The debate between analog and digital audio is very polarizing. Many people take one side
and defend it without leaving any room for nuance in the center. The truth is,
however, that both have advantages and disadvantages and in this video
I hope to give you an unbiased explanation of the differences.
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Before we begin discussing the differences between analog and digital, I think it's really important
to point out one thing - every digital system utilizes analog technology. So microphones,
preamplifiers, power amplifiers, speakers, and many other things are analog technology.
And so a digital system that's 100% digital does not exist. The primary focus of this
video will be the differences between analog and digital recording technology.
Let's start with analog audio. Magnetic tape is the best, most high-quality method for analog
recording and playback. It works in the following principle: When an electric current is sent
through a wire, a magnetic field forms around the wire and vice-versa. The record head on a
tape machine is an electromagnet, meaning that it's magnetic field alternates with the current
that runs through it. The electrical signal from a microphone is sent through the electromagnet
which creates a magnetic field that resembles the sound wave captured by the microphone. As the tape
passes through that magnetic field, the particles along it are magnetically charged. The pattern of
magnetic charges along the tape now resembles the sound wave captured by the microphone initially.
To play back the audio, the process is just reversed. The quality of analog tape recordings
is primarily determined by two factors - tape speed and tape width. Tape speed is measured
in inches per second or ips. The standard for professional recording is 15 to 30 inches per
second. Tape width can be utilized in one of two ways. Either it improves the sound quality
of a single channel or you can create multiple tracks along the same tape so that you can record,
independently, different instruments. The logistics of mass-producing analog tape to
be played back on reel-to-reel machines by the consumers is in practical. Vinyl records are
much easier to maintain and distribute and unlike tape they're not vulnerable to being destroyed by
magnetic fields. Rather than magnetic charge, grooves along the vinyl record store the audio
information. As the record spins, a stylus travels through the grooves. The movement
of the stylus creates an electric current on an electromagnet which is connected to an amplifier
to power speakers. Analog recordings are made with tape and then pressed to vinyl for distribution.
Now let's discuss digital audio. PCM, or pulse code modulation, is the primary method used to
store audio signals as digital information. PCM creates a model of sound waves by storing
a sequence of numerical values that represent the amplitude or intensity at various points
along the wave. These values are stored as groups of bits called samples and this process is called
quantization. The two main factors that determine the quality of digital recordings are bit depth
and sample rate. Bit depth describes the number of bits used per sample. Each bit can represent
two values - on or off. Each time you add a bit you double the amount of possible values that
that sample can represent. This adds up pretty quickly! One bit offers two possible values,
two bits offer four possible values, three bits offer eight possible values, and so on. The
standard for CDs is a 16-bit depth. That's 65,536 values! Most professional studios record at 24-bit
number of samples taken per second. The Nyquist theorem states that you must sample a wave at
twice the frequency of the highest frequency you wish to record. So if we want to record 20 kHz,
which is the highest frequency humans can hear, we need to sample the wave at at least 40 kHz.
That's why 44.1 kHz is the standard for CD-quality audio. Many studios record at a sample rate of 96
kHz and higher. The audio files created by studios are very large. A three-minute recording created
with 24-bit depth and 96 kilohertz sample rate would be about 52 megabytes. This is
just too big to be practical for consumer uses such as streaming, and for that reason we use
data compression. There are two types of data compression - lossy and lossless. I'm gonna go
into much more depth in a different post, but what you need to know is that if information
is lost during the compression, a lossy format is used. Now remember that when using a lossy format,
once data is destroyed it can never be restored. Although lossy formats do destroy information,
they try to prioritize which information to destroy based on the way humans perceive sound.
If no information is lost during the compression, a lossless format is used. Lossless files can
preserve perfect audio quality but they're also much larger than lossy format files.
Now that you understand the methods used by analog recording and digital recording technologies,
you understand that there's a common goal - to create a model of a sound wave that can
be played back later. Each method does this pretty well, but in this section
I'm going to show you the key differences, the drawbacks, and the advantages of each method.
audio is portrayed as this square wave, but in reality the samples are just points in time,
so the waveform created by digital audio recording is not as jagged as some people make it seem.
The major drawback to tape, however, is the noise floor. You hear hiss in old recordings,
and that's because there's always an inherent noise associated with magnetic tape. The
theoretical noise floor of a 24-bit digital recording is -144 dB - that's effectively no noise
floor. Now of course, keep in mind that every single digital system uses analog components, and
so the inherent noise of those analog components can add up just like it would in an analog system.
Another key difference is longevity and vulnerability. Not only do analog
media contain inherent noise from the beginning,
but they're also much more susceptible to degradation over time.
The final difference and the reason why digital audio has taken the world by storm is portability
and reproducibility. One digital recording can be made and then copied an infinite amount of
times. It can be shared with the entire world at very little cost across the internet. To do
that with analog recording, you would have to create miles worth of tape or
thousands... millions of vinyl records. Then you'd have to manufacture each one
separately using very expensive machines. Digital audio is much more economical.
So that sums up the main differences of analog and digital recording. However,
there are other uses of analog and digital technology. The two
main differences between analog and digital and live sound are latency and portability.
Every digital system adds some bit of delay in the signal chain called latency. This
can cause problems in the form of phase interference or more commonly monitoring.
If a musician is monitoring themselves through headphones and there's a delay
caused by the digital system, it can be very confusing to the musician.
The reason why digital audio dominates the live sound industry as well is, again,
because of portability. Within the size of one digital mixer, an engineer has the
ability to do almost infinite processing on hundreds of channels. To do that same thing
with analog gear would require racks and racks of equipment that weigh thousands of pounds.
Noise floor also plays into this equation. Because digital processing occurs inside one box,
you're not daisy chaining equipment together like you would with analog. As you daisy chain
more and more equipment, you're summing the inherent noise from each of those devices.
The truth is that digital and analog technology have value, even in the modern world. Each
one has its drawbacks, each one has its advantages, and it's up to us as audio
engineers and musicians and listeners to decide which technology is best for our circumstances.
I really hope that this video has been helpful. If you've gotten value out of this,
hit the "Like" button for me. If you want to learn more about the
fundamental concepts and tools of audio and how to apply them,
subscribe to my channel and check out my blog at AudioUniversityOnline.com. Thanks for watching!