A digital audio project drawing exclusively on a compact disc collection requires no equipment other than a computer with a CD-ROM drive. Most libraries, however, are digitizing analog recordings as well as compact discs, and these formats require additional components to play back the recordings. The components are usually patched into a mixer or amplifier, which in turn is patched directly into the computer's sound card or audio interface. To work with tape recordings, components are added that are appropriate for playback of tape through a traditional sound system--for example, a cassette, reel-to-reel, or DAT deck.
The quality of sound that can be reproduced from older analog recordings will depend on the condition of the recording and the quality of the component playing it. Libraries that have been providing listening services for several decades will have turntables and tape decks that are probably, at this point, underused and can be co-opted for the digital audio project.
The high-quality playback that is essential to preservation work can be provided only by high-end components, and some are designed with preservation in mind. A laser turntable, for example, allows playback of an LP or 78 without contact with the disc, so repeated playback results in no wear whatsoever.
The equipment configuration used for most digital audio projects consists of a computer with a CD-ROM drive, a turntable, a cassette deck, and an amplifier.5.6 The analog recording format most frequently digitized by libraries is the LP. Eighteen (58 percent) of the thirty-one survey respondents have a turntable devoted to their digital audio project. Next in frequency, with fifteen (48 percent) is the cassette deck. After that, the numbers fall off sharply. Three libraries use DAT decks, and two use reel-to-reel decks.
Some compact discs cannot be read by a computer's CD-ROM drive. This is most often occurs with older compact discs. These discs must be played on a traditional compact-disc player, which is patched into the system as if it were a turntable or tape deck. Two of the survey respondents have independent CD players devoted to their digital audio projects.