152:, "An audio power amplifier is required to produce an output signal that differs from the input signal in magnitude only. It must therefore have occurred to every circuit designer that it should be a simple matter to take a portion of the output, compare it with the input to derive an error signal. It is then only necessary to amplify the error signal and add it to the output in the correct amplitude and phase to cancel completely the distortion of the primary amplifier."
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original audio input and derive the required error correction signal which is then injected into the audio path, in such a way that the high power audio output achieves a very low distortion figure, even at very high power levels. This innovative product earned Quad the Queen's Award for
Technological Achievement in 1978.
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Quad launched ESL-63, successor to the original ESL, in 1981. The newer design featured larger panels and an innovative stator design, made up of eight concentric rings fed from the centre outwards through analogue delay lines, so that the audio signal radiated out as though emanating from a single
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renowned for sonic transparency and very low distortion. Its sonic neutrality and transparency were offset by its extreme directionality, moderate power handling, the need for a large room, and moderate bass extension; its novel electrical characteristics could render some amplifiers unstable, which
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Walker put this principle into practice using two amplifiers per channel instead of one. The first stage error amplifier is low powered but very high quality. The second amplifier is high powered, but of lesser audio high quality. Walker designed a way to compare the high powered output with the
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In late 1949 (or early 1950), the company launched the CR corner ribbon loudspeaker. This used a
Goodmans Axiom 150 cone loudspeaker for the lower frequencies and an electromagnetic ribbon loudspeaker, designed by Acoustical, for the higher frequencies. Fewer than one thousand units were sold.
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Following the mass production of 'stereo' vinyl records in 1958, the QC 22 control unit was developed and released in 1959. This was a stereo control unit that was designed to be used with a pair of QUAD II mono power amplifiers. To complement the QUAD II, the company also produced
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point. Subsequent electrostatic models, the 988/989, the 2805/2905 and then the 2812/2912 were successive refinements of the ESL-63 design, featuring increased power handling and output levels, more sophisticated overload protection, and greater structural rigidity.
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Walker was also attributed with the famous hifi quote "the perfect amplifier is a straight wire with gain" with the implication being that nothing would be added, and nothing taken away from the signal, just a bigger version of the same thing at one end.
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The company made the transition to transistor-powered models in 1966 with the "professional" QUAD 50 monobloc which had a tapped transformer output, and in 1967 the consumer Quad 33 preamplifier and 303 stereo power amplifier combination.
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Following the Verity acquisition, Quad developed and market a range of conventional electrodynamic loudspeakers alongside its electrostatic line, available in both passive and active (i.e. featuring in-box amplification) configurations.
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The ESL was quickly adopted by the BBC for monitoring the sound quality of their broadcasts. The BBC eventually replaced them with moving coil based monitor speakers developed by several manufacturers, such as the highly successful
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In
September 1997 the company changed ownership again as Verity Group sold off businesses to finance its development of flat panel loudspeakers. With Wharfedale it became part of the Chinese
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The name "QUAD" is an acronym for "Quality Unit
Amplifier Domestic", used to describe the QUAD I amplifier. In 1983, when having become known for their QUAD range of products, the
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244:. This valve power amplifier featured a cathode-coupled winding dating from 1943, which eventually became the Quad II. The QII preamplifier accompanied it.
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Many of Quad's products, including the Quad
Electrostatic Loudspeaker (ESL-57), are still serviced by the company's Service Department in Huntingdon.
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designs. This unit's sound quality reproduction was high compared with other products on the market at the time, and was thus adopted for use by the
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equipment but after the war they began to produce equipment designed for use in the home as a result of the rising demand for high quality domestic
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In 2003, a book was commissioned "QUAD:The
Closest Approach" which offered a history of the company from its creation to that point.
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Peter Walker died in 2003 at the age of 87. He had retired in the late 1980s, turning management over to his son Ross Walker.
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equipment, based
Huntingdon, England. QUAD is part of the IAG Group, with corporate headquarters located in Shenzhen, China.
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The company's first major products were released in 1948. The QA12 and QA12/P were low-powered mono
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U112 combined integrated mono valve PA amplifier and mixer with 3 microphone inputs - 1945+
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130:. The company moved from London to Huntingdon in 1941 after being bombed out of London in
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The company was founded by Peter J. Walker in 1936 in London, and was initially called
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https://web.archive.org/web/20150228214406/http://www.iaggroup.com/WHARFEDLE.html
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https://web.archive.org/web/20150811030914/http://www.iaggroup.com/quad1.html
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and
Mission. A few changes were made, including shifting all production to
642:. Huntingdon, Cambridge, UK: International Audio Group Ltd. p. 183.
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A Quad L-ite satellite speaker provides the audio for a concert at home.
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U113 combined integrated mono valve PA amplifier and radio tuner - 1945+
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Home entertainment equipment manufacturing & distribution
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526:(1st ed.). Devon, UK: Sunrise Press. pp. 92–93.
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Quad FM Multiplex decoder - 1965 to 1967 - 5,000 units
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Quad QCII Control Unit - 1953 to 1959 - 20,000 units
196:under the management of Bernard and Michael Chang.
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Audio equipment manufacturers of the United
Kingdom
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296:Quad 22 Control Unit - 1959 to 1967 - 30,000 units
462:(ESL), the first production full frequency range
292:Quad QC1 Control Unit - 1951 to 1953 - 2000 units
174:In 1995, QUAD Electroacoustics Ltd was bought by
280:for use with the QC II & 22 control units.
218:MB32 integrated mono valve PA amplifier - 1947+
214:MB31 integrated mono valve PA amplifier - 1946+
511:CHINA: Behind the scenes at IAG | whathifi.com
222:M18 integrated mono valve PA amplifier - 1952+
220:M60 integrated mono valve PA amplifier - 1947+
216:M32 integrated mono valve PA amplifier - 1947+
212:M31 integrated mono valve PA amplifier - 1946+
210:C25 integrated mono valve PA amplifier- 1941+
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308:Quad QC-twentyfour - 2000 to at least 2003
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726:Electronics companies established in 1936
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431:Quad 66 CD - 1989 to 1994 - 13,000 units
403:Quad FMII - 1968 to 1971 - 7,500 units-
366:Quad QA12/P - 1949 to 1951 - 1,000 units
298:Quad 33 – 1967 to 1982 – 120,000 units
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435:Quad 77 CD - 1996 to 1999 - 3,500 units
433:Quad 67 CD - 1993 to 1996 - 6,100 units
390:Quad AMII - 1960 to 1969 - 10,000 units
347:Quad 405–2 1982 to 1993 – 100,000 units
304:Quad 66 – 1986 to 1997 – 12,000 units
302:Quad 44 – 1979 to 1989 – 40,000 units
300:Quad 34 – 1982 to 1995 – 41,000 units
409:Quad 66FM - 1991 to 1996 - 5,100 units
407:Quad FM4 - 1982 to 1995 - 37,000 units
405:Quad FM3 - 1971 to 1982 - 50,000 units
370:Quad 99 Stereo - 1999 to at least 2003
351:Quad 606 – 1986 to 1997 – 27,700 units
349:Quad 306 – 1986 to 1995 – 25,000 units
345:Quad 405 – 1975 to 1982 – 64,000 units
334:Quad 50E - 1966 to 1983 - 12,000 units
317:Quad 303 – 1967 to 1985 – 94,000 units
148:Walker was quoted in December 1975 in
126:. In 1936 the name was changed to the
411:Quad 77FM - 1996 to 1999 - 1,500 unts
401:Quad FM - 1955 to 1967 - 25,000 units
392:Quad AM3 = 1969 to 1973 - 2,000 units
357:Quad 909 Mono - 1999 to at least 2003
353:Quad 707 - 1997 to 1999 - 4,500 units
332:Quad II - 1953 to 1970 - 90,000 units
7:
388:Quad AM - 1954 to 1970 - 2,500 units
372:Quad 99 Mono - 2000 to at least 2003
319:Quad 77 - 1996 to 1999 - 2,500 units
137:The company initially produced only
386:Quad HR1 - 1949 to 1951 - 500 units
330:Quad I - 1951 to 1953 - 2,000 units
437:Quad 99 CD - 1999 to at least 2003
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716:Compact Disc player manufacturers
413:Quad 99FM - 1991 to at least 2003
181:, joining its existing brands of
355:Quad 909 - 1999 to at least 2003
341:Current Dumping Power Amplifiers
336:Quad 99 - 2000 to at least 2003
321:Quad 99 - 1999 to at least 2003
165:Acoustical Manufacturing Co. Ltd
128:Acoustical Manufacturing Co. Ltd
306:Quad 99 - 1999 to at least 2003
731:1936 establishments in England
460:Quad Electrostatic Loudspeaker
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706:Audio amplifier manufacturers
288:Control Unit – Pre-amplifiers
110:is a British manufacturer of
22:Quad Electroacoustics Limited
458:In 1957, they released the
418:FM stereo multipex decoders
124:S.P. Fidelity Sound Systems
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640:Quad: The Closest Approach
450:Quad electrostatic speaker
721:Loudspeaker manufacturers
464:electrostatic loudspeaker
326:Monobloc Power Amplifiers
194:International Audio Group
169:QUAD Electroacoustics Ltd
90:International Audio Group
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676:http://www.iaggroup.com/
522:Hill, Jonathan (1995).
368:Quad 77 - 1994 to 1999
313:Stereo Power Amplifiers
264:Quad II power amplifier
206:Public Address products
150:Wireless World magazine
41:Private limited company
691:http://www.quadesl.org
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228:Source: Audio! Audio!
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638:Ken, Kessler (2003).
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362:Integrated Amplifiers
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256:Quad 33 pre-amplifier
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108:QUAD Electroacoustics
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16:British hi-fi company
167:changed its name to
100:www.quad-hifi.co.uk
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143:sound reproduction
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118:Corporate history
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62:Headquarters
38:Company type
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700:Categories
649:0954574206
533:0951144855
498:References
427:CD players
183:Wharfedale
66:Huntingdon
397:FM tuners
382:AM tuners
189:, China.
187:Shenzhen
76:Products
46:Industry
96:Website
70:England
54:Founded
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473:LS3/5A
377:Tuners
278:tuners
85:Parent
238:valve
112:hi-fi
644:ISBN
528:ISBN
273:and
57:1936
242:BBC
179:plc
702::
542:^
275:FM
271:AM
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