On the websites of audio companies, in information and advertising materials, you can often find the word “legendary”, which, as a rule, is perceived as nothing more than a figure of speech, a verbal seasoning. If there are legends in the world of High Fidelity, there are only a few of them, and the first name that comes to mind is QUAD. If we talk about great audio engineers, then the first of them is QUAD founding father Peter Walker. The QUAD brand has produced at least three outstanding audio components in the last century: the QUAD II power amplifier (1953) and the ESL-57 electrostatic speaker systems (the first full-range commercial ES system, 1957) and ESL-63 (1982).
The history of QUAD dates back to 1936 – then the company “SP Fidelity Sound Systems” was founded, which soon changed its name to “Acoustical Manufacturing Company” – this year marks the diamond, 75th anniversary of QUAD. The company’s founder, twenty-year-old Peter James Walker, was educated at the privileged Oundle School and worked for EMI (Electrical and Music Industries) and GEC (General Electric Company).
Peter James Walker
“No, I didn’t start producing audio equipment right away, that was later,” Walker said. – I collaborated with a company that sold amplifiers. Once, having sold an amplifier for thirty pounds, I thought that all the components were worth no more than five pounds, and I could buy them, assemble the amplifier, sell it and make a profit of twenty-five pounds. Walker’s first products were public address systems. In 1937 or 1938 he designed an amplifier: a push-pull triode circuit with negative feedback, 25 W. After the war, the first acoustic system appeared, the so-called. “Corner ribbon”: the hybrid model consisted of electrostatic panels and a bass driver in a corner acoustic design. In 1949, the QA12/P amplifier was released – the first product with the name QUAD (Quality Amplifier Domestic), in 1953 – the preamplifier and power amplifier QUAD II (the power amplifier is produced today). These were followed by the QUAD 22 preamplifier (1959) and the QUAD 33/303 preamplifier and power amplifier (1967). 1950s-60s British audiophiles became more comfortable pronouncing the acronym “QUAD” rather than “Acoustical Manufacturing Company”. At that time, a legend was born.
“Since about 1945 I had been thinking about the electrostat as the most suitable way to create high-quality acoustics,” recalled Peter Walker. It is worth mentioning here the collaboration of Walker and J. Briggs (the eminent audio engineer, founder of Wharfedale), who conducted “Recording and Live Sound Comparison” demonstrations as part of a world tour. In 1954, Professor Hunt published a paper in which, bringing together a number of ideas that had appeared in the field of sound reproduction over the past thirty years, he gave a rigorous mathematical justification for the advantages of the electrostatic converter. Walker undoubtedly read this treatise, and in 1955 a series of his articles entitled “Wide Range Electrostatic Loudspeakers” appeared in the authoritative magazine Wireless World (May, June and August issues). A few months later, everything was ready for the production of the speaker system, now known as the ESL-57 and at the turn of the 20th and 21st centuries called “the greatest hi-fi product of all time.”
Quad II Amplifier (1953)
The product is based on American patents of 1955 and 1957, which is why the model was called either ESL-57 or ESL-55, but for its creators, engineers Walker and Williamson, it was simply “QUAD Electrostatic Loudspeaker”. The QUAD ESL, as well as the QUAD II monoblock, created the foundation for QUAD’s rapidly growing reputation and had a significant impact on the audio industry. Since that time, QUAD ESL has served as the standard for most speaker designers. The model was produced for a quarter of a century until it was replaced in 1982 by another, without exaggeration, great model: QUAD ESL-63 (according to Walker himself, the idea of creating it came to him in 1963). In the central part of the ESL-63 membrane there are ring electrodes that receive signals alternately (from the center to the periphery) through delay lines. Thus, the speaker system generates a spherical wave centered at a virtual point behind the speaker. “It sounded magical,” Stereophile editor-in-chief John Atkinson recalled of Walker’s first audition of the ESL-63.
Quad ESL 57 (1957)
Peter Walker summarized the design concept for the ESL-63 in a paper at the Audio Engineering Society meeting in June 1979. With characteristic modesty, he claimed that he had not discovered anything new. In the report, Walker referred to Kellogg’s 1929 patent, which proposed the use of several electrostatic elements connected by inductors acting as delay lines; mentioned Shorter of the BBC, who described the connection of ring electrodes using resistors in a 1941 patent, as well as Arthur Jansen, who proposed a similar design in 1953. The earliest information about an electrostatic converter in the literature dates back to 1912. British scientist Richardson worked on detecting underwater objects using electrostatic sensor Richardson’s thoughts were picked up by the Frenchman, an emigrant from Russia, Konstantin Shilovsky; he managed to arouse interest in the idea among the outstanding French physicist Paul Langevin, who began to conduct research in this direction. In 1920, Shilovsky and Langevin received a patent under the name “Production of Submarine Signals and the Location of Submarine Objects.” However, in the field of underwater exploration, the electrostatic converter was not successful and around 1916 it was replaced by a piezoelectric device. In 1918, an electrostat was used in the manufacture of a condenser microphone. During the decade 1925–1935, several patents and articles appeared on this topic: among them the patents of Frederick Lee (1925) and Walter Haneman (1926) – Walker and Williamson based their work on the ideas outlined in them. The progress of the electrostat at that time was minimal – the first simple example of an ES converter appeared only in 1929. To a large extent, the difficulties were due to the lack of suitable materials with the required physical properties. Early patents included gelatin, Japanese lacquer, gold foil, silk, gutta-percha and rubber. Mylar, which is indispensable today, appeared only in 1949 (Du Pont patent), and before that it was proposed to make diaphragms from thin wire and even mosquito nets. A thin metal sheet on a gelatin substrate was used as a conductive coating on the diaphragm.
In 1931, Edelman made an electrostatic speaker using gold foil, Japanese lacquer and stretched thin wire strands. As mentioned above, Kellogg’s developments, described in the 1929 patent, were very important. The popular magazine Wireless World often published interesting articles on loudspeakers, and one of the 1929 articles by Hans Vogt, entitled “The Vogt Electrostatic Loudspeaker” (” Voight’s Electrostatic Loudspeaker”), apparently caught the eye of thirteen-year-old Peter Walker, having a great influence on him and Williamson, who cited Voight’s 1932 patents. Mention should be made within this topic of Arthur Jansen, who in 1959 proposed a then-unique a method of manufacturing stators not from perforated metal, but from wire weaving. At the time, the possibility of combining a Jansen electrostatic tweeter with an Acoustic Research AR-1 minimonitor was enthusiastically discussed. One of the notable electrostatic models of that period was the KLH-9 designed by Jansen. The pinnacle of development of the electrostatic converter, as already mentioned, was the QUAD model. Peter Walker passed away on December 12, 2003. For true lovers of true sound, this day became the day of remembrance of Peter Walker. The QUAD team honors the great engineer and does not break with tradition. The ESL-63 was replaced by new generations of electrostatic speakers: first the ESL-988/989 (still produced today, the Classic line), and then the ESL-2805/2905 (Reference series). Electrostats ESL-2805 and ESL-988 are based on the ESL-63. The ESL-2905 received the prestigious EISA Award for Excellence in Audio – Best Product of the Year 2007-08.
Quad ESL 2912 (2014)
The QUAD II monoblock (QUAD II Classic version) is still produced. The Classic series includes the QUAD II Forty (40 W) and QUAD II Eighty (80 W) tube monoblocks, as well as the QC 24 preamplifier, QC 24P phono stage (designed by Tim de Paravicchini) and the QUAD II Integrated Amplifier. The combination of ESL-2805 with QUAD II monoblocks is the most musical the author of this review has ever encountered. Even taking into account a number of objective limitations, the sound is extremely impressive. The company also offers transistorized hi-fi electronics and dynamic speaker systems – these products are grouped into the Performance Series divisions. The famous and very successful 99 Series has been replaced by the Elite line, which includes two CD players (Elite CDS and Elite CDP), an Elite FM tuner, an Elite Pre-Amp, an Elite Stereo power amplifier and an Elite Mono block. The Performance Series also offers Hi-Fi speakers (L2 Series includes mini-monitor and floor-standing speakers), active speakers (L-Active), L-ite multi-channel (5.1) acoustic configuration and the L-ite Plus LCR soundbar.