A coaxial loudspeaker is a
loudspeaker
A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or " ...
system in which the individual driver units radiate sound from the same point or axis. Two general types exist: one is a compact design using two or three
speaker driver
An electrodynamic speaker driver, often called simply a speaker driver when the type is implicit, is an individual transducer that converts an electrical audio signal to sound waves. While the term is sometimes used interchangeably with the ...
s, usually in
car audio
Vehicle audio is equipment installed in a car or other vehicle to provide in-car entertainment and information for the vehicle occupants. Until the 1950s it consisted of a simple AM radio. Additions since then have included FM radio (1952), 8 ...
, and the other is a two-way high-power design for
professional audio
Professional audio, abbreviated as pro audio, refers to both an activity and a category of high quality, studio-grade audio equipment. Typically it encompasses sound recording, sound reinforcement system setup and audio mixing, and studio mus ...
, also known as single-source or dual-concentric loudspeakers. The design is favored for its compactness and behavior as an
audio point source.
Professional audio
![MCI equipped Studiod](https://upload.wikimedia.org/wikipedia/commons/a/af/MCI_equipped_Studiod.jpg)
Coaxial loudspeakers in professional audio enable sound from two drivers to come from one source. This characteristic allows a wider field of listening to a synchronized summation of speaker drivers than
loudspeaker enclosure
A loudspeaker enclosure or loudspeaker cabinet is an enclosure (often rectangular box-shaped) in which speaker drivers (e.g., loudspeakers and tweeters) and associated electronic hardware, such as crossover circuits and, in some cases, power ...
s containing physically separated drivers. As well, the pattern of response is symmetric around the axis of the loudspeaker.
Since the 1943 introduction of the
Altec Lansing Duplex 601 coaxial driver, recording
studio monitor
Studio monitors are loudspeakers in speaker enclosures specifically designed for professional audio production applications, such as recording studios, filmmaking, television studios, radio studios and project or home studios, where accurate ...
s have often been coaxial loudspeaker designs. In 1945 the improved Altec 604 was introduced, and it soon became the recording industry standard studio monitor in the U.S. First shown in 1947 in England, the
Tannoy
Tannoy is a British manufacturer of loudspeakers and public address systems. Founded by Guy Fountain in London in 1926 as the Tulsemere Manufacturing Company, today the company is part of the Music Tribe group of brands.
History
Tannoy Ltd is ...
Dual Concentric design assumed the same role across Europe from the 1950s onward. The Altec 604 combined a woofer with a
compression driver
A compression driver is a small specialized diaphragm loudspeaker which generates the sound in a horn loudspeaker. It is attached to an acoustic horn, a widening duct which serves to radiate the sound efficiently into the air. It works in a "co ...
attached to a
horn
Horn most often refers to:
*Horn (acoustic), a conical or bell shaped aperture used to guide sound
** Horn (instrument), collective name for tube-shaped wind musical instruments
*Horn (anatomy), a pointed, bony projection on the head of various ...
to carry the high frequencies. The Tannoy also used a 15-inch woofer and a compression driver for high frequencies, but differed in that the woofer itself served as the final horn flare for the high frequency driver.
Thus, its output pattern was radially symmetric, not just mirror-image symmetric as in the Altec. Both designs placed the high frequency driver ''behind'' the low frequency driver, and both were not initially time aligned. The high frequencies arrived at the listener's ear slightly later than the low frequencies.
One drawback of the design is the production line difficulty in mating the two drivers, and in replacing or reconing the woofer. Another drawback is that the low frequencies tend to modulate the high frequencies, causing greater
intermodulation distortion
Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency com ...
. The Tannoy style of coaxial, with the woofer forming part of the high frequency horn, had greater intermodulation distortion. Designs similar to the Altec 604 have further problems with diffraction of the low frequencies around the central horn, and with rearward emanations from the horn body reflected forward by the woofer out of time with direct sound. All of the problems with sound waves tend to increase with
sound pressure
Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone ...
level, causing significant shifts in tone as the loudspeaker changes volume.
In the late 1970s,
Bill Putnam
Milton Tasker "Bill" Putnam (February 20, 1920 – April 13, 1989) was an American audio engineer, songwriter, producer, studio designer and businessman, who has been described as "the father of modern recording". He was the inventor of the mo ...
of
Universal Audio
United Recording Electronics Industries (UREI) was a manufacturer of recording, mixing and audio signal processing hardware for the professional recording studio, live sound and broadcasting fields.
History
Bill Putnam Sr. founded Universa ...
worked with
Ed Long and his patented Time Alignment crossover design to fix the long-standing problem of the two bandpasses not being aligned in time at their crossover point. The Altec 604 was given this elaborate new crossover feature and incorporated into the UREI 813 studio monitor, which also had a second woofer physically separate from the coaxial pair. This design dominated recording studios of the 1980s, and time alignment became a feature of competing manufacturers.
[ In 1977, Bob Cavin of McCune Sound in ]San Francisco
San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
modified the Altec 604 for the McCune SM-4, a large proprietary stage wedge, using John Meyer's patented high-compliance compression driver diaphragm, a higher-power woofer, and processor-controlled bi-amplification with line-level all-pass time alignment. The McCune SM-4 was the first multi-angle stage monitor
A stage monitor system is a set of performer-facing loudspeakers called monitor speakers, stage monitors, floor monitors, wedges, or foldbacks on stage during live music performances in which a sound reinforcement system is used to amplify a p ...
, and was used by many McCune clients such as the Playboy Jazz Festival
The Hollywood Bowl Jazz Festival is an event held in the Hollywood Bowl that celebrates jazz and features both established and up-and-coming jazz musicians. Founded in 1959 by Hugh Hefner as the Playboy Jazz Festival, it was held in Chicago but d ...
and the Monterey Jazz Festival
The Monterey Jazz Festival is an annual music festival that takes place in Monterey, California, United States. It debuted on October 3, 1958, championed by Dave Brubeck and co-founded by jazz and popular music critic Ralph J. Gleason and jaz ...
. In the 2000s, digital signal processing
Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are ...
(DSP) was used by Fulcrum Acoustic to reduce some of the coaxial drawbacks such the diffraction of the woofer's upper range around the central horn, by filling in this "shadow" with low frequency sound from the compression driver, and by countering the out-of-time reflections bouncing off of the woofer.[
Coaxial loudspeakers have been used in ]stage monitor
A stage monitor system is a set of performer-facing loudspeakers called monitor speakers, stage monitors, floor monitors, wedges, or foldbacks on stage during live music performances in which a sound reinforcement system is used to amplify a p ...
s, giving musicians a more even sound field because of the single-source characteristic. As well, the enclosure may be made more compact. In the 1980s, Professional Audio Systems (PAS), using Time Alignment technology from Ed Long, sold the popular SW series of compact stage wedges, offered with a 12- or 15-inch woofer, and having a projecting high-frequency horn as in the 604. Other stage monitors using coaxial designs are made by Clair Brothers, L-Acoustics
L-Acoustics is a French manufacturer of loudspeakers, amplifiers, marketing materials, and signal processing devices for rental and installed sound markets. Headquartered in Marcoussis, south of Paris, the company has offices in the United State ...
, Radian Audio Engineering, RCF, Beyma, dB Technologies, Fulcrum Acoustic, and Rat Sound Rat Sound Systems is a sound equipment provider of touring sound reinforcement equipment and services to the concert touring industry, based in Camarillo, California.
Rat Sound Systems was established in 1980 by Dave Rat and Brian Benjamin, and is ...
in partnership with Eastern Acoustic Works
Eastern Acoustic Works (EAW) is an American manufacturer of mainly professional audio reinforcement tools, such as loudspeaker systems and processors.
From 1978-1988 it was located at 59 Fountain Street in Framingham, Massachusetts, and subsequent ...
.
David Gunness
David W. Gunness (born November 7, 1960) is an American audio engineer, electrical engineer and inventor. He is known for his work on loudspeaker design, especially high-output professional horn loudspeakers for public address, studio, theat ...
and Fulcrum Acoustic have designed coaxial loudspeakers beginning in 2009, notably collaborating with PreSonus
PreSonus Audio Electronics, Inc. (often known and styled as PreSonus) is an American manufacturer of professional audio equipment and software, used to create, record, Audio mixing, mix, and Audio mastering, master music and other audio. This inc ...
in 2013 to create the self-powered line of Sceptre S6 and S8 coaxial studio monitors, and releasing Fulcrum's own FH15 full-range horn-loaded loudspeaker series in 2018. All of the coaxial Fulcrum designs use digital signal processing to reduce distortion modes. Fulcrum's proprietary process is called Temporal Equalization (TQ).
Home audio
Tannoy
Tannoy is a British manufacturer of loudspeakers and public address systems. Founded by Guy Fountain in London in 1926 as the Tulsemere Manufacturing Company, today the company is part of the Music Tribe group of brands.
History
Tannoy Ltd is ...
has produced coaxial loudspeakers, for the hi fidelity home consumer market since the early 1950s. Their "Dual Concentric" drivers early series included in order of introduction: Tannoy Blacks, Tannoy Silvers, Tannoy Reds, and Tannoy Golds. Jensen introduced several coaxial speakers in the 1950s including their highly regarded triaxial models. Several other manufacturers introduced coaxial speakers and drivers in the 1950s including University, however due to their higher cost most did not last in the consumer market.
In 1988, KEF
Kef may refer to:
Places
* El Kef (also transliterated as ''Al-Kāf'' or ''Le Kef''), a city in northwestern Tunisia
*Kef Governorate, Tunisia
Others
*''Aram Bajakian's Kef'', a 2011 album by guitarist Aram Bajakian
* ISO 639:kef or Ewe languag ...
introduced an extension of the coaxial loudspeaker concept. Their Uni-Q driver is a coincident driver, where the two drivers share the same acoustic center and therefore are closer in time alignment. This was made possible by using the then newly affordable powerful yet small neodymium magnets for the tweeter making the whole tweeter assembly small enough, magnet included, to fit inside the woofer's voice coil. Other home audio speaker companies making coaxial speakers include TAD, Cabasse with their 4-way Concentric QC-55 Driver as seen in their flagship model - La Sphère, Hsu, Vandersteen, until recently Theil, and a budget speaker made a few years ago by Insignia.
Car audio
Coaxial speakers in automobiles are 2- or 3-way loudspeakers in which the tweeter
A tweeter or treble speaker is a special type of loudspeaker (usually dome, inverse dome or horn-type) that is designed to produce high audio frequencies, typically deliver high frequencies up to 100 kHz. The name is derived from the high ...
, or the tweeter and a mid-range driver, are mounted in front of the woofer
A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency sounds, typically from 50 Hz up to 1000 Hz. The name is from the onomatopoeic English word for a dog's bark, " woof" (in contrast to th ...
, partially obscuring it. The advantage of this design is the ability to use a smaller area, hence their popularity in car audio. The low frequency sound waves from the woofer are not reduced too much by the drivers in their path. Without time-alignment correction, the sound from the tweeter may arrive slightly before the sound from the woofer; this misalignment is not generally addressed in automobile sound systems.
This design was popularized in the 1970s with Electronic Industries, Inc. of South Holland, Illinois
South Holland is a village and south suburb of Chicago in Cook County, Illinois, United States, within Thornton Township. The population was 21,465 at the 2020 census.
History
The area currently occupied by South Holland, Illinois, was first ...
introducing the general concept in May 1973, and Jensen Loudspeakers Jensen Loudspeakers is a company that manufactures speakers in many different models and sizes. Originally located in Chicago, Illinois, the company built a reputation during the 50s and 60s providing speakers used mainly in guitar and bass amplifie ...
introducing a retail model the next month. This was followed by designs from Sparkomatic, Clarion
Clarion may refer to:
Music
* Clarion (instrument), a type of trumpet used in the Middle Ages
* The register of a clarinet that ranges from B4 to C6
* A trumpet organ stop that usually plays an octave above unison pitch
* "Clarion" (song), a 2 ...
, Infinity
Infinity is that which is boundless, endless, or larger than any natural number. It is often denoted by the infinity symbol .
Since the time of the ancient Greeks, the philosophical nature of infinity was the subject of many discussions amo ...
and others.
References
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Loudspeaker technology