electric guitar, and therefore desirable.

If you run audio through a tube device, you are doing it to add flavor, not to reproduce something exactly or realistically. In such cases, the audio process may not be accurately recreating the original source, but it is at least adding partials that are music-related, and therefore relatively harmonious.

There’s a reason why old mixing consoles, such as those designed and built by Rupert Neve, for example, are so sought after. The “warmth” controls on Mr. Neve’s contemporary updates of his old designs actually introduce a modicum of distortion.

This was something that was inherent in many of his original designs, albeit at low levels, yet which could impart an emotional response to the music produced through the equipment that made it attractive to the listener.

In the analog world, distortion is usually related to the original sound. The transistors, op amps, resistors, capacitors, and inductors can add even or odd harmonics. These unwanted extra harmonics are related to the original sounds in evenly spaced octaves.

If the distortion is in even multiples, taking the example of a bass note of 100 Hz, adding distortion at two times or four times the original and so on, the harmonics at 200 Hz, 400 Hz, and up tend to sound warm and on the organic side.

Odd harmonics, such as those at three, five, and seven times the original, tend to sound hard and edgy. But whether even or odd, they are generally somewhat ‘musical.’

The types of distortion picked up in a digital signal path are often unrelated harmonically to our pristine audio. Those unwanted aliases in the analog to digital conversion are inharmonic and sound just plain awful. And once they are in there, there is no getting rid of them.

But there are many different types of distortion—harmonic, intermodulation, frequency, phase, time, and so on, that are frequently present simultaneously and therefore interrelated. And not all are pleasant.

Ultimately, the goal in any audio system, analog or digital, is to maintain the lowest overall distortion.

Modeling In Digital

Byproducts of a compressor moving too fast in the digital domain can splatter grunge all across our good sound. Done with care, the same process can sound pleasant, like the analog equivalents.

Using a compressor as an example, it’s often hard to model what goes on in an analogue compressor in the digital world.

Analog designers often choose a simple gain control element that consists of a module with a light shining on a light dependant resistor. As the light comes on, it reduces the level of the audio flowing through the resistor.

But the resistor is slow to respond to the light. If a loud passage comes along and the light brightens to reduce the level, some of the loud stuff sneaks through while the sluggish control element changes.

It is also slow to come back to where it started after the loud passage has passed. Additionally, it adds subtle even order harmonics.

Going back to our food analogy, modeling the nice sounding analog compressor digitally is like trying to capture all the subtlety of the vanilla bean. Artificial vanilla has the same basic chemical composition as the real thing, but tends to lack the many subtle additional flavors and aromas that make real vanilla what it is.

Manufacturers offer compressors using inexpensive light dependent resistors for many thousands of dollars. When we run analog audio through digital equivalent, we want the designer to capture all the subtle nuances of our funky analog unit.

Digital designers claim to accurately model the analog world, but just like our lowly vanilla bean, it’s not that easy. What digital audio equipment most certainly offers is precise control and repeatability. Extensive recall of presets is technically much easier in digital.

Yet some users will still pick analog equipment because quality of sound outweighs the easy life of presets.

In equipment like digital mixing consoles, dynamic and snapshot automation allows the near instantaneous reset of console-wide, complex setups. That can be a particularly useful feature when the front-of-house console is handling multiple acts in quick succession, to offer just one example.

Similarly, on a major tour that is using in-ear monitor systems, which are not greatly affected by the nightly change of venue acoustics, setup times can be drastically reduced. Digital consoles such as those made by DiGiCo, Yamaha and Digidesign offer varying levels of features and price.

Digital processors let you do things that are otherwise impossible in the analog domain, such as impossibly steep-sided filters and multiple EQ curves stacked one on top of the other. Alternatively, there is the hybrid approach, digital control of analog circuitry, which several console manufacturers experimented with in the early ‘80s.

This article originally appeared on PSW in 2014. The late Bruce Jackson was involved with several leading audio companies and mixed Elvis Presley, Barbra Streisand and Bruce Springsteen, among many others, over the course of his illustrious career. Steve Harvey is a widely published professional audio journalist.

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Kevin Chand says

Digidesign, now there's a name I know and love (and don't exist anymore). Good primer article. Please like my facebook page @thenexusllc :D

HalfSpeedMastering says

the laws of physics forbid reaching 0 or 100%, No power supply will ever be 100% efficient, today the best are 94%-96%, Science has never reach 0° temp, it can get close, but never 0°, also OFC copper cables: 99.9999997% 8N copper, but Never 100%., Gold Bars: 999.9 Never 100,0 Digital Nyquist degrades with frequency. at a SampleRate of 44.1Khz, a Square wave lower than 5.5KHz is very close to 100% emulation, the lower the closer, but over that frequency becomes less & less accurate, a 20KHz square wave, looks near 100% distortion or Near 0% emulation at 44.1KHz SR.
digital is an emulation, & plugins are an emulation inside an emulation. assuming the best plugin manufacturers have an emulation 95% perfect, in some cases that extra 5% will be 10x the price.. plugin vs. hardware.
is Not the same A/B: analog vs. digital, vs. analog digitized.
is it worth that 5% of digitized analog? depends on the listener, wax level on the ear, loudspeakers, DA, cables, power, etc... some people wont hear a 5% difference... others hear a night & day... depends on the day, the ear gets tired, like muscles, some days i hear night & day, some days i hear my pocket. LOL.
most plugins are designed to be transparent sounding, makes real analog sound Dated/old, but HW can be modified to sound transparent ...
HW cannot be bounced faster, must be realtime, for some jobs thats No Go.
EQ´s can be emulated very close, some analog noise floor without power cleaners is around 18-bits Dither Apogee, most AD&DA are 20-Bits noise floor, but HP&LP filters, Compressors, Tape & Tube equipment are Not as close, example: all 12ax7 brands sound a bit different, they change organically, like moving waves, most digital emulations are like a photograph of that moving sea of electrons breathing, CPU power vs. accuracy curve, 1% more accurate is usually 100% more CPU. HW is a lot more expensive, people buy plugins 1st, then make A/B test to compare, to find the sound they are looking for, its like pizza, the same pizza tastes different in different stores, but some brands are very similar.... some brands have a unique pizza, that is what most people "that hear a Night&Day difference" are looking for.
because HW is more expensive, makes more sense in Mastering...

HalfSpeedMastering says

also there is another problem, HW emulations are usually besed on different Hardwares, and HW have component tolerances, cheaper components have a high tolerance +/-20%, but precisión components have a 1% or less tolerance, the same resistor can be $1usd or $1000usd. each... age, different ac power, component tolerances can make the same HW sound very different, with some exceptions.. rare fairchild compressor are so rare that plugin developers usually rent the same unit, to make the emulation, but different ac power, different converters... Also there is the quote: using right tool for the right job, a single screwdriver cannot do it all... for rap & pop vocals a medium to high THD equipment is more desired tan ultra low THD equipment... more dynamic, or less dynamic, more transparent, or more colored/less transparent, selecting a swiss army knife or hand picking HW to make your own signature sound, that defines your brand/taste/personality, is not purchasing for purchasing, like John Deere vs McLaren/Lamborgini, one is slow, the other fast. LOL. having the right tool for the job is very important... for example MCI jh-426 mic-pre sound very unique, that sound is very interesting for some music styles, but dull for others... having all the tools in HW is very expensive, but in plugins is very easy, for mastering a signature sound or a transparent sound, some music styles sound alien with the wrong color/tool. running in high heles, or using lamborginis in the farm, is just wrong. LOL...

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