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2.2 Content media

2.2.1 Analog mode: Audio


In recent decades, museums have accumulated considerable audio material in various analog formats. It is recommended that these analog collections be migrated to digital before it is no longer possible to find equipment that plays analog audio tapes. Fortunately, migrating these outdated formats to digital is an easy task.

Analog audio tapes present the same deterioration problems as analog video (noise, distortion, creasing, etc.) and must be conserved in the same way as video.

The best practice is to migrate analog material to an appropriately equipped computer, taking care to apply a sampling rate of equal or preferably higher quality than that specified for the compact disc (CD), i.e. a sampling frequency of 16 bit/44.1 kHz, as recommended by the Red Book. [1]


Audio cassettes (compact cassette)


Compact cassette

The audio cassette is the most common analog tape format. Introduced in 1963 by Philips, this format dominated the commercial recorded music market until the early 1990s, when it was replaced by the compact disc (CD). The audio cassette held many advantages over the fine groove record (its main competitor). It was less fragile; when combined with a player it became a portable system; and above all, it was the taping device most employed for household use. The possibility of taping at home with relatively inexpensive equipment also made the format very popular among artists. Today, most museum collections are comprised of this unstable format, which is now becoming obsolete.


Fortunately, it is still easy to obtain audio cassette players (used and new), and it is likely they will continue to be available for many years to come. [2]

For works where the audio equipment is visible and the cassette plays a significant role, simple digitization is not enough. In these cases, new exhibition copies must be made to ensure the work’s longevity and future use. It is recommended that this process begin with a document that has been stabilized using a computer. The procedure consists of digitizing the cassette at a high sampling frequency and resolution, then, using the new audio document, creating multiple exhibition copies in audio cassette format. This course of action has the advantage of being both simple and inexpensive.


Another use of the audio cassette


In the 1970s and 1980s, the audio cassette was used in the microcomputer sector as a replacement solution for expensive floppy disc drives. The audio cassette was used to store digital data transformed into modulated analog sound. When digitizing these cassettes, it is recommended to quickly stabilize this data, as the system itself is unreliable due to reproduction problems, which in turn can create problems interpreting analog signals. [3] The only difference in the digitization procedure for these cassettes is that it is even more important to use a higher resolution and sampling frequency.

When acquired by the MBAC, UNEX Sign No. 2 by American artist Jenny Holzer included audio cassettes on which were stored the programs needed to operate the electronic sign. In 1991, the cassettes were migrated to floppy discs.


[1] The Red Book is a publication produced in 1980 by Sony and Philips that contains all technical specifications for the CD and CD-ROM formats.

"Red Book (audio Compact Disc standard)", Wikipedia, http://en.wikipedia.org/wiki/Red_Book_(audio_CD_standard).

[2] Almost all manufacturers have produced one or more audio cassette player models in past years, inundating the market and assuring the availability of this equipment for some time to come.

[3] Digital Preservation Management, "Chamber of Horrors: Obsolete and Endangered Media:Tapes", http://www.icpsr.umich.edu/dpm/dpm-eng/oldmedia/tapes.html and Apple2History, "History", http://apple2history.org/history/ah02.html.