Digital sound vs. analog sound: what’s the difference?


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It is very common to hear about digital sound. This wave of digital sound comes from the late 1970s, when digital media began to appear on the market, further solidifying with the arrival of CD in 1983. Leading brands would begin to announce digital sound as the great revolution in Sound. Recently, however, many have decided to go back to vinyl or even analog cassette tapes and claim that the sound of analog media is superior to that of digital media. But who is right?

Digital and Analog Audio

First, let’s establish that, when we talk about digital sound versus analog sound, we are mainly talking about the media where that sound is stored and the encoding used in those media. With that, we can start by classifying them by saying the following:

Analog sound is all that sound placed in uninterrupted media, creating a change in the media that is analogous to the phenomenon of sound. In the case of vinyl, a groove similar to the electrical signal generated in the microphone is created. In the case of magnetic tape, there is a change in the magnetic field analogous to the electrical signal generated at the microphone.

Analog and Digital audio

Digital sound is all that sound placed on media encoded in binary code. This encoding transforms the microphone signal into a digital code that follows various parameters, such as the Nyquist theorem, sample rate, bit depth, bit rate, interpolation, etc. In future publications, we will study each of these characteristics. Examples of digital media are: CD, SD memory cards, SSD, HDD, DAT … In short, everything that can store a digital code.

Some authors argue that all sound is analog. However, according to the previous definition we will establish that the sound, in itself, is natural. Each natural sound that reaches the microphone becomes analog by generating an electrical signal. And each microphone will start as analog. There are some digital microphones, but these are nothing more than microphones that have an analog / digital converter in their structure, making the sound emitted digital. In addition, all speakers also output analog sound only, since even if the source is digital, it will be necessary to perform a digital / analog conversion in any situation.

That is, the sound has to be analog at any given moment in the capture / playback chain, but it doesn’t necessarily have to be digital. That’s why many argue that analog sound is “pure” and, according to some people, “better”. However, there are several advantages to digital media. For example, digital media is more accurate, has a better differentiation between channels, is more compact and cheaper.

In productive terms, digital media outperforms analog media in several ways. Therefore, it is quite rare today to find analog sound in film and music. The logistical approach between analog and digital is different and many artists maintain that the use of analog media directly influences creation, since many feel that in analog there is a greater intimacy between the artist and the physical phenomenon. But in general, we can associate this intimacy only with the subjective factor. Analog is more expensive and offers a result that can be copied to digital.

On the other hand, there is a good advantage for analog media: durability. In general, vinyl and tape, if well maintained, have greater durability than CDs, DVDs, or HDDs. Until now, we still do not have a digital medium that has proven to be resistant to time (with the exception, perhaps, of DAT). Also, the way the viewer relates to the media is very important. In this case, the imperfections of analog media can make it more intimate and the precision of digital media can make it cold and impersonal. It goes for each one.

The most important topic of discussion on this topic in the world of audiophilia is related to CDs vs. Vinyls, a point that we will address in greater depth in some future publications. But for now, this is what we have about digital sound versus analog sound.


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ANALOGUE AND DIGITAL

The essential

Analog and digital are two methods of transporting and storing data. (audio, photo, video …). Analog was born with the onset of electricity, while digital appeared more recently in the computer age.

Analogue and Digital

The analogical principle is to reproduce the signal to be recorded (audio, video …) in a similar way in a medium (magnetic in general). For example, when recording an audio signal in an analog system, the signal present on the tape will follow the same amplitudes (“the same curve”) as the sound wave (with more or less fidelity): the characteristic pressure variations of a sound wave will result in variations of an electrical signal. Therefore, the electrical amplitude of the analog signal will be the more or less faithful image of the signal to be recorded (audio, video, etc.)

analogue vs digital

In digital, the analog signal to record becomes digital thanks to an analog> digital converter. After this conversion, the signal is just a sequence of “0” and “1”, that is, a signal with two amplitudes instead of infinity in analog.

Once in this form, the signal can be copied and transmitted losslessly because instead of transporting a signal whose amplitude should faithfully vary from the original, it carries a signal consisting of only two amplitudes (for example, 0 = 0 volts and 1 = 5 volts). So when a parasite disturbs an analog signal, digitally this parasite will have no effect: for example, a parasite that adds 0.2v disturbance will deteriorate an analog signal, while this same parasite on a digital signal will have no effect because 0v + / – 0.2v will always be considered = “0”.

Therefore, the digital signal is an analog signal made up of two possible levels (for example, “0” = 0v and “1” = 5v) and when the analog signal moves away from these two voltages, it does not matter because all the signals close of 0v will be considered = “0” and any signal close to 5v will be = “1” with a voltage threshold between the two resulting in exceptional immunity against parasites and exemplary ease of making perfect copies (clones) of this signal type.

After digital transport and storage, any signal (video or audio) must return to its original analog form. For example, an audio signal will be converted from digital to analog and then amplified; in fact, our ears cannot hear digitally! ! !

It should be noted that digital is only used (in the case of an audio or video signal) for the transport and storage of data.

2 / Analog VS Digital and data compression.

So we have just seen that digital is not a commercial device, it is the support of all new technologies, but should we consider that digital is definitely better than analog?

I would try to answer yes, but it is necessary to moderate this judgment and that for two reasons: compression and sampling.

* / Digital compression:

Converting a signal to digital is not without problems: the bandwidth occupied by a signal once digitized is greater than its analog equivalent. When dealing with very bulky data, such as video, the processing is very cumbersome; Therefore, it is necessary to use a compression algorithm intended to reduce the amount of information by reducing the quality of the signal. All of the compressions used for video or audio rely on human perception to make this drop in quality little or not noticeable to humans. But the problem is that we often tend to want to compress the signal too much and the degradation becomes noticeable (case of GSM phones, MP3 <128kbit / s, mpeg-1 videos …)

For example, a high-quality audio signal recorded on a high-end cassette deck (analog) will be of better quality than a 112kbit / s mp3, because a large amount of information has been suppressed at 112kbit / s to satisfy the 112kbit / s imposed bit rate.

On the other hand, in an analogous way, the concept of copy generation intervenes: one copy will be less good than the original, one copy of the copy will lose a little more … After 10 or 20 copies of copies, the signal is totally deteriorated and cannot be used. In digital, a copy is often a clone of the original, so in theory you can make countless copies that are strictly the same quality as the original. I am talking about theory because errors can occur during a digital copy, often due to the state of the media. This is the case when copying an audio CD digitally (from your CD-ROM drive to your hard drive, for example): when a scratch or failure occurs, the information will not be copied and will be replaced by the correction system errors due to “extrapolated” data make this defect go unnoticed; In this case, the digital copy will no longer be identical to the original.