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Loudspeaker History
1874 - Ernst W. Siemens was the first to describe the "dynamic" or
moving-coil transducer, with a circular coil of wire in a magnetic field and
supported so that it could move axially. He filed his U. S. patent application
for a "magneto-electric apparatus" for "obtaining the mechanical movement of an
electrical coil from electrical currents transmitted through it" on Jan. 20,
1874, and was granted patent No. 149,797 Apr. 14, 1874. However, he did not use
his device for audible transmission, as did Alexander G. Bell who patented the
telephone in 1876. After Bell's patent was granted, Siemens applied for German
patent No. 2355, filed Dec. 14, 1877, for a nonmagnetic parchment diaphragm as
the sound radiator of a moving-coil transducer. The diaphragm could take the
form of a cone, with an exponentially flaring "morning glory" trumpet form. This
is the first patent for the loudspeaker horn that would be used on most
phonographs players in the acoustic era. His German patent was granted July 30,
1878 and his British patent No. 4685 was granted Feb. 1, 1878.
1898 - Oliver Lodge
filed for British patent No. 9712 on Apr. 27, 1898, for an improved loudspeaker
with nonmagnetic spacers to keep the air gap between the inner and outer poles
of a moving coil transducer. This was the same year he applied for a patent on
his famous radio tuner. A model of his loudspeaker is in the British Science
Museum in South Kensington, and a photo was published in Wireless World
Dec. 21, 1927. This improvement was later claimed by Pridham and Jensen in the
Magnavox application for patent No. 1,448,279 filed Apr. 28, 1920, and granted
Mar. 13, 1923.
1901 - John Stroh first described the conical paper diaphragm that terminated
at the rim of the speaker in a section that was flat except for corrugations,
filed for the British patent No. 3393 on Feb. 16, 1901, granted Dec. 14, 1901.
1908 - Anton Pollak improved the moving-coil loudspeaker with a voice-coil
centering spider, filed for U.S. patent No. 939,625 on Aug. 7, 1908, granted
Nov. 9, 1909.
1911 - Edwin S. Pridham and Peter L. Jensen in
Napa, California, invented a moving-coil loudspeaker they called the "Magnavox"
that was used by Woodrow Wilson in San Diego in 1919.
early Bell
loudspeakers | 1915 - Harold Arnold began
program at Bell Labs to improve phonographic sound recording. The first priority
was the electronic amplifier using the new vacuum tube, second was the
microphone, and third was the loudspeaker that would improve the "balanced
armature" units developed for public address. After WWI, J. P. Maxfield led this
project that produced E. C. Wente's moving coil speaker by 1925, the Orthophonic
phonographic player by 1925, and Vitaphone talking motion pictures by 1926.
1918 - Henry Egerton on 1918/01/08 filed patent for balanced-armature
loudspeaker, used in the Bell Labs No. 540AW speakers developed by N. H. Ricker
Oct. 6, 1922, that became the 540 commercial speaker by 1924; was based on the
balanced armature telephone patent of Thomas Watson granted Oct. 24, 1882,
similar to devices also developed by Siemens and Frank Capps.
1925 Grebe radio receiver and 1924 Western
Electric 540 speaker (NMAH) |
1921 - The Phonetron based on patent No.
1,847,935 filed Apr. 23, 1921, by C. L. Farrand, was the first coil-driven
direct-radiator loudspeaker to be sold in the U.S. and was well-received,
competing with the horns used by table radios
1923 - The Thorophone was a gooseneck
loudspeaker with a voice-coil driver
1925 - The research paper of Chester W. Rice
and Edward W. Kellogg at General Electric was important in establishing the
basic principle of the direct-radiator loudspeaker with a small coil-driven
mass-controlled diaphragm in a baffle with a broad midfrequency range of uniform
response. Edward Wente at Bell Labs had independently discovered this same
principle, filed patent No. 1,812,389 Apr. 1, 1925, granted June 30, 1931. The
Rice-Kellogg paper also published an amplifier design that was important in
boosting the power transmitted to loudspeakers. In 1926, RCA used this design in
the Radiola line of a.c. powered radios.
1925 - Victor Orthophonic acoustic phonograph player
had a folded exponential horn that was later used as model for the Klipsch
speaker of the hi-fi era. Within a year, the Orthophonic faced competition from
all-electric phonographs with an electromechanical pickup, vacuum-tube
amplifier, and moving-coil loudspeaker, such as the Brunswick Panatrope sold by
the Brunswick-Balke-Collender Company.
Vitaphone 555-W, from AT&T
Archives | 1926 - Vitaphone sound system
for motion pictures used a new speaker developed at Bell Labs. Wente and Thuras
designed the Western Electric 555-W speaker driver that was coupled with a horn
having a 1-in. throat and a 40-sq. ft. mouth; it was capable of 100-5000 hz
freq. range with an efficiency of 25% (compared to 1% today) needed due to low
amp power of 10 watts. The power amps were 205-D. Older loudspeakers were
balanced armature type, but the newer 555-W speakers of the Vitaphone were
moving coil type.
1928 - Herman J. Fanger filed patent No. 1,895,071 on Sep. 25, 1928, granted
Jan. 24, 1933, that described what came to be known as the coaxial speaker,
composed of a small high frequency horn with its own diaphragm nested inside or
in front of a large cone loudspeaker, based on the variable-area principle that
made the center cone light and stiff for high frequencies and the outer cone
flexible and highly damped for lower frequencies.
1929 - E. W. Kellogg filed patent No. 1,983,377 on September 17, 1929,
granted December 4, 1934, that described an electrostatic speaker composed of
many small sections able to radiate sound with out magnets or cones or baffles.
This patent, as well as the 1932 British patents of Hans Vogt, influenced Peter
Walker to build the Quad ESL flat panel speaker in 1957.
1929 - J. D. Seabert of Westinghouse developed a horn-type loudspeaker that
directed the sounds of human speech toward the audience better than cone
speakers that were intended for the over-all sound including music to fill the
entire theater. These "directional baffle" horns had an opening 3 ft. by 4 ft.
and were different from small-throat horns.
Thuras bass-reflex
patent |
1930 - Albert L. Thuras filed patent No. 1,869,178 on Aug. 15, 1930, granted
July 26, 1932, for the bass-reflex principle while working at Bell Labs. Early
cabinets used a passive baffle to direct sound to the front, allowing the back
of the cabinet to be open for the low sounds. The bass-reflex enclosure kept the
low-frequency sounds from being lost from the rear of the diaphragm.
1931 - Bell Labs developed the two-way loudspeaker, called "divided range"
for the demonstration by H. A. Frederick in December of vertically cut records.
The high frequencies were reproduced by a small horn with a frequency response
of 3000-13,000 hz, and the low frequencies by a 12-inch dynamic cone
direct-radiator unit with a frequency response within 5db from 50-10,000 hz. By
1933, a triple-range speaker had been developed for the Constitution Hall demo
in April, adding Western Electric No. 555 driver units as the mid-range speaker.
For the low frequency range 40-300 hz, a large moving coil-driven cone diaphragm
in a large baffle expanding from a 12-in throat to a 60-inch mouth over a total
length of 10 ft. This 3-way system was introduced in motion picture theaters as
"Wide Range" reproduction.
1932 - RCA demonstrated a dual-range speaker of its own design for theaters,
using three 6-inch cone diaphragms with aluminum voice coils in divergent
directions, with a response of 125-8000 hz, and 10-ft. horns 40-125 hz.
1933 - "Progress was such that a demonstration of the new system - called
"stereophonic" because of its ability to give a spatial sense corresponding to
stereoscopic vision - was given before the National Academy of Sciences and many
invited guests at Constitution Hall, Washington in the spring of 1933.
Transmission was
Thuras theater speaker 1933, from AT&T
Archives | over wire lines from the
Academy of Music in Philadelphia and three channels were used with microphones
respectively at left, center and right of the orchestra stage and loud speakers
in similar positions in Constitution Hall." This transmission of music "was
carried out with special loud speakers developed for the purpose by Dr. Wente
and the late A. L. Thuras. The objectives in the design of these loudspeakers
were uniform response over the whole tonal range of the orchestra, an enhanced
sound power output capacity without noticeable non-linear distortion and uniform
distribution of the emitted sound at all frequencies throughout a wide solid
angle. For the receiving unit and the multicellular horn which were developed
for this demonstration, Dr. Wente, jointly with the Bell Telephone Laboratories,
was awarded a gold plaque by the Academy of Motion Picture Arts and Sciences in
1936." (Bell Labs, 1953)
1935 - Douglas Shearer and John Hilliard at MGM developed a standard theater
speaker system, starting with the Loews 5000-seat Capitol Theater on Broadway.
James Lansing and Dr. John F. Blackburn of Cal Tech designed a 2-way speaker
system; the high frequency driver had a 3-inch aluminum diaphragm and throat
size of 1.4 inches; the low frequency baffled cone unit was 15 inches. ERPI
provided speakers from Fletcher's hi-fi experimental equipment to help design
the speakers. The low frequency horn used four 15-in. Lansing cone drivers and
Lansing 284 drivers for multicell horns of different sizes. The system was
installed in 12 theaters for the opening of "Romeo and Juliet" with Norma
Shearer, sister of Douglas,
Altec A-7 Voice of the Theatre, from
Audio, Dec. 1961 | then installed
in all Loews Theaters, then became the standard established by the Academy.
1940 - Paul W. Klipsch filed patent No. 2,310,243 on Feb. 5, 1940, granted
Feb. 9, 1943, for the corner horn speaker.
1941 - Altec Lansing Corp. was formed when Altec bought Lansing; Altec
Service Corp. (from "all technical") had been formed in 1938 by M. Conroe and
George Carrington to manage ERPI installations after ERPI was dissolved. John
Hilliard worked at Altec Lansing in 1943 on magnetic airborne sub detection and
in 1945 put on the market the 2-way "Voice of the Theater" speaker system with
improved horns and magnet drivers. See Lansing Heritage for images and a
detailed history.
Avery Fisher with 9-tube amp and coaxial
speaker, from Fortune, Oct.
1946 | 1949 - W. E. Kock and F. K. Harvey
at Bell Labs developed the acoustical lens, and reported findings in 1949 JAES.
These lenses are used in James B. Lansing theater speakers and home hi-fi
speakers
1953 - Arthur Janszen was granted patent No. 2,631,196 on March 10, 1953, for
an electrostatic high-frequency speaker
1954 - Acoustic Research introduced the small AR-1 bookshelf loudspeaker that
used the acoustic suspension principle developed by company co-founder Edgar Villchur. This was soon followed by the $89 AR-2
and by the AR-3 with improved domed tweeters in 1958.
Walker's ESL, from Quad | 1957
- Quad ESL marketed as the first full-range electrostatic loudspeaker, designed
by Peter Walker and David Williamson, based on Edward W. Kellogg's patent No.
1,983,377 filed September 17, 1929 and granted December 4, 1934.
1974 - Earthquake premiered Nov. 15 in the Chinese Theater in
Hollywood with Universal Picture's Sensurround process developed by W. O. Watson
and Richard Stumpf at Universal. Four large low-frequency horns were located
behind the screen, two in each corner. The Model W horn in each corner was 8 ft.
long, 4 ft. wide, 4 ft. high. The Model C horn in each corner was a modular unit
1 ft. wide and 5 ft. high. Two additional horns were located on a platform in
the rear of the theater. Each horn was driven by a 1000-watt amplifier
controlled by inaudible tones on a special optical control track along with the
normal 4-track magnetic soundtrack of the 35mm Panavision filmstrip.
1982 - Return of the Jedi was the first movie exhibited on the THX
sound system designed by George Lucas and Tomlinson Holman; THX "is comprised of
customized acoustical design work for each auditorium, a
special screen speaker
installation method, a proprietary electronic crossover network, and rigorous
audio equipment specifications and performance standards."
1996 - The Verity Group in Britain formed New Transducers Ltd, now known as
the NXT company , to develop the
Distributed-Mode Loudspeaker (DML) based on the 1991 patent by Dr Ken Heron of
Britain's Defence Evaluation & Research Agency (DERA)
1998 - Benwin marketed the first DML flat panel loudspeakers
Sources:
- Augspurger, George L. "Theory, Ingenuity, and Wizadry in Speaker Design,"
Audio, April 1987 p. 51-55, originally published in Journal of the
Acoustical Society of America 77, No. 4, April 1985, p. 1303-1308, describes
five milestone loudspeaker designs over the last 50 years: Rice-Kellogg 1925,
Altec Lansing Model 604 duplex 1943, Klipsch corner horn 1946, Jensen bass
reflex in the 1940s that was an early version of the vented box enclosure
defined by Thiele-Small 1961, and Villchur acoustic
suspension 1954.
- Douglas, Alan. Radio Manufacturers of the 1920's. Vestal Press
Ltd, 1989.
- Hunt, Frederick V. Electroacoustics: the Analysis of Transduction, and
its Historical Background. New York: American Institute of Physics for
the Acoustical Society of America, 1982.
- Olson, Harry Ferdinand. Acoustical Engineering. Princeton,
N.J.: Van Nostrand,1957.
- Rice, Chester W. and Edward W. Kellogg, "Notes on the Development of a New
Type of Hornless Loudspeaker," Transactions of the American Institute of
Electrical Engineers 44, 1925, p. 461-475.
- "Edward C. Wente" biography manuscript, Bell Telephone Laboratories, Sept.
17, 1953, Box 228-07-01, AT&T Archives, Warren, NJ.
- Rice, Chester W. and Edward W. Kellogg, "Notes on the Development of a New
Type of Hornless Loudspeaker," Transactions of the American Institute of
Electrical Engineers 44, 1925, p. 461-475.
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