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Thank you for your answer.
Can I ask, what causes the high-pass crossover to fry, and how often would you say this problem occurs in the overall picture ?

Read the thread that JonFo has provided the link to and you will see how similar the problem this owner had is to yours and it sounds like your speakers are about the same age too, and like I said I hope I’m wrong about this. Because those speakers problems were with defective parts in the crossovers.
It's very odd for one speaker, then almost immediately the other, to fail. If you have a multimeter, check for DC on the speaker terminals of your amplifier with speakers disconnected and no input signal. The reading should be a few millivolts at most. Something external to the speakers that affected both of them must have happened. A large DC offset affecting both channels is one possibility.

A dead HV bias supply in the speaker could cause the sound, if any emerged at all, to be highly distorted. But it's almost inconceivable they could have both failed within minutes of each other. And I don't see how anything feeding the speakers could cause that.

I'm unfamiliar with the ESL 9, but apparently it uses some kind of external wall wart type power supply. It's possible a spike in the house AC line damaged both of them at once. That should be a cheap fix, at any rate. People here say the crossover is passive and I assume that goes for the woofer. It's hard to speculate on what inside the speaker could cause your symptoms. Bad step-up? Maybe, but again, it's hard to see what could have caused them both to fry at once, assuming the listening level was below the threshold of pain. DC offset is all I've got.
Hi guys.
I am the member who posted the level difference esl 9 speakers post.

I have a pair of these and have been through something similar.

Do let me know can I help ? I'm just going to read through all the threads and respond in linebut long story short.. write to ML USA immediately and they should align your local distributor. Else find your ML distributor in your country and write to them (not dealer or store, but you can copy them)

I fear something has caused either both your bias boards to fry. And this means panel damage is definite. I had both my panels and bias boards replaced after complaining. Since then my speakers have been fine. I have changed my amplifiers and upstream completely.

Let me quickly read this and come back with more technical suggestions if I can think of any.
First of all, I want to thank you, for your time and for sharing your insight.

I have checked the binding jumpers and they were tightend correctly, so loose jumpers are not causing any problems.

I removed the binding jumpers and conected the amp. to "only the woofer".
The left and the right woofer deliver the same, both volume and sound quality.

I then conceted the amp. to "only the ESL panel".
The left panel is for the most part close to normal(I think), I can hear some distortion, the higher tones are breaking up, just a little, even when the volume is low.

The right panel on very low and low volume dont`t get the ESL panel responding, I have to apply quite a bit, to get the right speaker to react. But then, the sound comes in very poor quality, it sounds nothing like it used to. and way worse than the left panel.

If you want me to try something else here, I will be happy to do it.

Hey Espen

I'm the member who posted the level difference post. I have read all the comments here and what you are going through. And basis my experience, here is my immediate summary of what might have happened and what is the solution.

1. The classe Amp you are using is a high current Amp. My speakers fried when I was using a emotiva amplifier and I cannot stress enough that these speakers do not live well with the wrong Amp. It's not the power or the brand, firstly high current amplifiers are not recommended for esl speakers. I have had ML and emotiva both send me emails against using these

2. After I had this problem, and maybe mine was quality related, the ML distributor here in my country India did replace both my panels and bias boards under warranty. My bias board had leaked and fried and that could have also affected my panels. So they changed both. The bias board is what charges the panel and if that is not functioning well the panels will do this and panels can get damaged. You are probably only seeing the symptom of the boards at the moment. Yes both can fry together if the amp sent something upstream.

3. I changed my upstream amplifiers to mcintosh monoblocks after my panels were fixed. I invested in a spec that has auto formers to be able to handle the impedence swings these speakers have. They need, NEED, amplifiers that are rated down to 2ohms to be able to survive. ML may say any amp works and it may but a high current amplifier is definitely a NO NO.

4. What has possibly happened is that your Amp for whatever scenario or reason as sent a signal or volume or a peak spike to both speakers at one time or over time that has fried your boards or since you use these less your boards have fried and deteriorated over time. The boards have capacitors that can leak. If you open the base of your speaker with home tools it will come out easily and gently and you can send us a picture of the bias board. See my post and the pictures I sent. If these boards are damaged you need new boards at the minimum. These maybe least expensive and may fix all problems.

5. If the boards have sent anything funky into then panels then the panels may also need replacement.

You need to contact the ML distributor in your country and ML USA with this case and let them comment. Find your countries ML distributor if there is one. Else email ML USA, they will align the right store or dealer to handle this and diagnose the problem.

I know this sounds like a pain but this is going to take a few weeks so be patient. Once they diagnose the boards crossovers they will know what to do next. Then it's about why and if these have warranty in your country beyond year 2. Else you may end up having to pay for new parts.

Remember the board or the panel can spoil each other as per what I have learnt but a sound output problem like this means your panels are not getting the charge they need. This means the bias boards. If your dealer or distributor has spare or can swap boards out with another set to try this problem will be confirmed.

I hope this sheds some light on this for you. Please connect with me if you need any further information.

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