DIY Electrostatic Loudspeakers / ESLs - Problem with Treble Frequency Solved

The ESLs have been performing very well up till about 3 months ago. One of the speakers developed a problem. The volume on one of the pairs was softer than the other, not by much but enough to shift the stereo image over to one side. After more listening I deternimed that it was the treble frequencies that sounded softer compared to the rest of the frequency. With advise from the designer I proceeded to trouble shoot the faulty speaker:

1. Thoroughly clean the diaphragms and stators using a vacuum cleaner.
2. Visually checked all surfaces to ensure that was no dust or insect causing a leak between the diaphrams and stators.
3. Rechecked and tightened all connections.

Still the problem persisted. I then proceeded to ensure that none of the other equipment that was connected to the speakers caused the problem. To do this I did the following:

1. Swapped the speaker cables
2. Used another amplifier
3. Used another CD player

Again, no change, the problem persisted. With all the possible culprits eliminated, the finger pointed at the electronics, and since the problem affected the treble frequencies, it must be one of the 1.2ohm resistors connected in series with the speakers. Rob had replacement resistors sent to me, free. I promptly replaced the offending resistors and the problem is gone. The ESLIII are now 100% again.

Thanks goes out to Rob of ER Audio for the great support.

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