About the National Jukebox
Making the Jukebox

Using catalogs, microfiche indexes and even browsing through cart-loads of records, a project curator selects discs for the National Jukebox from the Library of Congress collection and compiles final lists of selections.

Technicians pull all copies of each Victor 78rpm disc matrix/take combination working from the lists assembled by curators.

Technicians use magnifying lamps to examine the grooves of every disc. All of these discs are of the same recording (i.e., same matrix/take combination), but only the best copy is selected for digitization.

A slip that provides the elements of the filename of the digital copy is inserted in the sleeve of each selected disc: institution/collection code, label name, label number, disc copy, matrix number, and take number are all noted on the slip. Using a naming convention that combines these elements allows each individual side to be fully and uniquely identified by the filename.

Once selected, the discs are then delivered to a special room at the Packard Campus designed for disc cleaning. On the disc cleaner turntable the discs are treated with a mild solution of Tergitol and distilled water, scrubbed gently with a soft brush, and vacuumed dry. This is repeated using only distilled water to rinse off any residue. Once both sides are cleaned and rinsed, discs are re-sleeved in archival jackets.

Once selected, the discs are then delivered to a special room at the Packard Campus designed for disc cleaning. On the disc cleaner turntable the discs are treated with a mild solution of Tergitol and distilled water, scrubbed gently with a soft brush, and vacuumed dry. This is repeated using only distilled water to rinse off any residue. Once both sides are cleaned and rinsed, discs are re-sleeved in archival jackets.

Each disc has to be searched and claimed in the project database. A barcode readable filename label is printed for each selected side and attached to the sleeve and the copy number of the disc is written on the sleeve. Barcoded discs are put on a designated holding shelf then delivered in padded carts to an audio preservation studio for digitization.

In the studio, the engineer checks the slip to determine the side or sides to be digitized and the correct barcode that should be scanned for each side.

Careful handling of shellac discs is standard conservation procedure. The label information is double-checked under a lamp when the disc is put on the turntable.

Here is a cued up 78 on the turntable in the preservation studio. Note the large set of styli kept on hand. The brush and cleaning solution are for cleaning the styli as needed. Since neither speed nor groove size were precisely consistent in the acoustical era, the initial stylus and speed setting in the studio is a best guess estimation. Because the discs coming to the studio are typically batched in label number series, they may also have similar playback speeds and groove sizes. So the engineers usually start with the settings that were used in the previous transfer then use their trained ears and studio experience to determine what changes are needed.

Here is a cued up 78 on the turntable in the preservation studio. Note the large set of styli kept on hand. The brush and cleaning solution are for cleaning the styli as needed. Since neither speed nor groove size were precisely consistent in the acoustical era, the initial stylus and speed setting in the studio is a best guess estimation. Because the discs coming to the studio are typically batched in label number series, they may also have similar playback speeds and groove sizes. So the engineers usually start with the settings that were used in the previous transfer then use their trained ears and studio experience to determine what changes are needed.

During the initial playback, the audio engineer sometimes uses a keyboard to fine tune the speed / pitch adjustment. In the acoustical era, particularly the early years, there was significant variation in the speeds of the machines used to record sessions in the studio. A good ear, a pitch generator, and a variable speed turntable are essential for proper playback of these discs. Occasionally the spindle hole in the record is off-center and the engineer must manually center the record to make it spin properly on the turntable.

The final step before beginning the transfer session is to determine the optimal stylus to use. After listening with the initial stylus, the engineer tries the next size up and down and even different shaped tips to determine if the sonic quality improves with either a smaller, larger, truncated, conical or elliptical stylus. The goal in selecting a stylus is to maximize information and minimize distortion. This is accomplished when a stylus rides on the least worn portion of the groove, without touching the bottom where dirt and debris can collect. Factors such as the age and manufacturing of the disc, as well as the amount of groove wear can influence what size and shape of stylus works best.

The final step before beginning the transfer session is to determine the optimal stylus to use. After listening with the initial stylus, the engineer tries the next size up and down and even different shaped tips to determine if the sonic quality improves with either a smaller, larger, truncated, conical or elliptical stylus. The goal in selecting a stylus is to maximize information and minimize distortion. This is accomplished when a stylus rides on the least worn portion of the groove, without touching the bottom where dirt and debris can collect. Factors such as the age and manufacturing of the disc, as well as the amount of groove wear can influence what size and shape of stylus works best.

The preservation master audio files are created to international standard 24 bit / 96 KHz Broadcast Wave format. Even though the disc is a monaural recording, the initial transfer is made in two channels to capture both walls of the record groove. Looking at the wave form on the digital audio workstation enables the engineer to check the peak frequency levels for over levels and compare the amount of noise in the two groove walls.

Next the two channel file is summed to monoaural on the digital audio workstation. An access copy in Broadcast Wave format, is produced from the master mono file at 16 bit / 44.1 KHz resolution. Filenames for both master and access files are assigned by wanding the barcode label. The use of a barcode readable filename system prevents keying errors that tend to plague manual entry processes.

Next the two channel file is summed to monoaural on the digital audio workstation. An access copy in Broadcast Wave format, is produced from the master mono file at 16 bit / 44.1 KHz resolution. Filenames for both master and access files are assigned by wanding the barcode label. The use of a barcode readable filename system prevents keying errors that tend to plague manual entry processes.

On a weekly basis, master audio files are moved to the Packard Campus digital archive and the access files to a Library of Congress server on Capitol Hill.

A final check of the folders and filenames results in the creation of spreadsheets for scanning labels and correcting filename problems.

Here a Technician is checking filenames against the completed discs to resolve possible conflicts.

Scanning a 78 side. Master images are 400 dpi TIFF files; from these, 728x728 JPEG and 60x60 thumbnail images are generated for use on the web.

Finally, 320Kbps and 128Kbps mp3 audio files are produced in a batch process and the image files and thumbnails are moved over to the downtown server. Each jukebox selection now has a folder on the server that contains the corresponding audio files and label images of that selection.