As promised, I have the response from Dr. West of Soundlabs, as to the 'life expectancy' of Sound Labs' electrostatic panels.
I told him in an email, that the issue was posed on Audiogon, a site that I post on regularly, and asked his permission to post it, unaltered. Below is his response.
Larry,
It's nice to hear from you. I've been away from the facility and this is the first opportunity I've had to reply to your note. I'll do my best to answer your question about the life expectancy of stats. There are several things that affect the life of an electrostat, but if I were to suggest the most dominant one I would say that it is the production of internal corona discharge. Our approach has been to minimize the sharpness of anything that's within the electrostatic field. That's why we chose to have stator wires that are round in cross-section as this is the best geometry for minimizing corona. It's just about that simple.
Of course, the insulation material of the stators and the conductive coating on the membrane along with the insulation factor of the framework of the panel, all have an effect on the life of the panel. The insulation we use is a cross-linked polymer that's about the toughest one available. We started using it with our new PX panels about 5 years ago and we've not had a breakdown in the insulation since. It's been wonderful. Secondly, the conductive coating we use on the membrane tenaciously adheres to mylar, and the conductive material is smooth and doesn't invite micro-corona as sharp-edged carbon particles would. Also, the coating is covered by a micro-thin Teflon coating to make it immune to humiditiy. Lastly, the framework of the panels is very strong and stiff. Where the stators and membrane are in contact with the frame, the material is a high-resistivity plastic chosen to prevent internal leakage paths. The frame is very sturdy and uses adhesives that weld the frame members together. Steel fasteners are used also. Intersections of panel members are buttressed so that joints are very strong, which virtually eliminates panel resonances.
Our goal has been to manufacture a panel that, used in a non-hostile environment and is not pushed beyond specs, is a forever panel. We have been very pleased with the reliability of our PX panels. I feel under the circumstances that I can say that I don't know of any limitations to their longevity. This is supported by the exceptional reliability that our PX panels have exhibited over the years. However, even our previous technology was good. We still have some customers that contact us who have speakers that are over 30 years old and they are still functioning well.
If any parts within the panels have sharp edges or small radii, it invites corona discharge. Corona is extremely oxidative and can destroy almost any material, including metal. The battle is to avoid this circumstance, which has been a major part of our technology. I hope that this adequately answers your question. If not, please let me know.
Sincerely,
Roger West
For further information regarding corona in this context, simply use Google to search, 'electrical corona discharge/damage, and so on.
It seems fairly obvious that Sound Labs is doing all that is currently technically possible, to minimize foreshortened panel life...and further, based on this answer, that we may be at the point at which this is not an issue...as he states, "I feel under the circumstances that I can say that I don't know of any limitations to their longevity."
I thank Dr. West for his forthright and timely response to a sincere question.
Larry
