Today, there are many manufacturers offering commercial versions of electrostatic loudspeaker systems. These range from very small units intended for portable or tabletop applications to large floor standing models designed for public address needs. Some designs offer both high efficiency and wide frequency response while others focus mainly on either performance or size. One common feature shared among all types is the requirement for a source of voltage capable of driving several kilovolts into the plates. While some modern designs utilize specialized transformers to produce voltages up to tens of thousands of volts, most still require separate supplies to generate the required potential difference across each pair of screen electrodes. Proceed to read this article if you are trying to find an answer to “how do electrostatic speakers work?”.
What are electrostatic speakers?
An electrostatic speaker uses two large conductive plates. One plate has a positive charge while the other has a negative charge. When air molecules pass between the plates, they pick up electrons from one plate and then deposit them onto another plate. Because each molecule carries a certain amount of electric charge, it becomes polarized by the surrounding charges. As the molecules move away from the positively charged plate toward the negatively charged plate, their movement is influenced by the polarity of those nearby. By varying the strength of the electrical field around the plates, we can control where exactly the particles go. These changes cause the molecules to vibrate inside the chamber and produce sound waves.
An electrostatic speaker uses a “positive” charge to create a static field around its cone. As the positive charges move toward the ground, it creates a negative potential between itself and the earth. Then, when a conductor such as air comes near the charged area, it completes the circuit and can induce current flow within the air molecules, causing them to vibrate. In this way, the entire volume of space surrounding the cone becomes part of the driver mechanism. Modern electrostatic speakers operate on the principle of static electricity.
What’s their history?
The first attempts at creating an electrostatic speaker are attributed to Dr. Rene Toupin who used his own homemade device in 1884. In 1888, E.G. Plummer patented a similar design, which he called “the voice transmitter.” The original French name for these devices was ‘électrostats’.
In 1929, Lee de Forest invented the triode amplifier by combining elements from telephone repeaters with early radio technology. This invention made possible amplification of low power signals such that they could be heard over long distances. However, it took until 1962 before electronics companies began mass production of transducers based on this principle. At least one company, Audio Engineering Society Inc., continued to sell their version of the Electrostat through the 1970s.
How does an electrostatic speaker work?
The principle behind how it works isn’t that complicated – but we’ll try to explain: The first thing you need to know is what’s called “electrical polarity”. A positive charge is like having a piece of paper with a negative image on one side; there are electrons moving around this positive “charge”, which causes the area where they move outwards to be more negatively charged than other parts of the screen. This means that if the electric field at some point is greater in magnitude than all the forces acting upon it, then the net effect will result in the movement away from this position towards another location where the field strength is less. In other words, any object placed into such a situation would accelerate until its acceleration vector was equal to the direction of the electric field. Now imagine that instead of just placing something into a region of high-magnitude fields, we can place a wire or rod into that same region! We’ve created a conductor whose ends are connected to electrodes, so the potential difference across these leads can vary as desired. As long as the voltage source has enough power to overcome whatever resistance exists within the circuit, charges will flow down through the conductor, creating a path for those positive ions flowing outward.