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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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    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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    Member enilsen's Avatar
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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 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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    Senior Member MPS's Avatar
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    Quote Originally Posted by Tosh View Post
    Isn't the charge strip made of copper and running up only one side of the ESL sandwich?
    I believe that is so in the current production models. Conductive coating is applied horizontally and bias supply strip must then be in the vertical edge(s). It's maybe sealed with insulation "spacer" tape in which case mentioned method might not be useful.
    CLS panels might have different construction.

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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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    I found this post very helpful for me.
    I did the shower and plant spay trick to recover my dummy aerius i and it worked!!!.

    Now I will try liquid soap trick as enlisen proposed.
    But I cannot found any the liquid soap containing triclosan because FDA announce that triclosan may causes a cancer.
    Instead, I bought two anti bacterical liquid soap - Dettol and Dial.

    if anyone knows, can you please share the result of these two types of liquid soap (Dettol and Dial)?
    I don't have ohm-meter now. I can buy the resistance meter and figure it out. But it will take some time.
    Last edited by jongtaesong; 12-25-2017 at 12:43 AM.

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