enilsen
Well-known member
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?
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?
