Recording - February 2018 - 70

STUDIO 101

PART 2

Storing Audio-

From Analog To Digital

elcome back to Studio 101. In our first chapter, we covered the basics of audio as pressure waves, and converting those waves into electricity. We saw that we must perform such a conversion to make it possible to store
the sound, since storing and retrieving audio is the heart of the recording arts. But a question remains: how
does storing audio actually work? To get a better understanding, it is useful to dive into the history of audio storage-we
can learn how earlier technologies worked, and will see why the advent of digital audio was such a game-changer for
recording enthusiasts.
BY DARWIN GROSSE

Historical Audio Storage
The earliest methods for recording audio dealt most directly
with the physical nature of sound. Early recorders were huge
cones that collected sound pressure waves and forced a stylus
to scratch a facsimile into a somewhat soft surface (typically,
a cylinder of wax). As recording technology progressed, microphones converted sound into electrical signals, which were
then used to drive a motor-driven cutting head. This more powerful cutting system allowed for new kinds of physical media,
with vinyl becoming a preferred platform for music distribution.
But recording to vinyl has some serious limitations. First,
it requires many steps between the source and the product,
often requiring a record pressing plant to make even a few
copies of a recording. Second, vinyl is relatively fragile: after
only a few plays, discs begin to show wear, lose some of their
frequency range, or even add clicks and pops that could spoil
a good recording. But most importantly (for us), these physical
recordings are completely fixed: there isn't any ability to edit
the audio once it had been scribed onto disc.
So, if you were after either portability or editability, nothing
about disc/cylinder recording was optimal. Luckily, as recording
systems became electrified, inventors began finding new ways
to store the electrical audio signal. Recorders were born, first
recording on wire reels, but eventually to magnetic tape. These
tapes-a plastic strip coated with a metal-oxide coating-proved
to be a winning medium for recording. The tape stock was
inexpensive to produce, could replicate audio with good fidelity,
and was easy to edit using a razor blade and editing block.
Of course, it wasn't without problems of its own. First, the
coating held a physical version of the sound wave-it was the
sound wave as it was transformed into an electrical signal, but
now the pressure wave patterns were stored on tape as areas
of varying magnetization. This magnetization wasn't flawless,
and there was significant coloration to the sound that was recorded onto tape. Tape also had physical limits to the levels
that could be recorded-a feature that many producers took
advantage of, for adding a warm distortion to their recordings.
But perhaps most problematic was the tape itself. The
formulation of the metal-oxide coating, as well as the chemicals
used to bind the coating to the tape, began to break down
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RECORDING February 2018

with age. Old recordings will sometimes flake off the tape
backing during playback, requiring careful preparation of the
tape reel to minimize inevitable damage. Not great news!
The next important recording revolution came with the digitization of sound. Digitization changes everything, since you
are no longer directly storing pressure waves. Rather, you are
encoding audio into a block of ones and zeros, then storing
them in some convenient way. In the early days of digital audio,
it was most cost-effective to store the digital data on tape, but
this had its own problems: tape is still fragile, and if you had a
problem with the tape, it was unlikely that you could retrieve any
digital data at all. On the other hand, if you could read the tape,
the sound would be virtually as good as its initial recording.
Digital tapes also tended to be professional equipment, and a
different medium needed to be created for distribution to the public.
Hence, the CD-the tool that helped us all re-purchase our Steely
Dan record collections, and introduced the public to digital audio.
For recording enthusiasts, things went in a different direction:
digital recording software started becoming available, and music
got stored onto computer hard drives. Now it's difficult to avoid
having a stack of drives for your music data, since it is faster and
cheaper to have backups on hard drives than putting them on
CD or tape. Currently, I have a portable 2 Terabyte drive that is
cheaper than a few packs of CD blanks, holds much more data,
and can be accessed with no reduction in performance. This
helps us understand why digital audio-and the computer-have
become the dominant tools for audio recording and storage.

The elements of digital audio
Digital audio is now ubiquitous. Go to your local audio retailer
and ask for a tape-based system and unless there's a used
cassette 4-track gathering dust on some shelf, you'll just get funny
looks. On the other hand, the number of options for digital
audio production can be overwhelming. Determining what you
need-and what the capability of the hardware is-requires
an understanding of a few concepts surrounding digital audio.
The first thing to understand is how digital recording works.
It is based on the idea of sampling, which is roughly the sonic
equivalent of shooting a movie. In short, you grab many individual snapshots of the sound, then stitch them together to create a

Table of Contents for the Digital Edition of Recording - February 2018