 | |
| Company type | Private limited company |
|---|---|
| Industry | Home entertainment equipment manufacturing & distribution |
| Founded | 1936 |
| Headquarters | Huntingdon, Cambridgeshire |
| Products | Hi-fi equipment |
| Parent | International Audio Group |
| Website | www.quad-hifi.co.uk |
QUAD Electroacoustics is a British manufacturer of hi-fi equipment, based Huntingdon, Cambridgeshire. QUAD is part of the IAG Group, with corporate headquarters located in Shenzhen, China.
The company was founded by Peter J. Walker in 1936 in London, and was initially called S.P. Fidelity Sound Systems. In 1936 the name was changed to the Acoustical Manufacturing Co. Ltd. The company moved from London to Huntingdon in 1941 after being bombed out of London in World War II.
The company initially produced only public address 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 sound reproduction. Within a few years the company had transitioned almost entirely to manufacturing models for the home audio market.
Walker was quoted in December 1975 in Wireless World magazine, "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."[ citation needed ]
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 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.
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.[ citation needed ]
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 Acoustical Manufacturing Co. Ltd changed its name to QUAD Electroacoustics Ltd.
In 1995, QUAD Electroacoustics Ltd was bought by Verity Group plc, joining its existing brands of Wharfedale and Mission. A few changes were made, including shifting all production to Shenzhen, China. [1]
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 International Audio Group under the management of Bernard and Michael Chang.
In 2003, a book was commissioned "QUAD:The Closest Approach" which offered a history of the company from its creation to that point.
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.
The company's first major products were released in 1948. The QA12 and QA12/P were low-powered mono valve 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 BBC. This valve power amplifier featured a cathode-coupled winding dating from 1943, which eventually became the Quad II. The QII preamplifier accompanied it. [2]
Following the mass production of 'stereo' vinyl records in 1958, the QC 22 control unit was developed and released in 1959. [2] 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 AM and FM tuners for use with the QC II & 22 control units. [2]
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.
Quad 33 – 1967 to 1982 – 120,000 units [2]
Quad 34 – 1982 to 1995 – 41,000 units [2]
Quad 44 – 1979 to 1989 – 40,000 units [2]
Quad 66 – 1986 to 1997 – 12,000 units [2]
Quad 99 - 1999 to at least 2003 [2]
Quad 303 – 1967 to 1985 – 94,000 units [2]
Quad 50E - 1966 to 1983 - 12,000 units [2]
Quad 405 – 1975 to 1982 – 64,000 units [2]
Quad 405–2 1982 to 1993 – 100,000 units [2]
Quad 306 – 1986 to 1995 – 25,000 units [2]
Quad 606 – 1986 to 1997 – 27,700 units [2]
Quad 707 - 1997 to 1999 [2]
Quad 909 - 1999 to at least 2003 [2]
Quad 77 - 1994 to 1999 [2]
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.
In 1957, they released the Quad Electrostatic Loudspeaker (ESL), the first production full frequency range electrostatic loudspeaker 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 could result in damage to either or both.
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 LS3/5A, that were more easily transported and stored, and were more representative of typical contemporary hi-fi speakers.
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 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.
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.
Many of Quad's products, including the Quad Electrostatic Loudspeaker (ESL-57), are still serviced by the company's Service Department in Huntingdon.
A loudspeaker 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 loudspeaker, comprises one or more such speaker drivers, an enclosure, and electrical connections possibly including a crossover network. The speaker driver can be viewed as a linear motor attached to a diaphragm which couples that motor's movement to motion of air, that is, sound. An audio signal, typically from a microphone, recording, or radio broadcast, is amplified electronically to a power level capable of driving that motor in order to reproduce the sound corresponding to the original unamplified electronic signal. This is thus the opposite function to the microphone; indeed the dynamic speaker driver, by far the most common type, is a linear motor in the same basic configuration as the dynamic microphone which uses such a motor in reverse, as a generator.
An audio power amplifier amplifies low-power electronic audio signals, such as the signal from a radio receiver or an electric guitar pickup, to a level that is high enough for driving loudspeakers or headphones. Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address, home audio systems and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers.
An audiophile is a person who is enthusiastic about high-fidelity sound reproduction. An audiophile seeks to reproduce recorded music to achieve high sound quality, typically in a quiet listening space and in a room with good acoustics.
A tweeter or treble speaker is a special type of loudspeaker that is designed to produce high audio frequencies, typically up to 100 kHz. The name is derived from the high pitched sounds made by some birds (tweets), especially in contrast to the low woofs made by many dogs, after which low-frequency drivers are named (woofers).
An electrostatic loudspeaker (ESL) is a loudspeaker design in which sound is generated by the force exerted on a membrane suspended in an electrostatic field.
Audio system measurements are a means of quantifying system performance. These measurements are made for several purposes. Designers take measurements so that they can specify the performance of a piece of equipment. Maintenance engineers make them to ensure equipment is still working to specification, or to ensure that the cumulative defects of an audio path are within limits considered acceptable. Audio system measurements often accommodate psychoacoustic principles to measure the system in a way that relates to human hearing.
An instrument amplifier is an electronic device that converts the often barely audible or purely electronic signal of a musical instrument into a larger electronic signal to feed to a loudspeaker. An instrument amplifier is used with musical instruments such as an electric guitar, an electric bass, electric organ, electric piano, synthesizers and drum machine to convert the signal from the pickup or other sound source into an electronic signal that has enough power, due to being routed through a power amplifier, capable of driving one or more loudspeaker that can be heard by the performers and audience.
The Williamson amplifier is a four-stage, push-pull, Class A triode-output valve audio power amplifier designed by D. T. N. Williamson during World War II. The original circuit, published in 1947 and addressed to the worldwide do it yourself community, set the standard of high fidelity sound reproduction and served as a benchmark or reference amplifier design throughout the 1950s. The original circuit was copied by hundreds of thousands amateurs worldwide. It was an absolute favourite on the DIY scene of the 1950s, and in the beginning of the decade also dominated British and North American markets for factory-assembled amplifiers.
Founded by David Hafler and Ed Laurent in Philadelphia, Pennsylvania in 1955, Dynaco was an American hi-fi audio system manufacturer popular in the 1960s and 1970s for its wide range of affordable, yet high quality audio components.. Its best known product was the ST-70 tube stereo amplifier. They also manufactured other tube and solid state amplifiers, preamplifiers, radio tuners and bookshelf loudspeakers. Dynaco was liquidated in 1980, and the trademark is now owned by Radial Engineering Ltd.
Robert W. (Bob) Carver is an American designer of audio equipment based in the Pacific Northwest.
A headphone amplifier is a low-powered audio amplifier designed particularly to drive headphones worn on or in the ears, instead of loudspeakers in speaker enclosures. Most commonly, headphone amplifiers are found embedded in electronic devices that have a headphone jack, such as integrated amplifiers, portable music players, and televisions. However, standalone units are used, especially in audiophile markets and in professional audio applications, such as music studios. Headphone amplifiers are available in consumer-grade models used by hi-fi enthusiasts and audiophiles and professional audio models, which are used in recording studios.
Roksan is a British manufacturer of high fidelity audio products for domestic use, based in Rayleigh, Essex. It is best known for its influential and innovative design for hi-fi equipment, and in particular its Xerxes platform for playing LP records.
A valve audio amplifier (UK) or vacuum tube audio amplifier (US) is a valve amplifier used for sound reinforcement, sound recording and reproduction.
Radford Electronics is a British audio manufacturer from Bristol, founded by Arthur Hedley Radford (G6YA) in 1946. Radford's hi-fi amplifiers enjoyed a reputation for quality that was "second to none", especially because of their output transformers.
Technical specifications and detailed information on the valve audio amplifier, including its development history.
The Braun LE1, Loudspeaker Unit 1, was the first electrostatic mode loudspeaker available on the German hi-fi market. German electronics company Braun started production in 1960 with the technology licensed from the British Acoustical Manufacturing Co. Ltd..
Crown International, or Crown Audio, is an American manufacturer of audio electronics, and is a subsidiary of Harman International Industries, which has been part of South Korea-based Samsung Electronics since 2017. Today, the company is known primarily for its power amplifiers, but has also manufactured microphones, loudspeakers, and a line of commercial audio products, as well as digital audio networking products.
Home audio refer to audio consumer electronics designed for home entertainment, such as integrated systems like shelf stereos, as well as individual components like loudspeakers and surround sound receivers.
The NAD 3020 is a stereo integrated amplifier by NAD Electronics, considered to be one of the most important components in the history of high fidelity audio. Launched in 1978, this highly affordable product delivered a good quality sound, which acquired a reputation as an audiophile amplifier of exceptional value. By 1998, the NAD 3020 had become the most well known and best-selling audio amplifier in history.
The Quad Electrostatic Loudspeaker (ESL) is the world's first production full-range electrostatic loudspeaker, launched in 1957 by Quad Electroacoustics, then known as the Acoustical Manufacturing Co. Ltd. The speaker is shaped somewhat like a home electric radiator curved slightly on the vertical axis. They are widely admired for their clarity and precision, but known to be difficult speakers to run and maintain.
