Our old site had an article on random noises in electrostatic panels. As we are having some difficulty reproducing some of the features on the old site, I am repeating what I can remember of it here.
A lot is going on in an electrostatic panel – footballs are being kicked around in highly charged air. The panel can, of course, be plain faulty, as with any component – but what we are addressing here are low-level random noises that can, from time to time, appear in brand new panels. Apart from the annoyance factor, there is no need to worry – it’s usually a bit of trapped static and most noises disappear in time. Unplugging the speaker overnight can sometimes cure the problem. Older panels rarely suffer from this, but that is because they have lost sensitivity (output) over the years. The noises that sometimes appear in new panels are largely to do with the fact that they are new and are performing with maximum output and efficiency. Electrostatic panels are affected by two factors: temperature and humidity. Truth to tell, there is no “correct” HT voltage for a panel to work at. Just the ideal voltage for the panel to work at given the conditions in which it is operating. A good many manufacturers of electrostatic speakers set the “ideal” HT voltage by gradually increasing it until the panels becomes noisy (usually fizzles) – then the HT voltage is backed off around 15-20%, and that should be the ideal voltage for the panel under its present working conditions. After a few years, a drop in the panel’s sensitivity means that the HT can be increased without inducing any noise – but little is to be gained, so best to leave alone. Dust covers do, of course, lessen the panel’s tendency to develop noises, so these should be checked every few years to ensure no small tears have appeared in the polymer. Most of our panels are “oven-treated” to equalize tension and dry out any part of the glue, the slow evaporation of which that might cause noises, but still this can’t assimilate the exact conditions in which the panels might be operating. Most low-level random noises (ticks, fizzles etc) will disappear in time as the panel settles in. If this is not the case, we may, of course, be addressing a genuine fault, and we shall be happy to re-test the panel and correct the fault. In short, DO NOT panic if a random noise is heard in a particular panel: panels are tested for an average of fifty hours before dispatch, so the problem might never occur, but if it does please give the panel time to settle before reporting your findings. It is more often a “quirk” of electrostatic panels rather than a genuine fault condition.

Ron Best,
February 2019.