Quad Electroacoustics

Quad Electroacoustics

Infobox Company
company_type = private limited company

foundation = September 14, 1978
location = Huntingdon, Cambridgeshire, England
key_people =
industry = Home entertainment equipment manufacturing & distribution
parent = Verity Group plc
products = Hi-fi equipment
homepage = [http://www.quad-hifi.co.uk/ www.quad-hifi.co.uk]
footnotes =

Quad Electroacoustics is a British manufacturer of hi-fi equipment, based in Huntingdon, England.

Corporate history

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.

The name "QUAD" is an acronym for "Quality Unit Audio 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 some loudspeaker production to East China, but the company essentially stayed the same, and still tries to adhere to its ethos of "the closest approach to the original sound".

Audio products

The company’s first 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.


Following the development of stereo 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 amplifiers. To complement the QUAD II, the company also produced AM and FM tuners for use with the QC II & 22 control units.

The company made the transition to transistor-powered models in the 1970s, initially with the 33/303 preamplifier/power amplifier combo and later with the 44/405 and subsequent 606 and 909 models. They also made a range of AM and FM tuners.

Product Range - "Please add dates of manufacture"

Control Unit - Pre Amplifiers Quad 44 Quad 34 Quad 66 Quad 77 Quad 99

Current Dumping Power Amplifiers Quad 405Quad 405-2Quad 306Quad 606Quad 707Quad 909

Other (Conventional) Power Amplifiers Quad 303Quad 77 Integrated


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 a electromagnetic ribbon loudspeaker, designed by Acoustical, for the higher frequencies. Fewer than one thousand units were sold.

In 1957, the company made history when they released the world's first production full frequency range electrostatic loudspeaker. This unit is now referred to by enthusiasts as the ESL-57, although the company did not refer to it by that name. It used ultra-thin stretched PET film as the main component of its drive units. The PET film is coated with a mildly electrically conductive paste and is sandwiched between 2 stators. A very high voltage is applied to the PET film and to the stators. Sound is produced by varying the charge on the stators to set the PET film in motion. Two bass panels flank one treble panel to provide full range sound.

The ESL-57 design, renowned as it was (and still is) for its sonic transparency and very low distortion, has a very small 'sweet spot' where the sound stage snaps into focus, moderate power handling, the need for a large room, and moderate bass extension. Quad addressed these limitations to some degree with the ESL-63, introduced in 1981. The newer design featured larger panels and a groundbreaking stator design, made up of eight concentric rings fed from the center outwards through analogue delay lines, so that the audio signal radiated out as though coming from a single point. Subsequent electrostatic models, the 988/989 and then the 2805/2905 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 along its electrostatic line, available in both passive and active (i.e. featuring in-box amplification) configurations.

Remarkably, customer demand resulted in manufacture of the ESL-57 continuing in the UK until 1996. The tooling was then bought by QUAD's representative in Germany, QUAD Musikwiedergabe [http://www.quad-musik.de/] , who continue to manufacture complete speakers and spare parts, and overhaul customers' speakers.

Bass extension of the ESL-57s can be improved by means of one or two sub-woofers [http://loudspeaker-repair-service.reromanus.net/refurbish_quad.htm] , or, if space and appearance permit, by stacking them in pairs, one above the other [http://www.quad-musik.de/html/quadfest_20081.html] .


Quad have always had a very straightforward engineering view of their products, and insisted that all amplifiers sounded the same when used within their capabilities, and that speaker cable had no sound at all, unless ludicrously long and thin wire is used.

The company's founder, Peter J. Walker, died in 2003 at the age of 87. He had retired in the late 1980s, then turning management over to his son, the engineer Ross Walker.


*1936, "S.P. Fidelity Sound Systems" founded by Peter J. Walker.
*1936, The company name changed to the "Acoustical Manufacturing Co. Ltd".
*1941, The company moved to Huntingdon.
*1948, The QA12/ QA12/P amplifiers - the first product for domestic (consumer) market
*1950, QUAD I, (15 watt mono amplifier) released. Discontinued 1953.
*1953, launched the QUAD II amplifier, made until 1970.
*1957, released the ESL, the world's first production full-range electrostatic loudspeaker, later referred to as the ESL-57. Technology licensed to Braun company Germany in 1959 (loudspeaker BRAUN LE1)
*1959, the QC 22 stereo control unit released along with separate AM and FM tuners.
*1966, launched the first mono transistor amplifier, the 50 and 50/E, for the professional market.
*1967, launched 303 stereo amplifier for domestic use, accompanied by the all-transistor QUAD 33 control unit. Discontinued around 1985.
*1975, The QUAD 405 power amplifier released. replaced by the 405-2 in 1982. The 405-2 was discontinued 1993.
*late 1970’s , released two new control units - the QUAD 34 and 44.
*1983, changed its name to "QUAD Electroacoustics Ltd".
*1981, new electrostatic loudspeaker, the ESL-63.
*mid-80s , released the QUAD 66/606 system, along with the first QUAD CD player.
*1993, launched the 77 series.
*1993, launched the L series dynamic loudspeakers.
*1995, QUAD Electroacoustics Ltd acquired by Verity Group plc, joining its existing brands, Wharfedale and Mission
*1996, Manufacture of ESL-57 transferred to "QUAD Musikwiedergabe".
*1999, QUAD released the QUAD 99 system; resurrected the legendary QUAD II and the QUAD II-Forty
*2000, QUAD released the ESL-988 and ESL-989, based on the legendary ESL-63
*2006, QUAD released the ESL-2805 and ESL-2905, redesigned versions of the ESL-988 and ESL-989.
*2006, QUAD released the L2 series loudspeakers.

External links

* [http://www.quad-hifi.co.uk/ Quad] - The official Quad site
* [http://user.tninet.se/~vhw129w/mt_audio_design/quad_tweaks.htm Quad tweaks]
* [http://www.fidele.co.uk/ UK Quad amplifier upgrades and service]
* [http://loudspeaker-repair-service.reromanus.net/refurbish_quad.htm EU Quad ESL repair and upgrade]
* [http://www.quadesl.org The Quad ESL-The Complete Reference]
* [http://www.quad-musik.de/html/quad_english.html QUAD Musikwiedergabe]

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