Hola. I am going to chime here... here is your explanation... from ML Univerity: The MartinLogan electrostatic diaphragm uses three key parts; the MicroPerf stator, the ClearSpar and the diaphragm. See below.
Stator
The first key piece to the operation of a MartinLogan electrostatic speaker is the MicroPerf stator. Each ESL assembly has two; one on the front and one on the back. These steel stators are each insulated via a proprietary method in our facilities in Lawrence, Kansas. This allows the stators to conduct up to 12,000 volts and yet be completely safe to the touch. The term MicroPerf refers to a MartinLogan patented technology of using a surface that utilizes a larger quantity of smaller holes over its surface. This allows more air to flow and thus more sound output created from a smaller panel.
ClearSpar
Our ClearSpar technology utilizes technology derived straight from the cost no object Statement e2 loudspeakers. This technology enhances the transparent look of the speaker, increases efficiency and dynamics and acts as an excursion limiting device. Many folks confuse that these provide the electrical energy directly to the diaphragm. This is absolutely NOT the case. The ClearSpars serve several purposes one of the main ones is related to excursion.
In a conventional, or “cone”, loudspeaker there are several parts that act as the suspension; the most important of which are the spider and the surround. These two structures prevent the cone from traveling too far and allowing the voice coil to travel outside of the gap. If it did, it would damage the speaker.
The MartinLogan patented ClearSpar acts much like the suspension in a conventional driver. Its design prevents the diaphragm from traveling to far and touching the surface of the MicroPerf stator. Remember, both the diaphragm and the stators receive an electrical charge. If they were to touch, it will likely arc and damage the loudspeaker. This design is a MartinLogan exclusive and is one of the reasons our panels set new standards for reliability in the ESL world. The technology truly makes it next to impossible to damage the panel from being over driven and makes it one of the most reliable parts of our loudspeaker systems.
Diaphragm
The diaphragm is made from a .0005-inch thick polyethylene terathylate… a material whose consistency reminds most people of window tinting film. We lovingly refer to it as "PET" film. This PET material is treated to a plasma deposition process that took over three years to perfect. This process applies a uniform, durable, conductive coating to the film that enables a high-voltage charge to flow over its entire surface. Mass-less for all practical purposes, this diaphragm can reproduce clarity through the entire range of human hearing.
The electrical information from your amplifier passes through an audio transformer which is responsible for taking the incoming signal and increasing it to a higher voltage. This signal passes into each of the stators with opposing polarity. In other words the front and rear stators are always opposite charges. If the front is positive, the back is negative or vice versa.
The sandwiched diaphragm receives a consistent positive charge. This charge comes from a power supply that receives its energy from your electrical outlet. This is the reason you must plug an electrostatic speaker into the wall...
As the signal passes through the stators, the positively (+) charged diaphragm is attracted to the stator surface with the opposite or negative (-) charge. During this process it is also being pushed, or shoved away by the stator with the positive (+) charge. This causes the diaphragm to physically move forward and back at an extremely rapid pace, which in turn moves air. When we move air we create? Sound! See below.
Every MartinLogan electrostatic loudspeaker is hand built. From applying the proprietary insulation surface to the stator, to stretching the diaphragm and sandwiching it between the stators… old world craftsmanship meets new technology. It’s no wonder the “Stat Panel Room”, as it is affectionately called, is the most memorable experience folks have on their trip to our facilities...
So the electrostatic speaker behavior is like a big capacitor. It is not resistive as the ribbon made or flat panels like Maggies, and are not as dynamic speakers that are coils (inductive). The capacitors have a property to have charge and save it. The capacitor charges itself. This is why even being uplug from the mains AC, their charge starts to produce that sound, until there is no charge at all. If you can listen something, it is due to the voltage applied by the amp (very little voltage). Happy listening,
Roberto.