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Area 51

Rare and Special materials not available elsewhere
 
 
 
 
 

Fixit

Techniques explained, parts, suppliers and weird shit.
 
  • Introduction

    The Quad ESL was the world's very first full range, commercially available electrostatic loudspeaker. In spite of its great antiquity (some 50 years old to date) it was voted the "Greatest Hi-Fi Product of All Time" by Hi-Fi News and record review in the January 2000 issue of that journal. Read More
  • FixIt

    The Quad Electrostatic Loudspeaker is one of those very, very few things that you may own which is about 20 to 30 years old, that you would want to spend any time restoring to original condition. However, it seems that there's quite a few folks out there who still prize Read More
  • Parts

    All the very special materials like diaphragm film (6 micron) and coatings - CALATON and ELVAMIDE - have 'moved' to Area 51. You'll find special 'kits' there also, along with dust cover material and the pride of the site, some tensilised 6-micron treble panel film and 12-micron PVC bass panel film, at Read More
  • Amplifiers

    If there was ever a contentious topic of discussion not directly involved with the Quad electrostatic speaker itself, then this is it. I think I have seen and read more correspondence on the matter of amplifiers than everything but the coating material on the diaphragms and the "Did they coat Read More
  • Patents

      Filed: July 15, 1955 U.S. Patent 3,008,013Granted: November 7, 1961 David Theodore Nelson Williamson, Edinburgh, Scotland assigned rights to Ferranti Ltd., London. Peter James Walker of Huntingdon, England."Electrostatic Loudspeakers" Read More
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Popular Articles

  • Introduction >

    The Quad ESL was the world's very first full range, commercially available electrostatic loudspeaker. In spite of its great antiquity Read More
  • PK Panels >

    Wayne Picquet in Florida, U.S.A. has been rebuilding original Quad ESL panels since about 2002. From pretty humble beginnings, like Read More
  • Christian Steingruber >

    Amplification for Quads - Fifth Edition by Christian Steingruber "All amplifiers sound the same" - Peter Walker "Amplifiers DO sound different" - Martin Read More
  • Walker & Albinson 1976 U.S. >

    Filed: January 10, 1975U.S. Patent 3,970,953Granted: July 20, 1976 "Distortion-Free Amplifiers"Peter James Walker and Michael Peter Albinson Read More
  • Wiring Diagrams >

    You've taken the old Quads apart and Holy Shit(!) Batman, the wiring is NOT colour-coded!! What can you do? The Read More
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Interviews and Reviews

  • icon Walker 1978
  • icon AES Lecture
  • icon Mike Albinson
  • icon Hi Fi News 1957
  • icon Quad 410
  • icon Audio Critic 1980
  • icon Sound Practices 1994
  • icon Classic Hi Fi 1996
  • icon The Listener 1998
  • icon The Audiophile 1998
  • icon Wayne's Drama
  • icon OTLs and Quad
  • icon Futterman OTL
  • icon Gang of Five

'Audio Amateur'

Interviews Peter Walker at the Quad Factory in 1978

TAA: What do you consider to be the important goals of a good audio reproduction system what ought a good audio reproduction system do?

PW: Well, perhaps this reflects my age (62 at the time of the interview), but I am still in favour of documentary type reproduction - an orchestra plays on a stage

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Click the images below (l to r) in succession to see Walker's address to the U.K. Audio Engineering Society in 1979 on the Quad ESL 63

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ACOUSTICAL MANUFACTURING's Mike Albinson, co-designer of the revolutionary Quad 405 power amplifier, and outspoken critic of many current fashionable amplifier theories, is our subject this month.

Practical Hi-Fi: The Quad 405 represents something fairly unique in modern Hi-Fi amplifier design. What led you to the concept of feed-forward instead of the more normal feedback?

Mike Albinson: Difficult question, but I have a stock answer to

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The Quad Electrostatic Speaker

by Ralph West

The recent appearance of a full range ESL designed and produced by a well-known manufacturer specialising in high quality reproduction, was bound to cause considerable comment and speculation. This speaker, the "Quad" electrostatic, is now in production, and we are pleased to present our readers with a full review of a specimen drawn from current production. The makers

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No, Quad have not capped off their recent release of the ESL 63 speaker with a new amplifier! The 410 is in fact the designation given to the 405 power amplifier when its channels are bridged together to give a mono amplifier of effectively 180 watts. In fact, it is even possible to bridge a pair of these 410 amplifiers to give a mono amplifier

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The AUDIO-CRITIC Volume 2, Number 3 (Spring to Fall 1980) wrote:

QUAD ELECTROSTATIC LOUDSPEAKER

"This all-time classic needs no introduction to any audiophile who knows enough to read equipment reviews at all. It has survived virtually unchanged for a quarter of a century (the manufacturer claims there have been no changes whatsoever, large or small, but we take that with a grain of salt); we,

Read More

Sound Practices - 1994

The Quad Electrostatic Loudspeaker

by Haden Boardman / Mellotone Acoustics

A good electrostatic has something special, a magic spell that weaves itself over you. Critics (of which there are few) moan on ~bout "won't play rock" or "only for string quartets". Ask these plaintiffs what system they have, or what kind of speakers, and the usual response is some old west coast monster.

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Hi-Fi News and Record Review, UK.

Classic Hi-Fi, Jun 1996

Restoration Drama by Ken Kessler

In late 1995, the Bugatti Owners' Club produced facsimile reprints of all of the issues of the Club Magazine, Buganacs, issued before WWII. It was telling to read articles from, say, 1938, about the trials and tribulations of working on even 10 year old vehicles, at a time when the

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The Quadfather

In the beginning, there was the Quad ESL, the world's first full-range electrostatic loudspeaker.

An appreciation, by Chris Beeching

Quad ESL loudspeaker: available used for between $600 and $2000 per pair and up, depending on condition. Originally manufactured by Quad Electroacoustics, Huntington, England.Surely the venerable Quad speaker is one of the most enduring of all quality hi-fi products ever made.Since it took the

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Quad ESLs:Then and Now

Blair Roger

Can a loudspeaker be all things to all people? Probably not, but the Quads take a damn good shot at it and I'll dispute anyone who says otherwise.

Genesis

Peter Walker and his engineering team have been unconventional and pragmatic thinkers since S. P. Fidelity Sound Systems was founded in 1936. By 1938 they were manufacturing a portable public

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It was about July 2000 that I received an e-mail from this chap in Florida, U.S.A. He was having some trouble trying to restore an old pair of Quads. The difference between him and a hundred others was that he was really starting from behind square one. By which I mean that these Quads would have made a bona fide ‘expert’ restorer throw up their

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The history of this amp's circuit starts twenty five years ago when Julius Futterman, understanding the limitations of the output transformers. patented an Output Transformerless design. The clarity of the sound has been unsurpassed to this day and a cadre of serious music listeners has remained steadfast to the genius of Julius Futterman. The man was the embodiment of integrity in the audio world and

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Letter to the Editor


(Julius Futterman)

"I am pleased with your evaluation of the sonic virtues of the H-3aa power amplifier but do take exception to two of your assertions :

The power tubes I use (6LF6) are being manufactured in the USA by GE and Sylvania. They are also being made in Japan and Yugoslavia. I have been informed that they will be around for

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Gang of Five

Gary Jacobson

Introduction

Madness strikes at all hours of the day and night, so I can’t tell you exactly when it occurred to me to assemble a collection of treble panels from all the major Quad panel refurbishers and rebuilders, but I suspect it was just a couple of months ago - it seems longer. The panels examined in this review are a

Read More

Original ESL Patents

  • icon Masolle 1921
  • icon Lee 1925
  • icon Depew 1926
  • icon Hahnemann 1928
  • icon Hartley 1928
  • icon Kellogg 1929
  • icon Rauser 1930
  • icon Rauser 1931
  • icon Vogt 1930
  • icon Vogt 1928
  • icon High 1930
  • icon Kellogg 1929/2
  • icon Etablissements S.M. 1946
  • icon Janszen 1949
  • icon Kock 1951
  • icon Curry 1953
  • icon Parker 1954
  • icon Williamson 1955
  • icon Williamson 1957

Filed: November 28, 1921
U.S. Patent 1,550,381
Granted: August 18, 1925

Joseph Masolle, Hans Vogt and Josef Engl assignors to Tri-Ergon Ltd., of Zurich, Switzerland
"Electrostatic Telephone"

Referenced by Walker and Williamson in
U.S. Pat. 3,008,014.

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Filed: May 2, 1925
U.S. Patent 1,622,039
Granted: March 22, 1927

Frederick W. Lee, Owing Mills, Maryland.
"Apparatus for and Method of Reproducing Sound".

Referenced by Walker and Williamson in U.S. Pats. 3,008,013 & 3,008,014.

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Filed: February 12, 1926
U.S. Patent 1,631,583
Granted: June 7, 1927

John Depew, of New York.
"Capacitatively Actuated Loudspeaker".

Referenced by Walker and Williamson in U.S. Pat. 3,008,014

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Filed: March 24, 1926
U.S. Patent 1,674,683
Granted: June 26, 1928

Walter Hahnemann, Kitzberg, Germany, assigned rights to Lorenz Aktiengesellschaft.
"Arrangement for Uniform Electrical Sound Transmission".

Referenced by Walker and Williamson in U.S. Pat. 3,008,013

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Filed: June 6, 1928
U.S. Patent 1,762,981
Granted: June 10, 1930

Ralph V.L. Hartley of South Orange, N.J. assigned rights to Bell Telephone Labs., N.Y.
"Acoustic Device"

Referenced by Walker and Williamson in U.S. Pats. 3,008,013 & 3,008,014

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Filed: Sept. 27, 1929
G.B. Patent 346,646
Granted: April 16, 1931

Edward Washburn Kellogg, Schenectady, N.Y. assigned rights to General Electric Co. N.Y.
"Production of Sound"

Indirectly Referenced by Walker and Williamson in U.S. Pats. 3,008,013

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Filed: February 12, 1930
G.B. Patent 348,573
Granted: May 12, 1931

Albert Rauser and Wilhelm Steuer, of Kottbuser-Ufer 39/40, Berlin, S.O. 26
"Improvements Relating to Electrostatic Loud-speakers".

Referenced by Walker and Williamson in U.S. Pat. 3,008,014

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Filed: June 1, 1931
G.B. Patent 370,248
Granted: April 7, 1932

Albert Rauser and Wilhelm Steuer, of Kottbuser-Ufer 39/40, Berlin, S.O. 26
"Improvements in Electrostatic Loud-speakers".

Referenced by Walker and Williamson in U.S. Pat. 3,008,014

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Filed: Sept. 8, 1930
G.B. Patent 372,649
Granted: May 12, 1932

Hans Vogt, Genthinerstrasse 17, Berlin, W. 35, Germany.
"Improvements Relating to the Insulation of Fixed Electrodes of Electrostatic Loudspeakers"

Indirectly Referenced by Walker and Williamson in U.S. Pat. 3,008,014

Read More

Filed: Sept. 15, 1928
U.S. Patent 1,881,107
Granted: Oct. 4, 1932

Hans Vogt of Berlin-Wilmersdorf, Germany.
"Sounding Condenser"

Referenced by Walker and Williamson in U.S. Pat. 3,008,013. Also ref: GB Patent 322,744 with 17 claims, granted December 10, 1929

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Filed: July 30, 1930
U.S. Patent 1,930,518
Granted: October 17, 1933

Jurjen S. High of Camden, N.J. assigned rights to Westinghouse Electric and Manufacturing Co. Pennsylvania.
"Electrostatic Loudspeaker"

Referenced by Walker and Williamson in U.S. Pats. 3,008,013 & 3,008,014

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Filed: Sept. 27, 1929
U.S. Patent 1,983,377
Granted: December 4, 1934

Edward Washburn Kellogg, Schenectady, N.Y. assigned rights to General Electric Co., N.Y.
"Production of Sound"

Referenced by Walker and Williamson in U.S. Pat. 3,008,013. Also ref: GB Patent 346,646 which pre-dates this grant of patent on the same device.

See prior citation of E.W. Kellogg.

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Filed: April 9, 1946
G.B. Patent 610,297
Granted: Oct. 13, 1948

Etablissements S.M. Body Corporate of 26 Rue de Lagny, Paris.
"Improvements in Electrostatic Microphones and Loud-speakers"

Referenced by Walker and Williamson in U.S. Pat. 3,008,013.

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Filed: October 5, 1949
U.S. Patent 2,631,196
Granted: October 5, 1953

Arthur A. Janszen, Cambridge, Mass.
"Electrostatic Loud-Speaker"

Referenced by Walker and Williamson in U.S. Pats. 3,008,013 & 3,008,014.

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Filed: December 12, 1951
U.S. Patent 2,796,467
Granted: June 18, 1957

Winston E. Kock, Basking Ridge, N.J., assigned rights to Bell Telephone Labs., N.Y.
"Directional Transducer"

Referenced by Walker and Williamson in U.S. Pats. 3,008,013 & 3,008,014.

Read More

Filed: December 11, 1953
U.S. Patent 2,855,467
Granted: October 7, 1958

Paul Curry, New Haven, Connecticut assigned rights to Curry Electronics Inc., New Haven, Conn.
"Loudspeakers"

Referenced by Walker and Williamson in U.S. Pat. 3,008,014.

Read More

Filed: November 29, 1954
U.S. Patent 2,864,899
Granted: December 16, 1958

Henry W. Parker, Flushing, N.Y.
"Transducer"

Referenced by Walker and Williamson in U.S. Pat. 3,008,014.

Read More

 

Filed: July 15, 1955

U.S. Patent 3,008,013
Granted: November 7, 1961

David Theodore Nelson Williamson, Edinburgh, Scotland assigned rights to Ferranti Ltd., London. Peter James Walker of Huntingdon, England.
"Electrostatic Loudspeakers"

Read More

Filed: September 12, 1957
U.S. Patent 3,008,014
Granted: November 7, 1961

David Theodore Nelson Williamson, Edinburgh, Scotland assigned rights to Ferranti Ltd., London. Peter James Walker of Huntingdon, England.
"Electrostatic Loudspeakers"

Read More

ESL 63 Patents

  • icon Kellogg 1929
  • icon Shorter 1940
  • icon Dome 1941
  • icon Harry 1943
  • icon Stolaroff 1948
  • icon Wilkins 1954
  • icon Wilkins 1956
  • icon Macdonald 1958
  • icon Wright 1958
  • icon Wang 1967
  • icon Walker 1970

Filed: September 27, 1929
U.S. Patent 1,983,377
Granted: December 4, 1934

Edward W. Kellogg "Production of Sound"

Referenced by Walker in U.S. Pat. 3,773,984.

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Filed: February 21, 1940

G.B. Patent 537,931
Granted: July 14, 1941

Donovan Ernest Lea Shorter
"Improvements in Electrostatic Loudspeakers"

Referenced by Walker U.S. Pats. 3,773,984.

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Filed: January 28, 1941
U.S. Patent 2,302,493
Granted: November 17, 1942

Robert B. Dome, Bridgeport, Connecticut
"Amplifying System".
 Referenced by Walker in U.S. Pat. 3,773,984.

Read More

Filed: June 24, 1943
U.S. Patent 2,387,845
Granted: October 30, 1945

William R. Harry, Summit, New Jersey
"Electroacoustic Transducer".

Referenced by Walker U.S. Pat. 3,773,984.

Read More

Filed: December 18, 1948
U.S. Patent 2,634,335
Granted: April 7, 1953

Myron B. Stolaroff, Redwood City, California assignor to Ampex Corporation
"Magnetic Recording System with Negative Feedback System."

Referenced by Walker U.S. Pat. 3,773,984.

Read More

Filed: May 19, 1954
U.S. Patent 2,843,671
Granted: July 15, 1958

Charles A. Wilkins and Herbert Sullivan, New York
"Feed Back Amplifiers"

Referenced by Walker in U.S. Pats. 3,773,984

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Filed: August 29, 1956
U.S. Patent 2,905,761
Granted: September 22, 1959

Charles A. Wilkins, New York.
"Control of Amplifier Source Resistance"

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Filed: September 9, 1958
U.S. Patent 3,061,675
Granted: October 30, 1962

James Ross Macdonald
"Loudspeaker Improvement"
[
Claims 1-5], [Claim 5 ]. Diagrams:[Sheet 1] [Sheet 2]
Referenced by Walker in U.S. Pat. 3,773,984.

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Filed: December 10, 1958
U.S. Patent 3,135,838
Granted: June 2, 1964

William M. Wright, Boston Mass.
"Electrostatic Loudspeaker"

Referenced by Walker in U.S. Pat. 3,773,984.

Read More

Filed: May 18, 1967
U.S. Patent 3,542,952
Granted: November 24, 1970

Chien San Wang, Denver, Colorado
"Low Distortion Signal Reproduction Apparatus"
 
Referenced by Walker in U.S. Pat. 3,773,984.

Read More

Filed: November 3, 1970
U.S. Patent 3,773,984
Granted: November 20, 1973

Peter James Walker of Huntingdon, England.
"Electrostatic Loudspeaker with Constant Current Drive"

Read More

Quad 405 Patents

  • icon Ketchlidge 1956
  • icon Walker & Albinson 1976 U.S.
  • icon Walker & Albinson 1976 G.B.

Filed: September 26, 1952
U.S. Patent 2,751,442
Granted: June 19, 1956

Raymond W. Ketchlidge

"Distortionless Feedback Amplifier"
Referenced by Walker in U.S. Pat. 3,773,984.

Read More

Filed: January 10, 1975
U.S. Patent 3,970,953
Granted: July 20, 1976

"Distortion-Free Amplifiers"
Peter James Walker and Michael Peter Albinson

Read More

 

Filed: January 10, 1975
U.S. Patent 3,970,953
Granted: July 20, 1976

"Distortion-Free Amplifiers"
Peter James Walker and Michael Peter Albinson

Read More