The Hub: QUAD ESL-57, Some good things last a lifetime.
In nearly 40 years of audiophilia, only a few demos have altered my perspective on audio. The three most memorable demos were significant because of the speakers used: one featured Magneplanar Tympanis, another featured Hill Plasmatronics. The third game-changing demo utilized the speaker which has probably beguiled and bewildered more music-lovers and audiophiles than any other, the original QUAD electrostatic, often referred to as the ESL-57.
Like FIAT and SAAB, "QUAD" is an acronym, representing the military-sounding phrase Quality Unit Amplifier, Domestic. Blair Roger's excellent "Quad ESLs : Then and Now
" page tells us that the company we now think of as QUAD got its start in 1936, when Peter Walker founded S.P. Fidelity Sound Systems. Within two years, the company had become The Acoustical Manufacturing Company, producing a portable public-address system. Home hi-fi followed, with a tuner, pre-amp and amp; the majority of production during WW II was the portable P.A.. After the war, QUAD produced a corner-horn speaker utilizing a moving-coil woofer made by British speaker-manufacturer Goodmans, and a ribbon tweeter made by Acoustical.
1953 was a big year for England: Queen Elizabeth ascended to the throne, a British subject climbed Everest, and QUAD introduced the model II power amplifier, a replica of which is still made today. In 1956, QUAD first publicly showed their electrostatic speaker, which had been under development for half a dozen years. Interestingly enough, at the same show Goodmans' chief designer, E.J. "Ted" Jordan, also exhibited a full-range electrostatic loudspeaker (ESL). Unlike Goodmans' design, QUAD's ESL became a landmark product which revolutionized the worlds of home music reproduction, industrial design, and commerce.
The QUAD electrostatic was, like all electrostats, essentially a capacitor. A conductive plastic film which acts as the diaphragm of the speaker is positioned between perforated metal grids. A charge is maintained on the diaphragm, and as the high voltage to the plates/grids varies with the music signal, the diaphragm moves, producing sound. In the QUAD ESL-57, the speaker utilizes a step-up transformer to couple output of an amplifier to the plates. Unlike many ESLs, the QUAD is not a "one-way" design, but has a tweeter panel surrounded by woofer panels on its left and right. This gives the ESL-57 limited dispersion, creating a tightly-focused "sweet-spot".
Compared to most contemporary speakers, the QUAD 'stat produced a startlingly clear and well-defined sound, yet was totally lacking in the etched quality audiophiles often associate with "definition". Its design and construction placed restrictions on both ultimate volume capabilities and bass-extension; rather like a tube amplifier, when the QUAD ESL was overdriven, dynamic contrasts flattened out, distortion increased, and it just didn't get any louder. If the speaker was badly overloaded, however, it was possible for the diaphragm to short out (or "arc") against the grids, producing a crackling noise, accompanied by a flash and a stench of scorched plastic if it was really REALLY overdriven.
Peter Walker himself sought to overcome the issues of limited bass and the restricted "sweet-spot" with his next design, the ESL-63. Design of the new model began in 1963, as the nomenclature hints, but a production model wasn't introduced until 1981! That gives a pretty decent idea of how difficult Walker found it to improve upon his first ESL. The ESL-63 succeeded in producing more bass by utilizing a larger radiating-area and dipole radiation, and a delay-line created a wider dispersion-pattern by initiating the signal at the center of the diaphragm, radiated outward to the edge, mimicking the expanding concentric rings created by a rock thrown into a pond. The '63 did succeed in overcoming many of the '57's liabilities; nonetheless, many listeners today still prefer the tonal balance and immediacy of the original model.
QUAD produced both models simultaneously for a few years, ultimately ceasing production of the ESL-57 in 1985. Such are the capabilities of both speakers that new versions of both the '57 and '63 are still produced under license in Germany by QUAD Musikwiedergabe
, a pair of which are listed for sale here
. While certain technical and material deficiencies of the originals have been addressed, the "New Old" German models are said to faithfully adhere to the character and abilities of the original speakers.
QUAD continues today as part of the massive International Audio Group Ltd. (IAG
), along with fellow veteran British brands Wharfedale, Leak, Castle and Mission. QUAD ESLs are made in China, these days, although R&D and design appear to still be in the U.K. It's remarkable how, given the far-flung locales of their production, the company still seems quintessentially British.
if you wish to learn more about Quad then check out the family tree in our Bluebook
and be sure to search the Audiogon Forums
for tons of info from experienced Quad owners.