RCA Photophone was the trade name given to one of four major competing technologies that emerged in the American film industry in the late 1920s for synchronizing electrically recorded audio to a motion picture image. RCA Photophone was an optical sound, "variable-area" film exposure system, in which the modulated area (width) corresponded to the waveform of the audio signal. The three other major technologies were the Warner Bros. Vitaphone sound-on-disc system, as well as two "variable-density" sound-on-film systems, Lee De Forest's Phonofilm, and Fox-Case's Movietone.
When Joseph P. Kennedy and other investors merged Film Booking Offices of America (FBO) with the Keith-Albee-Orpheum theater chain and Radio Corporation of America, the resulting movie studio RKO Radio Pictures used RCA Photophone as their primary sound system. In May 1929, RKO released, the first film made in RCA Photophone.
History and licensing
In the early years following World War I, Charles A. Hoxie working at General Electric (GE) developed a photographic film recorder, initially to record transoceanic wireless telegraphy signals. However this recorder was later adapted for recording speech and was used in 1921 to record speeches by President Coolidge and others which were broadcast over Station WGY (Schenectady). This recorder was called the .
In 1925 GE started a program to develop commercial sound-on-film equipment based on Hoxie's work. Unlike the Phonofilm and Movietone systems in which the audio modulated the intensity of a recording lamp which exposed the soundtrack, thus creating a variable-density track, the GE system employed a fast-acting mirror galvanometer to create a variable-area soundtrack. A number of demonstrations of this system, now known as Photophone, were given in 1926 and 1927. The first public screenings with this system were of a sound version (music plus sound effects only) of the silent film Wings which was exhibited as a road-show in around a dozen specially equipped theatres during 1927.
In 1928 RCA Photophone Inc was created as a subsidiary of RCA (itself then a GE subsidiary) to commercially exploit the Photophone system. The RCA system continued to use the galvanometer until the 1970s, when it became technically obsolete. The Western Electric system continued to use the light valve, and, under successor ownership, is still used to this day.
For nearly half a century, motion picture sound systems were licensed, with two major licensors in North America, RCA and Western Electric (Northern Electric, in Canada), which licensed their principal sound element (original track negative) recording systems on a non-exclusive basis. In general, motion picture producers elected to license one or the other. In a few cases, where mergers had occurred, a producer might be licensed for both. For many years, it was customary to "brand" a film with its sound system, variously as "RCA Sound Recording", "Western Electric Recording", or similar brands, often including the corporate logo of the licensor (Meatball for RCA; The Voice of Action for Western Electric; Li Westrex for the post-1956 divestiture of Western Electric under Litton Industries' ownership). Such branding ceased in about 1976, particularly after nearly all optical sound recording (for release prints) had been converted to Westrex's stereo variable-area system from RCA's and Westrex's mono systems, although there were a few examples of such branding thereafter (mainly Westrex.)
Many years later, the Photophone trademark would be reused by the Western Electric/Westrex stereo variable-area system, after both the Western Electric and Westrex trademarks became unavailable due to corporate asset sales by the disintegrating Bell System, but the Western Electric/Westrex stereo variable-area system continued to be marketed by a successor, and it is still serviced and supported to this day, although it is no longer branded as Photophone.
List of licensees
Primary (major producer) RCA (Photophone) licensees include:
Comparison of (mono) variable-area and variable-density
Although variable-density sound system recording is usually associated with Western Electric and variable-area sound system recording is usually associated with RCA, these relationships are not cast into stone.
Both variable-area systems and variable-density systems were marketed by both RCA and Western Electric, the Western Electric light valve being capable of producing either variable-density or variable-area depending on which ribbon axis was parallel to the film motion, and the RCA galvanometer was capable of producing either variable-area or variable-density depending upon the particulars of the optical system.
Roughly equal measured and perceived quality was available from both systems and from both manufacturers. Neither recording system nor manufacturer was clearly superior to the other, except where specific customer end-to-end processes made one system/manufacturer more consistently superior to the other system/manufacturer.
Variable-density was preferred for Technicolor sound prints as this process utilized a silver gray-scale "key" record, thereby creating a CMYK color image, and the sound track was also a silver gray-scale record, which greatly facilitated variable-density (and made variable-area rather difficult). The "key" record was deleted from most Technicolor prints after 1944, thereby creating a CMY color image, but Technicolor's strong preference for variable-density continued long thereafter.
Variable-density was finally abandoned as customer preferences for "dual-bilateral" variable-area sound tracks emerged in the late 1950s. This required changes to some laboratory processing and quality controls, but the real reason for variable-density's demise was yet to come.
In the early-1970s there was renewed interest in improving the quality of optical film soundtracks.
As a consequence by the early 1970s several individuals and organizations were considering improvements to the dated technical standards used for optical sound on 35mm film. In particular both Dolby Labs and Kodak were investigating the use of Dolby noise reduction on optical soundtracks.
In the mid-1970s Westrex Corp. (a wholly owned subsidiary of Litton Industries since 1956, and the successor to Western Electric's cinema sound business unit) re-introduced the ca. 1938 "four ribbon" light valve, and the ca. 1947 RA-1231 sound recorder.