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Alternative solution for weak sounding CLS panels

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enilsen

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I own a pair of CLS's that were weak in sound on the one panel and mine are from the mid 80's production numbers #441/442. This might or might not apply to other owners, but after doing the vacuum and shower procedure my speakers did return to normal operation again. At least for a couple of days.

My assumption at first was years of grime that had built up on the membrane was draining the static charge from it and the thorough cleaning with warm water might removed this kind of obstacle restoring them to near factory condition. No one has stated yet that the static charge is the culprit in question so maybe there was a physical failure here instead.

I then e-mailed ML to see if they had any other solutions to my problem and was told that the panels needed replacing due to the fact that the conductive coating was failing. Other posts report the same answer as I got from ML.

I was however not quite satisfied with this response as there was a significant replacement cost involved and my personal attempt that almost worked in restoring the sound to my vintage CLS's. I figure that I had nothing to loose by experimenting with the cleaning process in question and trying to understand why showering the panels temporary restored the sound.

After several showers later with the same positive results I got tired of doing this extreme man handling of my speakers and resorted to using a small plant sprayer filled with water. I soon discovered that doing a very small squirt to the lower left side and lower center portion of the panel yielded the same positive results. This spraying process is done while the speakers are “ON” and music playing at low volume. Needless to say that this does appear to be a dangerous task at hand and the threat of electrocution a very real possibility, but I am writing this as a testimony to surviving the ordeal and can sincerely conclude that ML have done a brilliant job with insulating those high voltage stators.

Unfortunately using the plant sprayer filled with water is only a temporary solution to this problem and I can only speculate that it is restoring the electrical connection between the bias aluminum strip at the base of the conductive membrane. Eventually the water evaporates and the restored connection is lost to resume where we started from when the sound was weak (This is only my theory and others please comment if you have any other ideas).

I have since improved on this process and after a lot of research and experimentation found that using a diluted solution of water and “ANTIBACTERIAL LIQUID SOAP” instead of regular tap water has resulted in a more permanent connection between the bias aluminum strip and the conductive membrane. It has worked for over 15 months now after a single application and I can not hear any deterioration of the sound yet. The sound is evenly projected from the whole panel and efficiency has improved dramatically. I welcome any comments on this if anyone has a better solution to the problem other than replacing the panels or using just the shower and hair drier to re-establish near factory sound.

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.
The product I used is called “TERSASEPTIC” purchased in a Canadian pharmacy, but I’m sure other liquid soaps with similar conductive properties would also work.

The idea of attempting to repair the panels using liquid soap comes from other sites where owners have restored the conductive coating on Quad electrostatic speakers by applying either graphite powder or liquid soap. For some odd reason conductive coatings are well kept secrets so no one has pointed me in the direction of what brand names would be suitable.

Note. Applying this solution would be best achieved by 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 membrane (not the stator!) and meet the soft insulating rubber strip. Continue at even spaces about 1" apart until you cover the width of the speaker.
 
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goudey

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This approach may restore my 80's vintage CLSs

My CLSs have been in storage for a while now, and I have been lurking in this forum waiting for a post just like this. I have known of the shower trick for quite some time, and have been intending to try it this summer, but have doubts that it will be adequate. Your thinking-through the cause-effect of the shower treatment fix being temporary and the subsequent experiments with liquid soap is brilliant in my opinion (wish I'd thought of it). Basically applying a new connection between the polarizing voltage terminal and the diaphragm coating, without disassembly.

I do, of course, want details. I am searching for a source of the soap, looks like I can purchase on-line. What dilution ratio? Using a dropper at one foot spacing? (thats only 2-3 points along the bottom of the diaphragm). So we want to keep clear of the spacers I presume.
 

enilsen

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You shouldn't have problems acquiring this liquid soap that I suggest to use. I don't think you even have to go to such lengths as to purchase on-line as most drug stores should carry this in stock.

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).

The spacing at the bottom was my mistake, but that probably would work using 1 foot intervals. It should read 1" (1 inch intervals) to cover the whole strip. The static charge will rejuvenate even when only a small portion of the strip is in contact, but you will notice less sound from the membrane which is farther away to the left or right of that contact point.

My suggestion to anyone unsure of this fix is to try a single drop at one end of the membrane (bottom left) and see if you can hear a noticeable improvement.

Needless to say that this process has to be applied to both left and right panels in a similar fashion else one speaker will be a lot louder than the other. Also keep in mind that when this is first applied the efficiency of the speakers will be quite significant, but after about 3 days they should calm down when the solution has dried up and normal operation is restored. The dried liquid residue has an oily stickiness to it and doesn't flake off so it continues to act as a conductor long after it is applied.
 
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