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Hissing from Quad 63s - reason?

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I have a pair of ESL 63s and one has developed a hissing sound originating from the bottom left hand corner as you look from the front.
It doesn't do it all the time, although I've not been able to establish a pattern for when it does do it. Could it be due to increasing temperatures as summer approaches, or am I looking at a likely service issue (they were last fully serviced in July 2002)?
Many thanks,
-dex

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Re: Hissing from Quad 63s - reason? - stickler to perfection 20:37:55 04/17/07 (1)
The problem with the panel you described is that it has become defective. It was caused by either stator delamination or diaphragm
damage or both. The problem with 63 diaphragms over the years is that
that they lose their tension caused by either partial rupture or by
glue release at the edges where they are glued to the supporting
frame. The 63 diaphragms are very fatigue prone.
Your only remedy will be to have this panel repaired or replaced it with a new one. I would prefer the latter. High humidity would not matter then. It is not causing problems such as you described, it only makes an existing problem more noticeable.
Regards,
David
- Re: Hissing from Quad 63s - reason? - kentaja@yahoo.com 13:33:49 04/18/07 (0)
  Not necessarily. Noise under high humidity does not always mean a panel has gone south. If it did, I would conclude that virtually every panel Quad produces is defective.
  I have brand new Quad produced panels that under high humidity will start to make noise. And I have yet to find a Quad, the new ones, that given enough humidity don't make some noise. These are brand new Quad speakers. Get the humidity high enough with the original ESL and the bass panels will start to make some noise as well. Not nearly as bad as the ESL63, but the faint noise of excessive leakage is there.
  The glue failure, stator delamination problems you mention, yes, are very common problems with this design. When this happens the problem will be quite evident independent of humidity.
  The only question really is what is too much humidity? To get the original ESL bass panels to make some noise the humidity will need to generally be 80-90%. With the newer design, noise can start as low as 60% but generally is not a problem until the RH hits 70% and higher.
  Late generation ESL63 and the current speakers employ a varistor on the EHT board to reduce the available voltage to the panels as leakage/current demands become too high under humidity. The EHT board on the ESL63 went thru several revisions over the years to control excess leakage of the panel.
  If the speakers are making hissing noise get the humidity down. If the noise is gone and the speaker will produce 95-100dB levels prior to shut-down the panels are fine.
  Of course if the humidity is already low and the panels are hissing, then yes, it is time to replace a panel(s). Stator delamination or excessive oxidation of the conductive coating will generally be the problem. I have, unfortunately, pulled part panels that appear to have no problem at all, i.e. glue is intact all around, not a hint of oxidation or damage to the coating, and the things hiss. This speaker can be finicky in the extreme at times.
  Given the wide production variation of Quad panels, this noise/humidity issue is a moving target and some panels do better than others. Just like some panels will play considerably louder before the the charge starts to migrate and the speaker shuts down. Tight unit-to-unit consistency of the panels is not a hallmark of Quad even today.
Re: Hissing from Quad 63s - reason? - kentaja@yahoo.com 10:26:18 04/16/07 (5)
You have identified the most likely problem. High humidity conditions will make the 63 panels produce some hiss. The higher the humidity, the worse the hiss. High temps alone will not produce hiss. This does vary quit a bit from speaker-to-speaker. Some are worse than others. When the humidity drops, the hiss should disappear.
Generally the hiss will come from the ends of the panel where the conductive coating stops on the film. This is the typical leak point. As the humidity goes higher and the hiss becomes worse, it will sound like the entire panel(s) is hissing. The hiss is audible evidence of excessive panel leakage.
Try to keep your RH levels below 60%. This should stop the hissing.
This is not hard to do for most folks. Cold winters and forced air heat will keep inside RH levels well below 60% even with a humidifier is most cases. And high summer heat and central AC will generally keep the RH levels low enough as well. Spring and fall can be tough with more precipitation and the tendency to want to throw open the windows!
- Re: Hissing from Quad 63s - reason? - arend-jan 14:16:47 04/16/07 (4)
  Generally the hiss will come from the ends of the panel where the conductive coating stops on the film. This is the typical leak point.
  Anything that can be done about this besides lowering the humidity? I mean is it normal operation for this speaker to behave like that? I never had any trouble with my 63s but maybe humidity is not so high here, I don't know.
  - Re: Hissing from Quad 63s - reason? - kentaja@yahoo.com 15:18:51 04/16/07 (3)
    I would consider this normal behaviour for the ESL63. It does vary considerably depending on the particular speaker, but get the humidity high enough and they will all make some hissing noise.
    Sometimes the noise is low enough that unless you have your head against the speaker you will not hear the noise. Other times it will be noisy from across the room. Again, unit-to-unit variations.
    High humidity and stats are not a good combination. Some stats do better than others. The ESL63 would not be one of the better candidates IMO for high humidity environments.
    Late versions ESL63 Monitor and the newer 98/05 series of speakers do have some enhancements in the power supply to keep excess leakage under control in high humidity environments. But again, beyond a certain point, even this will not help.
    60% RH is very high and most people would find this level uncomfortable. I would be one. When I test ESL63 in my humidity chamber it is very uncomfortable. Test levels are generally 60-70% RH. I feel like I am just dripping!
    60% RH maximum levels is just an average. It is the point where I hear some, but not all ESL63 start to make noise.
    - Re: Hissing from Quad 63s - reason? - arend-jan 02:07:34 04/18/07 (1)
      Hi, thanks for the info.
      You say Late versions ESL63 Monitor and the newer 98/05 series of speakers do have some enhancements in the power supply to keep excess leakage under control
      Do you know what kind of enhancements that might be? Perhaps lowering the HT? I know the 57 had a lower voltage tap (590 vs 610) on the HT transformer probably for situations like this.
      It makes me wonder what factors might control this behavior when you say it varies from unit to unit.
      - Re: Hissing from Quad 63s - reason? - kentaja@yahoo.com 14:07:40 04/18/07 (0)
        
        In Reply to: Re: Hissing from Quad 63s - reason? posted by arend-jan on April 18, 2007 at 02:07:34:
        
        I can only speculate as to the exact reasons why. The nature of the stator design itself, wide variation on the carbon coating, extremely low surface resistance for a full range stat(the mostely likely cause IMO). Every potential solution to a given problem creates a new and different problem.
        If one could nail down the exact cause, and the exact solution, I am sure Quad would like to know as well. To quote Ross Walker "But of course it was such a mystery....nobody every understood - I don't think we quite know to this day why the plates 'tick', do we?(Laughs)." May 2003
        "....was the most diabolical bit of product engineering you've ever come across. The failure rates?(Laughs.) Depended on whether is was a Monday or a Wednesday and it was wet and all the rest of it - a complete nightmare." Ross Walker - May 2003
        "I don't think we made a penny on the '63. Optimistically, when we were doing '63s, we had between 10 and 12 man-hours of labour in the bloody thing......" "If every one had only 10 man-hours of labour in it, it would have been fine. But it was our fault that they were rebuilt twice before they even got out of the bloody factory." Ross Walker - May 2003
        What is the rebuild Ross is referring too? The panels. The electronics would have been a piece of cake for a company like Quad. If was the inability to consistently build the panels.
        I would love to know what the actual panel drop rate is on the production floor. One day the process works; you do it the same way the next day and the panels don't work. They make noise, excessive charge migration, varying sensitivity.
        I doubt things have changed much with the Chinese produced speakers. The panels are built today exactly like they were 20 years ago. There is absolutely no change whatsoever to the panel itself. With cheaper labor and higher retail prices, Quad can make some money on them, something they never were able to do when the Walker's owned the company. The panels are difficult in the extreme to produce.
    - Re: Hissing from Quad 63s - reason? - copydex 00:27:58 04/17/07 (0)
      Thanks for the very informative reply.
      It makes sense to me as they still sound absolutely glorious, even when the hissing is present, so I would have been surprised if they needed servicing again so soon. I hope to get a few more years service free use before I send them away to be done again.
      Long live (my!) ESLs!
      -dex

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