Quad ESL 57 panel refurbish: DIY or not?
Since about 10 days I am a happy owner of two Quad ESL 57 loudspeakers in very good optical condition (including dust covers).
Serial numbers 30509 and 30510!
I replaced the diodes in the HV supply in both panels .
One speaker is now working very good considering its age: 38 years.
The other speaker has one bass panel not playing. The second bass panel of this speaker is very low in level.
I will investigate further.
Here a picture of both panels on new stands (not finished, one panel still has the original feets attached and the "old" horn speakers are still ready for backup...)
When I now decide to use this speakers for the rest of my life, I have to make the decision:
Should I save money to let refurbish the panels by Quad Musikwiedergabe in Germany? They use the original equipment to do this job.
Or should I learn to refurbish ESL panels? Build a rig and all this stuff?
Will I have a stable and consistent result from my diy work? Will it be worth all the effort?
@Calvin: did you receive my two mails from oct 13th and 14th, about replacing the diodes? It was the first step for me, to really be in contact with the innerts of this speakers, believe me!
BTW: I drive the ESL 57 actually by an F5, it seems to be an ideal amplifier for this speakers. I will later compare the F5 as driver with the two Quad II monoblocks I also own.
And the ESL's are supported by a professional JBL 350W subwoofer (the black box behind the left panel).
DIY Quad ESL rebuild
I have had good results with DIY rebuilds on Quad ESL's.
There are several companies that sell good all in one panel rebuild kits, as well as parts; or you could probably source them on your own.
There is many Quad ESL DIY websites, which you probably are aware of.
IMO - the best company I've delt with in the past 10 years for repair kits is ER Audio in Australia. They sell a complete rebuild kit and have great support, but they don't use the exact same materials that Quad did 40+ years ago.
My experience is that the bass panels seldom fail. They might not get the 6 kV polarizing voltage, or there is a loosy terminal-to-diaphragm contact.
I permanently connected small wire lead neon bulbs in series with the polarizing voltages on the PSU block (both on 1.5 kV for the treble and on the 6 kV for the bass - the latter could be done separately to each bass panel) so I can visually detect any leakage as neon light blinking.
Yes, I also plan to install blinkers to control leakage.
My intention was to use the same circuit as used in the ESL 63: a bulb with a cap in parallel and inserting a protection resistor.
What type of neon bulbs do you use?
I agree: it is hard to believe, that the bass panel failed.
I will investigate further.
One bass panel of this speaker is playing on low level, the other is silent.
Most likely a problem with the connecting wires-or failure of one of the resistors.
I replaced also the two resistors by new ones and double checked the wiring and soldering points.
It is hard to believe, something should be failed in this panel, when I look the nearby mint condition:
But, there is an UFO inside the dustcovers:
I will now take the HT-supply out of the working speaker and test the faulty speaker with this HT-supply.
You could at least try to re-insulate everything: unsolder panels, remove dustcovers, replace tape on the edges (which go over rivets).
In my experience, the diaphragms themselves rarely fail, but the coating on them is often gone or marginal. The soluable nylon they used as a conductive coating wasn't particularly good and dissipates over the years. I've seen many bass panels where the bottom half charges and the top doesn't.
I also second the recommendation on the ER audio kits.
Since you already tore into the 57's and seem to know the layout pretty well, it would be best to do the complete panel rebuilds now and save time and effort of putting them back together and breaking them down every time you hear an issue...
Sheldon (stokessed) is the man (IMO) when it comes to Quad ESL's, so take his advice as word.
I don't have any association with him, but have owned Quads that he rebuilt the panels, and his work was top notch.
Once you get the panels completely rebuilt, you will not have to worry about them for years, unless you get too crazy with the power amps.
The neon light circuit adapted from the 63's sound like a great idea too.
BUT: there is also a financial aspect.
I could refurbish both Quad II amplifiers I own, sale it and use the income to refurbish the speakers.
BUT: I also want to compare the Quad II to my F5...
I am also aware, that I have to take the advice from Sheldon as an expert advice.
Thanks for all advices up to now in this thread, Guys!
And still: I am a DIYselfer and I try to find the fault. Maybe it encourages me to do panel rebuilds by myself.
Another good contact is Jan-Arend, I heard his Quad ESL57 at the ETF 08 and they are very good.
At the moment I am listening to Roger Waters "The pros and cons of Hitchiking" from Vinyl, Eric Clapton on Guitar, Salas RIAA pre, F5, 5/6 Quad ESL: Great! I will stick with this ESL for a long time, I am sure!
Any idea from where the UFO could origin? Some small ring, obviously made from metal.
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