4. Playing back audio media The recordings you want to digitise may reside on just one type of analogue medium, or may use several different media. If all the sound is on one medium, this makes the digitisation task much easier as only one type of playback machine is needed. Some analogue recording media are easier to deal with than others. Old and obsolete media such as phonograph cylinders or gramophone disks will require appropriate historical equipment for playback, and the media themselves may be extremely delicate. They will need to be acoustically recorded, and this would normally need to be done in a recording studio. Other media, such as LP records and cassette tapes, use readily available playback equipment which can be connected to the computer for digitisation. This chapter does not give information on how to connect and set up playback equipment. This information can be found in section 7.1. What follows is a brief discussion of a variety of media, organised roughly chronologically. 4.1. Early sound recording media Sound recording began in 1877 with Thomas Edison's invention of the phonograph, a machine which used a tinfoil coated cylinder to record movements of a needle connected to a diaphragm which vibrated in sympathy with sound waves. The phonograph developed through the following few decades with the introduction of wax cylinders, electric drive motors, and methods of mass production of cylinders. Following Emile Berliner's invention of the gramophone in 1887, the competing formats of cylinder and lateral disk developed in parallel. However, Berliner was the first to develop a way of mass producing recordings, making hard rubber disks from zinc masters. In 1913, Edison finally conceded victory to the flat disk when his company stopped making cylinders and began to produce 'Diamond Disc' phonographs and recordings. For detailed information on cylinder phonographs and gramophone technology, as well as guidance about playing and handling media and players, a useful website can be found at http://www.tinfoil.com. 4.1.1. The cylinder phonograph Edison's initial cylinders were coated with tinfoil and played for 2-3 minutes. In 1885, Tainter and Bell invented another machine, called the graphophone, which used wax coated cylinders. Over the following years various methods for producing cylinders were tried, and various materials were used, such as hard wax and celluloid. In 1902, speeds were standardised to 160 rpm, and by 1908 the groove density of cylinders had doubled allowing a 4 minute playing time. A digitisation project requiring the playback of cylinders will require specialist knowledge and an appropriate phonograph machine. The cylinders will be highly delicate and will need very careful handling. It may be that playing the cylinders would destroy them, so this specialist knowledge is vital. The phonograph will need to be recorded acoustically using a microphone - the mechanical signal from the machine needs to be converted into an electrical signal before it can be digitally captured. This would be best achieved in a recording studio with appropriate space and equipment. 4.1.2. The gramophone Berliner's gramophone disks were 7 inches in diameter, played at a speed of 30 rpm and had a duration of 2 minutes. As with the phonograph, the years immediately following its inception were filled with experimentation and development. A variety of materials and formats were tried: the initial disks were vulcanite rubber, replaced in 1897 with shellac; a 10-inch format with 4 minute playing time replaced the 7 inch format; double-sided disks were developed; and in 1925, with the advent of electrical recording, the speed was standardised to 78 rpm. Prior to this various recording speeds had been used, and players had adjustable speed. Shortly after the first electrically recorded disks went on sale in 1925, a 16-inch acetate-coated shellac disk format with a speed of 33 1/3 rpm was used to synchronise sound to film. As with cylinders, successful playback of gramophone records requires some specialist knowledge. The sound quality will improve with cleaning the disks and having the correct kind of playback equipment. This will also help to avoid damaging the disks or degrading them further. It is vital that cleaning or repairing disks should only be attempted with appropriate knowledge and equipment. Again, there are useful links at http://www.tinfoil.com. As with the phonograph, the gramophone will need to be recorded acoustically. This would be best achieved in a recording studio with appropriate space and equipment.
Top of Page
| 
Page last modified: by