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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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Aurealis Audio

 A Great 
 Cable

Aura Turntable

The Aura

A Great Turntable

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
  • 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
  • Top Components >

    There are very few components that I would unreservedly trust to put in my own Quads. Pre-built components, that is. 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 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

Read More

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

Read More

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

Read More

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

Read More

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

Read More

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.

Read More

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

Read More

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

Read More

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

Read More

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

Read More

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

Read More

Gang of Five

Gary Jacobson

N.B. This article is about 10 years old. Therefore an historical document!

Any advice and observations that it contains should therefore NOT be taken as being, in any way current.

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

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.

Read More

 

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.

Read More

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

Read More

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

Read More

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

Read More

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

Read More

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

Read More

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

Read More

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

Read More

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

Read More

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.

Read More

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.

Read More

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.

Read More

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.

Read More

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.

Read More

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

Read More

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

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

Read More

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.

Read More

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

Before attempting any repair or restoration work on the Bass Panels, you need to determine if there is actually anything wrong with them. Damage to dust covers will usually be obvious, or the dust covers will be starting to become very “brittle” to the touch. If so, replace the dust covers, at least...see Dust Covers.

Otherwise, life can be tricky with bass panels. The bass panels never show arcing damage, as treble panels do. They suffer from excessive leakage to the frame, and via the rivets. They also lose their diaphragm coating over a period of about 10 to 15 years. If the diaphragm coating is partly or mainly(!) missing then the bass output will be significantly down on the output of a factory fresh panel. This is one reason why, I suspect, that people who listen to aged Quads notice that "lack of bass" that everyone writes about when reviewing the Quads. A lot of this palaver is sometimes about a panel which is well out of specification. A simple series of tests to determine if the bass panel is leaky is described in the EHT Fixit section of this site. Alas, the only really definitive way to determine if the bass panel coating has seen better days is to pull the panel apart. If you do this, then you may as well replace the diaphragm while you're at it.

 

Materials and Tools:

o Fine Sand Paper (600 grit and finer)
o Silver Loaded Paint
o Gray Enamel Paint
o High Voltage Wire
o Solder & Soldering Iron(s)
o Dust Cover Shrink Film
o PVC Tape (2")
o Aluminium Tape/Foil
o Mylar® or other suitable 12 mm polyester film
o Isopropyl Alcohol and/or Acetone
o Corona Lacquer or Circuit Board Lacquer
o Diaphragm Coating Material (CALATON CB, ELVAMIDE, DIY soluble nylon, graphite; et cetera)
o Screw Drivers (Flat blade & Philips)
o 60 x 12mm x 3mm machine bolts
o 60 x 3mm Hex nuts for bolts
o 120 x 3mm washers for each side of panel
o Hobby Knife
o Masking Tape

N.B. I have described a coating method below using graphite, but it is not the best coating to use, by far. Soluble nylon is the original coating, and I believe, the best for this speaker. You can buy soluble nylon in Area 51 on this site, if you wish, and that purchase will also help keep this site on-line.

 

Stators & Dust Covers
 

  1. Physically disconnect and remove the panel from the speaker. This procedure is described in the Disassembly Section, and this section should be read, and well understood, before attempting to remove any panels from the speaker. With the panel now removed, you can (almost) see the structure . It is a five layer composite. The two obvious outer layers are the dust covers. The next two (still obvious) layers are the perforated stators. The centre-most layer is the diaphragm - not obvious, you cannot see it at this point. The actual bass panel looks like this , except that it will have clear tape holding the dust covers on, not gray PVC tape.
     
  2. Remove the dust covers by carefully slitting the tape around the periphery of the panel. Keep a vacuum cleaner handy, you'll generate a lot of dust here with old panels! Be careful not to cut into the stators, they're only plastic; or, indeed, the wooden frames as these are very light wood. N.B. To completely remove the dust covers, you will need to also de-solder the three thick (white, red, black) wires from the small phenolic connection board at the bottom of the panel. Put the dust covers aside for replacement separately. You can now clearly appreciate the physical state of the panels. There will probably be spots of missing gray paint. Spots of missing stator coating (conductive coating is on the outside of bass stators). Spots of “corrosion” around the rivets. [Example Picture ] You can also clearly see that the bass panel is held together with about 60 rivets - what a bastard! Why rivets? They are: 1) quick & easy to use, 2) don't present much sharp surface for corona to form, 3) are cheap and 4) allow a close fitting dust cover. They are also a complete bastard to remove!
     
  3. Remove the rivets holding the two stators together. This can be done by crimping the rivets in two directions at 90o to each other and pushing the rivet out. I use a high speed drill, like an Arlec Super Tooltm. A fair bit of heat is generated, and the stator will often soften slightly. I view this as somewhat of an advantage, if you don't overdo it(!). The rivet will push easily out through the original hole after a couple of seconds drilling with the appropriate abrasive head on the tool. I use a 3.5mm carborundum ball. The hole will be slightly enlarged, but this is not a problem, since we re-fasten with 3mm bolts and nuts, with washers. This operation is a pain in the bum, takes a long time, generates a lot of dust and dirt, and you need to clean the whole of each stator when finished, whichever method you use. Try not to knock off any more of the paint on the outside. If any white plastic is showing, then you will need to re-coat with conductive paint. More on that later.
     
  4. Once the rivets are removed, you need to de-solder the thick white wire that carries signal to the front stator from its solder tab. Use a heat sink on the tab, and a very hot soldering iron. Just heat the tab enough to pull the wire off the front, or you'll melt the stator for sure. Push the wire back through both stators to the rear, so that you can separate the two stators. The panel is now in two parts. One stator, and one stator with the diaphragm attached. The original diaphragm , if original, will have white, streaky marks all over it. This is a CALATON® coating used by Quad at the factory. The diaphragm can be removed, since you have decided to replace it.
     
  5. Carefully scrape, or sand off the remaining diaphragm material and glue at the edges of the stators. Use a fine paper, about 600 grit wet & dry is OK. Try not to make any deep scratches - anywhere!
     
  6. Thoroughly vacuum clean the stators so that all dust, paint, et cetera, is removed. You should now have a clean white bass stator, that looks a bit like this...
     
  7. Examine the stator structure thoroughly. A normal stator - carbon tracks and tapes - looks like this all around. The aluminium tape around the edges can be corroded. A typical cause of corrosion is absorbed water from the dust cover frame, in humid climates. The dust cover frames also, very occasionally, have had "sappy" wood in some places on the frame that absorbed extra moisture, helping to corrode the perimeter tape. If corrosion is present, it will be obvious as a white calcification, or white powder. This will tape need repair, if corrosion is present, as the tape is essential to charging the diaphragm.
     
  8. Clean any corroded tape areas with sand paper. You may find that the corrosion has eaten clean through the tape and you will need to scrape the area clean with a sharp knife (e.g. Hobby Knife, Stanley Knife). Be careful not to scrape the stator plastic too much. Wipe clean with alcohol, or mild soap and water.
     
  9. Bridge the gap with aluminium foil that is affixed to the plastic with conductive paint (see Parts Section ). The conductive paint will provide a small amount of adhesion to hold the foil in place. Use two layers of foil in all. When the stators are re-attached to each other the foils will be firmly held to the diaphragm, and the conductive paint will put put to rest any worry of discontinuity that the use of glues might bring up. A repaired stator tape looks something like this...
     
  10. Examine the outer surfaces of the bass panels. If there is any white plastic showing through, then both the conductive paint layer and the gray paint layer have been lost (somehow). A typical panel in need of this sort of repair is shown here .
     
  11. Repair this type of problem, or where white plastic shows through, by gently cleaning loose material away with very fine sand paper (600 grit or finer) and then re-painting (firstly) with conductive paint (See Parts Section) and then covering with a gray finish. The gray paint is there to stop the panel reflecting too much light back through the grille, and it really doesn't matter if the gray doesn't match. You could re-paint the whole stator for a nice, cosmetic effect, if you like, but be careful that you NEVER allow paint of either sort to drool into those perforations!!! N.B. There is one exception to this rule. Around the rivets, simply sand back, and re-paint with gray paint only. Extending the conductive paint to the rivets will only increase (or create!) panel leakage.

 

Diaphragm Replacement 


OK, you've got this far, and you're feeling pretty pleased with yourself. Let's see what we can do about that, then!! By this stage you should have two clean, repaired stators, with no tape breaks, corrosion, or conductive layer discontinuities.

  1. Cut a piece of 12 mm Mylar which is about 10 cm larger than the bass panel stator in each dimension.
     
  2. Clean a smooth laminex or glass topped table with ordinary household detergent. Dry well, and then clean with either isopropyl alcohol or acetone. N.B. Both of these materials are flammable. Acetone in particular!! Do not allow anyone to smoke or bring a naked flame into the same HOUSE with acetone. Both materials are relatively innocuous, otherwise. Your objective here is to remove anything of a lumpy, or gritty nature from the work area.
     
  3. Lay out the diaphragm film smoothly on the table top, and fix the corners with masking tape, stretching the film slightly as you do this. Then attach masking tape to the centres of each side, stretching the Mylar ® again, in each direction. Continue taping each side by "splitting the difference" between previous tape points, until you have the Mylar® reasonably taught. Don't try to get it very tight at this point, but do tape it firmly all around.
     
  4. Using the inner stator dimensions as a guide, mark, or mask off, a rectangle to be coated.
     
  5. If using graphite (not recommended), rub the powdered graphite into the Mylar® as hard as you can. Try to really grind it in, and get a uniform coating. Test the surface for uniform conductivity with a surface resistivity meter or DVM that can read to at least 100 MW . This will produce a diaphragm which is far too low in resistance to be really useful in a Quad Electrostatic. Don't panic!! N.B. Soluble NYLON is the best coating to use, and it just wipes on in alcohol solution.
     
  6. Try to rub off all the graphite, using a paper towel soaked in isopropyl alcohol. A graphite glaze will be produced, and the colour of the diaphragm will appear a very light gray. Do try to rub off all the graphite. IF you ground it into the film well enough, it won't come off completely.
     
  7. Check the resistance with your meter. If it is not at least 100 MW then try rubbing the graphite off a little more. You also need to avoid making large discontinuities in the membrane coating. This is why this method is such a pain, even if the process is, practically speaking, very simple. When the membrane measures as you would like it, clean the general surroundings, but leave the Mylar® taped to the table top.
     
  8. If you want to avoid this rubbing and grunting and carrying on, just wipe on some DIY soluble nylon, or CALATON CB, or ELVAMIDE any of which duplicate the original Quad diaphragm coating, and wait for it to dry off. Diaphragm coated - no effort.
     
  9. Mix up some two part epoxy resin glue - the PLAIN kind - no metal fillers!!
     
  10. Choose a stator to glue the membrane to.
     
  11. Apply a thin (1/8th inch) bead around the perimeter where the old brown glue was. Do not put epoxy on the metal tape. The bead should be run between the tape and the outer edge of the stator.
     
  12. Place the stator, glue side down(!) over the Mylar® film being very, very careful to align the inner rectangle of the stator with the coated area.
     
  13. Press down with both thumbs all around the perimeter of the stator where the bead of glue was run. The idea is to squeeze the glue into a very thin film. N.B. Placing weights on the stator at this time, alone, will not do a good enough job.
     
  14. Place a layer of books, a sheet of steel, or something solid, over the stator to spread the pressure, and weight the whole thing with bricks. Wait until the glue is well cured. I leave the stator overnight, usually, no matter which epoxy I use.
     
  15. When the glue is well cured, remove all the weights and other paraphernalia, and lift up the stator with diaphragm attached. Trim the edges very carefully with a very sharp knife, (e.g. Stanley Knife).
     
  16. Heat Shrink the diaphragm with a heat gun set at about 400 Watts, working about 20 to 30 cm from the diaphragm. There are so many variables involved in this, that it is impossible to give precise instructions. If you have not done this before, then you must practice with a spare piece of Mylar®. Tape a 20cm x 20cm piece of Mylar® film to a table top and practice heat shrinking until you can shrink the film tightly (no little creases) without melting a hole in the film! If you melt a hole in the diaphragm, then you can start again.
     
  17. Coat the exposed side of the diaphragm with DIY soluble Nylon if you are using the original coating. This is what Quad did both sides at the factory, and what you should do if you want the speaker restored to its original condition. See the FAQs for an explanation of why this is so.
     
  18. Melt holes in the diaphragm for each stator hole (60 holes) with a fine-pointed tip on a small wattage soldering iron.
     
  19. Double check that the heat shrink job is OK. If not, carefully heat shrink again. Leave overnight and repeat the heat shrinking if not sure. The diaphragm should be perfectly smooth, although this is not as critical as it is for treble panels.
     
  20. Using 12mm x 3mm (M3) bolts, hex nuts, and two washers (one each side), bolt the stators together. N.B. Do not forget to run the front stator high voltage wire back through the holes in each stator and re-solder it to the tab on the front stator. Tighten each nut and bolt firmly, but not too tight.
  21. Run a line of PVC tape around the perimeter of the panel, covering the outermost bolts. This is added insulation to prevent leakage to the frame. Everything conducts (it seems some times) at 6 000 Volts.
     
  22. Take the refurbished Dust Covers and identify the rear cover. This will need holes drilled in it to accommodate the hex nuts on the rear stator. Otherwise the panel, overall, will be thicker than the original and will not fit into the frame without other unpleasant maneuvering.
     
  23. Re-fit the small phenolic connection board to the bottom of the rear dust cover - it bolts to the bottom of the frame with two small (12mm x 2mm) bolts. You may have to re-drill one mounting hole to do this if the new framing arrangements overlap the original holes.
     
  24. Melt holes in the dust cover film to match the holes in the small board, and run the HT and signal wires through the appropriate holes. LEFT - REAR Stator (white). MIDDLE - EHT Connection (red). RIGHT - FRONT Stator (black). N.B. The older speakers have all white wires, so watch what you're doing!
     
  25. Tape the dust covers in a “sandwich” with the rebuilt panel between them using 2" PVC tape. Make sure there are no gaps, or there will be panel leakage somewhere.
     
  26. The panel is now ready to be refitted to the frame and the appropriate solder connections to the EHT and Audio transformer can be made now or later.

 

There are very few components that I would unreservedly trust to put in my own Quads.  Pre-built components, that is.

Here are three that you can use with complete confidence (available from Electrostatic Solutions (on eBay)

Standard EHT Board

When you drive the treble panels too hard -->> shit happens!