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cafe latte 22nd June 2012 07:45 AM

Esl 57 Restoration
I am posting on VE my restoration of my Quads, I thought it may also be of intrest here. I am trying to explain every step and taking lots of pics.
Hope you find it interesting :)
Turntable Forum • ESL57 restoration finally started!

geraldfryjr 22nd June 2012 10:05 AM

Great Pic's,Thanks for Posting !!!
I like your method of stretching the Mylar.
I will have to give it a try !!!


jer :)

cafe latte 22nd June 2012 12:29 PM


Originally Posted by geraldfryjr (
Great Pic's,Thanks for Posting !!!
I like your method of stretching the Mylar.
I will have to give it a try !!!


jer :)

Not mine it is Rob from ER Audio who recommends it but I will say that I thought about a similar method when I first thought about doing up Quads (Years ago) but dismissed it as I always thought as the stators were curved it could not be done, I thought that if it were this easy others would be doing it... I reasoned that a jig allowed a bit of stretch for the curved stator, but when you strip a Quad you realise that the curved stator can be pressed flat for gluing. I read years ago on the net about the jig frames that people were building and thought there must be a good reason to go to all that trouble. Messing about building a jig is why I did not do this resto a long time ago. Also doing it the way I have makes sure the diaphrams are all equally tight and it is easy too. I took the first dust cover off the table tonight and it was perfect too done in the same way as the diaphram.
I will tighten the bolts tomorrow and maybe connect the stator in the evening and hopefully it will work.:D
Worried but a bit excited too.

geraldfryjr 22nd June 2012 01:18 PM

I do use almost the same method but I don't use a scale.

I lay the mylar down on some glass wetted with some denatured alcohol and rub it out so it is smooth, and, when I tape the edges I pull just enough to insure the wrinkles are gone.

Then when the frames are mounted I hit it lightly with a heat gun.
I have done this so many times I get nearly the same resonance every time, At least right within a narrow bandwidth of 70Hz to about 90Hz.

jer :)

lcsaszar 22nd June 2012 02:10 PM

Jer, do you mean the dust covers or also the diaphragm? I replaced the torn dust covers on my units, but not the diaphragm yet. I realized that too much stretching would bring up the resonance frequency, so I glued the mylar to the frames without stretching, and used a hair drier until the wrinkles disappeared. Could the same method (i. e. no stretching before glueing, stretching after glueing with hot air) applied to the diaphragm, as well?

geraldfryjr 22nd June 2012 02:55 PM

No, I was referring to just the diagphram,
I don't use dust covers on my own designs.
Your method is basically the same as mine,oshifis.

My mylar has some permanent creases in it so I just tension it enough so that they are gone.

If I happened to have a section that is completely flat then I just rub out all of the air bubbles and wrinkles so that it is as flat as the glass.
Then I tape it down the edges and plop on the glued frame and weight it down with another piece of glass on top of it, and wait for the epoxy to set.

jer :)

a.wayne 22nd June 2012 03:40 PM

Too much tension will be an issue , I prefer the blow dryer method for removing wrinkles ...

cafe latte 23rd June 2012 06:46 AM

Just tested the first unit and it is flat and very down on output so I may have to have another go, but I am not sure what went wrong. This stator was always low and it was one that was replaced by quad in the 80s but not it seems worse. Could it be I ned to give the soulble nilon longer to cure?
I also have a hiss from the bottom of the panel and a few ticks along the screws that run down the center of the panel, but no visable external arcing. The two strips that run down the panel inside (center) have what looks like paint on them but from menory they measure about 1,1k so they are not perfectly insulated.
If I have to do it again it is a pain but I would like to know were I am going wrong.
Any thoughts

geraldfryjr 23rd June 2012 10:51 AM

Hisses and ticks mean the the stators are leaking some.
Ticks would most likely be an arc, and, the hissing could be just a slight corona discharge that you may not be able to see at all.

jer :)

cafe latte 23rd June 2012 11:44 AM

I have pulled the panel apart ( not a problem as not it has not and bolts) and apart the foil strip along the bottom being VERY close to the bolts I cant see any issues. I will cut the strip slightly tomorrow away from the holes were the bolts pass and I have already wiped the diaphram with more conductive solution as IMO spraying it it was not even and smooth. I will also ensure the film is not able to touch any of the bolts.
If anyone has any other ideas please post as I am thinking on my feet and am far from an expery on ESL'S.

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