A few (5 or 6) years ago, I bought my third pair of the Quad ESL57 and they stayed in the box unopened until a couple of weeks ago. The last owner sold them because he claimed that one of the speakers was not playing as loudly as the other! He had not bothered to have them looked at since he had already moved to a smaller apartment and enough space was not available for these speakers.
Since then, my first pair of my ESL57 (did not have any problems) got sold last year and then I repaired the second pair that had a leaking treble panel that caused low sound output even after the EHT power supply was refurbished. So I am quite familiar and openly grateful for the information provided by Sheldon Stokes, Keith Snook and others.
Hence we come to the problem at hand, and I will describe it as best as possible: I unboxed only one of the speakers and connected it to my system, hoping to compare it against a system that was already there and working well over a long period of time. Very slowly, it came back to life and played the way I think it should! The speaker looks like new, no dents on the shiny front grille, an extremely well preserved item whose serial number dates it back to 1967! I left it unplugged overnight. Next morning, coffee cup in hand, 20 or so screws later the back cover with the horse hair comes off….I am looking inside at pristine speaker panels with hardly any dust and original 1972 dated repairable EHT power supply and original audio transformer components. I try to measure the EHT with a normal Digital Voltmeter and the treble voltage goes overload and the bass EHT barks back with a crisp spark before I can even touch the terminal! I put the back cover on again and test it…..all is well. Still shaken, I order a High Voltage probe.
Next, I unboxed the second speaker and it too plays as well and equally loudly after charging up! The next day, I open it up and it too seems all like new inside. The only difference being that there is the very old epoxy version of EHT power supply that cannot be refurbished.
I cannot figure out if there is a problem with them, except when I power them off whilst still playing….The speaker with the old epoxy EHT power supply begins to play more faintly after 3 or 4 minutes compared to the other.
Considering the fact that both speakers do not show their real age, I am presuming that they were completely refurbished but I fail to understand why anybody would put the obsolete EHT power supply on such an undertaking where even the Bulgin mains plugs look new!
Does anybody know if the obsolete EHT supplies less EHT voltage compared to the newer ones?
Any help or suggestions will be greatly appreciated.
Since then, my first pair of my ESL57 (did not have any problems) got sold last year and then I repaired the second pair that had a leaking treble panel that caused low sound output even after the EHT power supply was refurbished. So I am quite familiar and openly grateful for the information provided by Sheldon Stokes, Keith Snook and others.
Hence we come to the problem at hand, and I will describe it as best as possible: I unboxed only one of the speakers and connected it to my system, hoping to compare it against a system that was already there and working well over a long period of time. Very slowly, it came back to life and played the way I think it should! The speaker looks like new, no dents on the shiny front grille, an extremely well preserved item whose serial number dates it back to 1967! I left it unplugged overnight. Next morning, coffee cup in hand, 20 or so screws later the back cover with the horse hair comes off….I am looking inside at pristine speaker panels with hardly any dust and original 1972 dated repairable EHT power supply and original audio transformer components. I try to measure the EHT with a normal Digital Voltmeter and the treble voltage goes overload and the bass EHT barks back with a crisp spark before I can even touch the terminal! I put the back cover on again and test it…..all is well. Still shaken, I order a High Voltage probe.
Next, I unboxed the second speaker and it too plays as well and equally loudly after charging up! The next day, I open it up and it too seems all like new inside. The only difference being that there is the very old epoxy version of EHT power supply that cannot be refurbished.
I cannot figure out if there is a problem with them, except when I power them off whilst still playing….The speaker with the old epoxy EHT power supply begins to play more faintly after 3 or 4 minutes compared to the other.
Considering the fact that both speakers do not show their real age, I am presuming that they were completely refurbished but I fail to understand why anybody would put the obsolete EHT power supply on such an undertaking where even the Bulgin mains plugs look new!
Does anybody know if the obsolete EHT supplies less EHT voltage compared to the newer ones?
Any help or suggestions will be greatly appreciated.
I believe that the epoxy EHT is the same inside as the later beeswax versions. The fact that both play the same is a good sign, and indicates that the EHT's are probably fine (the odds of both being exactly the same level of badness is pretty unlikely). The fact that one speaker dies sooner than the other can be a couple of factors, and not necessarily a problem.
1) the epoxy speaker EHT module could just be starting to go bad, and is a touch more leaky than the other. The epoxy itself may be more conductive than the bees wax and the module is perfectly fine. I've never tested that theory, but it's very possible.
2) More likely is that the panels in the epoxy speaker are just a touch more leaky than the other speaker. These panels are not made with the level of care that you might like or expect, and it's very possible that one is slightly contaminated and drawing a touch more HV current than it should. We are talking about a tiny amount though, so not to worry.
I would suggest that as long as they are working, and sound good and the levels are well matched, that you don't do anything.
Actually I take that back, you may want to add the quad based treble panel clamp circuit to the speakers so you won't have to give me your money in the future.
Sheldon
1) the epoxy speaker EHT module could just be starting to go bad, and is a touch more leaky than the other. The epoxy itself may be more conductive than the bees wax and the module is perfectly fine. I've never tested that theory, but it's very possible.
2) More likely is that the panels in the epoxy speaker are just a touch more leaky than the other speaker. These panels are not made with the level of care that you might like or expect, and it's very possible that one is slightly contaminated and drawing a touch more HV current than it should. We are talking about a tiny amount though, so not to worry.
I would suggest that as long as they are working, and sound good and the levels are well matched, that you don't do anything.
Actually I take that back, you may want to add the quad based treble panel clamp circuit to the speakers so you won't have to give me your money in the future.
Sheldon
A big hug from Portugal for you Sheldon, your book and Keith Snook´s info gave me that all important final push to find my wings!
I have already ordered a used power supply that can be refurbished with the twin diodes and capacitors as well as one treble panel for my stock of good parts that already includes 2 bass panels.
My second pair of ESL 57s already include the GDT that you used to recommend so I feel a bit more protected when using them.
Since this 3rd pair is so good visually and has all the original components, I will probably try to manually build your EHT supply with the 2 neon lamps to test the panels as well as eliminate the old epoxy EHT from the equation by refurbishing the used power supply bought recently. Someone commented that the since the neon lamps directly charge the panels and hence display its health by the frequency at which they flash, the sound is somehow affected but for the better!
Also, I have a feeling that it would be much easier to sell this lovely looking pair rather than my 2nd all updated but ragged looking pair. The little lady here has declared war on all of my hifi collection, so I am only allowed to keep 2 complete systems however big or ugly or old! She is of course right because I have 5 complete systems!
I have already ordered a used power supply that can be refurbished with the twin diodes and capacitors as well as one treble panel for my stock of good parts that already includes 2 bass panels.
My second pair of ESL 57s already include the GDT that you used to recommend so I feel a bit more protected when using them.
Since this 3rd pair is so good visually and has all the original components, I will probably try to manually build your EHT supply with the 2 neon lamps to test the panels as well as eliminate the old epoxy EHT from the equation by refurbishing the used power supply bought recently. Someone commented that the since the neon lamps directly charge the panels and hence display its health by the frequency at which they flash, the sound is somehow affected but for the better!
Also, I have a feeling that it would be much easier to sell this lovely looking pair rather than my 2nd all updated but ragged looking pair. The little lady here has declared war on all of my hifi collection, so I am only allowed to keep 2 complete systems however big or ugly or old! She is of course right because I have 5 complete systems!