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Thread: Weak sounding panel repair (nothing to lose)

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    Member enilsen's Avatar
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    Default Weak sounding panel repair (nothing to lose)

    This might be the most significant repair that can be done to those weak sounding panels other than purchasing new elements. We can assume that the warranty has also run out by this time and you are left with no other options. There is no need to disassemble the speakers for this to work.

    I would however advise that you would at least have attempted to wash the panels once just in case there are contaminants on the surface. In any event you will have the satisfaction that they are clean and in fact weak in sound to the point that something is wrong and of course you didn’t forget to plug them in.

    Over the many years of use our panels start to loose their sparkle (weak in sound). I have been told by ML it has to do with the conductive coating failing and consequently the static charge that helps move the Mylar diaphragm doesn't retain enough charge to attract itself to the perforated stators on either side.

    After a lot of research and experimentation I have found that using a diluted solution of water and antibacterial liquid soap (brand name TERSASEPTIC) has successfully restored the weak sounding panels. You local pharmacy should have this in stock else I have also seen it on ebay (over priced).

    There are two typical areas of failure to be addressed. The primary point of failure is between the bias aluminium strip and the Mylar diaphragm. This can be found at the bottom of the speaker element hidden behind the non-perforated area. Its purpose is to conduct the static charge to the diaphragm. To restore this failing connection you will need to apply a small amount solution using a small eye dropper or a thin tube along the lower part of the perforated stator. Allow only a small amount of liquid to run down the diaphragm and meet the soft insulating rubber strip. Continue at even spaces about 1” apart until you cover the width of the speaker.

    As a precaution I recommend that you only try a small amount first to the left bottom corner and listen to the results. Needless to say if you experience the WOW factor you won't stop there.

    The second point of failure is the rest of the diaphragm. A simple hearing test will confirm if there are any weak sounding areas on the panel. This might not be obvious if the whole panel is bad so to determine if the static charge doesn't reach the rest of the panel we need to help things along.

    Take a standard RCA audio cable and insert the centre pin through one of the small holes at the base of the stator just touching the diaphragm (the centre pin should have a smooth surface). Now take the other end of the RCA cable and place the centre of that plug against any weak sounding part of the diaphragm (try to avoid resting the centre pin on the stator). Needless to say you should have music playing while doing this. The purpose of this is to transfer the static charge though the insulated cable. If the sound returns to that area of the panel then you know there is failing conductive coating. It should be noted you won’t get an electric shock from the static charge on the diaphragm (the stators on the other hand carry a punch).

    To restore sound to the rest of the panel or just sections just follow the procedure we used when using the small eye dropper or thin tube and allow the solution to run down the diaphragm to the bottom where the static bias charge originates. Take precaution not to use too much solution and do it in several stages.

    Initially the speakers will be very sensitive and require very little output from the amplifier to drive, but after 3 days the solution should have dried sufficiently to allow a more normal playing volume.

    The dilution ratio I used was about 50% as this particular liquid soap is rather thick (like syrup on pancakes). It shouldn't be too runny like water, but enough to retain its soapy consistence (like olive oil).
    Before applying any conductive liquids to the panels always do a simple test using Saran-wrap (Glad-wrap) plastic over a small dish and testing the solution after it dries. An inexpensive ohm meter will suit the purpose using 2 small coins placed at each end of the stretched plastic and measure the resistance created by the applied solution. If there is no resistance then the solution will not work.

    I can testify that this has restored my 19 year old CLS speakers for the last 30 months and would appear to be a permanent solution other than buying new elements. In fact I would claim that they have never sounded this good since the 80’s. I have waited with posting this tweak just in case it turned out to have a negative impact, but they are still going strong and can really play at volumes again.

    Hope this might be a useful fix when all else fails. There is no guaranty that this will work for all CLS speakers as through the years ML has obviously been aware of the problem and made changes to address these kinds of issues. Hence the option to purchase new panels.


    Alternative solution for weak sounding CLS panels

    How to test the quality of the conductive membrane?
     
    CLS production numbers #441 & #442 Classé CA-200 pwr-amp (SS) Audio Research SP8 pre-amp (tubes) Thorens 226 turntable

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    That sounds like a great idea! Teraseptic probably contains iodine, which if I remember correctly is conductive.
    GC Electronics makes two conductive paints, Silverprint and Nickelprint, which contain silver and nickel powder, respectively, but those couldn't be used on the diaphragms directly, because the acetone carrier solvent would eat the mylar. A possibility would be to remove the required stator and use that paint on the conductive strip at the bottom.
    Hope this helps!
    Regards,
    Ross

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    I presume this post is referring to the original CLS panels? without the side (bass) sections of the later panels?

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    Member enilsen's Avatar
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    Quote Originally Posted by Tube60
    That sounds like a great idea! Teraseptic probably contains iodine, which if I remember correctly is conductive.
    GC Electronics makes two conductive paints, Silverprint and Nickelprint, which contain silver and nickel powder, respectively, but those couldn't be used on the diaphragms directly, because the acetone carrier solvent would eat the mylar. A possibility would be to remove the required stator and use that paint on the conductive strip at the bottom.
    I'm not sure what the active ingredient is as there are quite a few chemicals in this liquid soap (no iodine). The point here is that there are many suitable substitutes out there which will work but can fail shortly after.
    The existing bias aluminium strip is a good conductor for the static charge. I don't think any conductive paint could work as a substitute for the reasons you describe. You have to remember we are dealing with static electricity and not an electric current in the traditional sense. Think of this way a balloon can be statically charged but not conduct a regular electric current. So we want our diaphragm to retain as much of a static charge all over else it won't work. The dried liquid soap is only acting as a medium to help transfer the static charge. The fact that it is slightly conductive makes it IMO a better substitute to transfer a static charge to the rest of the diaphragm.

    Quote Originally Posted by nsgarch
    I presume this post is referring to the original CLS panels? without the side (bass) sections of the later panels?
    The panels I did this on are the full-range CLS-I (the model between CLS original and CLS-II). I'm sure a few members here have owned or still own these. In some cases they might still be standing in livings-rooms as decoration or packed away and not even used anymore. These panels are almost identical to CLS-II and do have the side (bass) as used in newer panels. For years I lived in denial thinking that the sound from the top of the panels is supposed to be weak. How wrong I was.
    Last edited by enilsen; 10-12-2006 at 07:10 AM.
    CLS production numbers #441 & #442 Classé CA-200 pwr-amp (SS) Audio Research SP8 pre-amp (tubes) Thorens 226 turntable

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    Default Tweeks

    Antibacterial soap, great!
    Anyone have any thoughts about Pro gold as a substitute?
    It does a great job at ridding cables of tarnish and is an electrical contact enhancer.
    Would Pro Gold applied to the same areas and sprayed on or eye dropped on work even better?

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    Even if Pro Gold did a good job of restoring the connection to the bias strip the fluid properties of this application would never dry on the diaphragm. Hence dust and other contaminants could gather over time making it a bit of a mess.

    If you ever needed to wash or vacuum those panels in the future what would the Pro Gold be like? Hmm!

    The antibacterial liquid soap on the other hand would wash off and would need to be re-applied again. Not a big deal when you realize how little work is involved.

    Just out of curiosity you should try some Pro Gold using a simple test with Saran-wrap (Glad-wrap) plastic over a small dish and measure the resistance. If it doesn't conduct electricity then it is an insulator and could spoil you chances of restoring the connection.
    CLS production numbers #441 & #442 Classé CA-200 pwr-amp (SS) Audio Research SP8 pre-amp (tubes) Thorens 226 turntable

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    Default weak panel repair

    Pro gold evaporates and doesn't leave any goo,perhaps you are mistaking it for something else.
    I wonder more about what residue is left from the soap solution?
    Can anyone elaborate ?

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    Quote Originally Posted by Chuck Lee
    Pro gold evaporates and doesn't leave any goo,perhaps you are mistaking it for something else.
    I wonder more about what residue is left from the soap solution?
    Can anyone elaborate ?
    The soap solution does leave a residue. It has a very light yellow colour when liquid but no obvious colouration when dry and can be noticed under the right conditions. i.e. by looking closely to applied and non applied areas of the diaphragm.

    I would assume Pro Gold would have to leave some sort of residue for it to conduct electricity else I'm not sure how it can have conductive properties.

    My mistake for thinking it was oil because somewhere I read it lubricates connections. I've used dielectric grease in the past to coat and protect electrical contact points from oxides so my perception of what this product was somewhat skewed.

    I did however google on the product "DeoxIT GOLD" and didn't really get an answer to whether the product does conduct electricity. No doubt it does help conduct due to its protective properties but ideally we want a conductive solution on its own.

    I don't have any Pro Gold on hand else I would try it out with the Saran-wrap test.
    CLS production numbers #441 & #442 Classé CA-200 pwr-amp (SS) Audio Research SP8 pre-amp (tubes) Thorens 226 turntable

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    Andre
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    What is the main chemical in Tersaseptic? I can't find Tersaseptic brand anti-bacterial in my neighbourhood pharmacy......Very interested to give it a try....as my Aerius-i panels are muted right now...

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    Quote Originally Posted by Andre
    What is the main chemical in Tersaseptic? I can't find Tersaseptic brand anti-bacterial in my neighbourhood pharmacy......Very interested to give it a try....as my Aerius-i panels are muted right now...
    When you say they are muted, do you mean there isn't any sound or are they just very weak sounding? If there is no sound then I suspect you have other technical issues. If the bass dominates and the panels are performing poorly then this might work for you.

    0.5% Triclosan is the main ingredient besides liquid soap here. I couldn't tell you if this is what makes it conductive as there are many other ingredients that could assist in this process. Naturally there are chemicals that will evaporate after the liquid soap dries like alcohols.


    CLS production numbers #441 & #442 Classé CA-200 pwr-amp (SS) Audio Research SP8 pre-amp (tubes) Thorens 226 turntable

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    There is sound coming out, however bass dominates such that sound gets honky....
    I also have another problem, maybe you would know the answer.......the automatic turn-on switch is not working on 1 speaker. ie. it remains ON all the time, what part is likely to have failed? Checked the switching op-amp IC LM324AN, but did not solve the problem.
    N.b. thanks for the info, I think I can find Triclosan here. Worth the try as replacement of panels would cost about 50% of the speaker's new retail price!

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    Quote Originally Posted by Andre
    N.b. thanks for the info, I think I can find Triclosan here. Worth the try as replacement of panels would cost about 50% of the speaker's new retail price!
    Assuming you find another product containing Triclosan don't forget to do a quick test to validate the conductivity. Use Saran wrap (Glad wrap) stretched over a small dish and coat the surface with the conducting liquid. Let it dry and place two pennies about an inch apart. Use an Ohm-meter to measure the resistance. If there no resistance or very little, then this will not conduct the hv bias current enough to hold a charge.

    The problem with the Turn-on switch should be addressed in a separate thread as I suspect there are others who can identify this better than myself.
    CLS production numbers #441 & #442 Classé CA-200 pwr-amp (SS) Audio Research SP8 pre-amp (tubes) Thorens 226 turntable

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    Quote Originally Posted by enilsen View Post
    This might be the most significant repair that can be done to those weak sounding panels other than purchasing new elements. We can assume that the warranty has also run out by this time and you are left with no other options. There is no need to disassemble the speakers for this to work.

    I would however advise that you would at least have attempted to wash the panels once just in case there are contaminants on the surface. In any event you will have the satisfaction that they are clean and in fact weak in sound to the point that something is wrong and of course you didn’t forget to plug them in.

    Over the many years of use our panels start to loose their sparkle (weak in sound). I have been told by ML it has to do with the conductive coating failing and consequently the static charge that helps move the Mylar diaphragm doesn't retain enough charge to attract itself to the perforated stators on either side.

    After a lot of research and experimentation I have found that using a diluted solution of water and antibacterial liquid soap (brand name TERSASEPTIC) has successfully restored the weak sounding panels. You local pharmacy should have this in stock else I have also seen it on ebay (over priced).

    There are two typical areas of failure to be addressed. The primary point of failure is between the bias aluminium strip and the Mylar diaphragm. This can be found at the bottom of the speaker element hidden behind the non-perforated area. Its purpose is to conduct the static charge to the diaphragm. To restore this failing connection you will need to apply a small amount solution using a small eye dropper or a thin tube along the lower part of the perforated stator. Allow only a small amount of liquid to run down the diaphragm and meet the soft insulating rubber strip. Continue at even spaces about 1” apart until you cover the width of the speaker.

    As a precaution I recommend that you only try a small amount first to the left bottom corner and listen to the results. Needless to say if you experience the WOW factor you won't stop there.

    The second point of failure is the rest of the diaphragm. A simple hearing test will confirm if there are any weak sounding areas on the panel. This might not be obvious if the whole panel is bad so to determine if the static charge doesn't reach the rest of the panel we need to help things along.

    Take a standard RCA audio cable and insert the centre pin through one of the small holes at the base of the stator just touching the diaphragm (the centre pin should have a smooth surface). Now take the other end of the RCA cable and place the centre of that plug against any weak sounding part of the diaphragm (try to avoid resting the centre pin on the stator). Needless to say you should have music playing while doing this. The purpose of this is to transfer the static charge though the insulated cable. If the sound returns to that area of the panel then you know there is failing conductive coating. It should be noted you won’t get an electric shock from the static charge on the diaphragm (the stators on the other hand carry a punch).

    To restore sound to the rest of the panel or just sections just follow the procedure we used when using the small eye dropper or thin tube and allow the solution to run down the diaphragm to the bottom where the static bias charge originates. Take precaution not to use too much solution and do it in several stages.

    Initially the speakers will be very sensitive and require very little output from the amplifier to drive, but after 3 days the solution should have dried sufficiently to allow a more normal playing volume.

    The dilution ratio I used was about 50% as this particular liquid soap is rather thick (like syrup on pancakes). It shouldn't be too runny like water, but enough to retain its soapy consistence (like olive oil).
    Before applying any conductive liquids to the panels always do a simple test using Saran-wrap (Glad-wrap) plastic over a small dish and testing the solution after it dries. An inexpensive ohm meter will suit the purpose using 2 small coins placed at each end of the stretched plastic and measure the resistance created by the applied solution. If there is no resistance then the solution will not work.

    I can testify that this has restored my 19 year old CLS speakers for the last 30 months and would appear to be a permanent solution other than buying new elements. In fact I would claim that they have never sounded this good since the 80’s. I have waited with posting this tweak just in case it turned out to have a negative impact, but they are still going strong and can really play at volumes again.

    Hope this might be a useful fix when all else fails. There is no guaranty that this will work for all CLS speakers as through the years ML has obviously been aware of the problem and made changes to address these kinds of issues. Hence the option to purchase new panels.


    Alternative solution for weak sounding CLS panels

    How to test the quality of the conductive membrane?
    Hi,

    I know that this thread is quite old but very interesting to me. Some months ago I bought a pair of ML Aerius which are in a astonishing good shape and they do sound very good for their age of 23 years.
    One panel though is a bit weaker than the other and there is a partial difference in the sound coming from different areas of the panel. I would very much like to try this described procedure but I do have a few question.
    From what I understand the idea is to let the solution run into the bias aluminium contact strips on the bottom, right and left side of the panel edges, correct?
    Would you recommend to lay down the speaker on the side treated to make the solution soak into the bias aluminium strip?

    If you have gathered further long time experience whit this treatment I would be happy to receive an update. Off course from any one of you all that might have tried the trick.

    Thank you all.
    HiFiFuchs
    Rino Gabo
    Bavaria, Germany

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    Isn't the charge strip made of copper and running up only one side of the ESL sandwich?

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    Hi everybody,

    First of all I want to wish you all a happy and healthy new year 2017 and lots of good

    Secondly I am a bit surprised that no one has an opinion to this thread. I do know its old and "dusty" but I cannot imagine that no one has tried the tweak and either made good or bad experience with it.
    Please be so kind to let me know if it works or not.

    Thank you.
    HiFiFuchs
    Rino Gabo
    Bavaria, Germany

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