The Audio-Static ES-50 electrostatic loudspeakers are a fairly thin speaker built in Holland. These speakers were manufactured in 1993, and were the smallest of the Audio-Static line. These speakers are currently not in production anymore. These speakers are 54 inches high and 14 inches wide. The active panel area is 38 inches high by 7 inches wide. These speakers are constructed of solid wood frames with the panel cutout routed out of the solid frames. The frames are constructed from four sections that are bolted together to hold the panel and input electronics. A fifth solid wood section acts as a foot to support the speaker. These speakers are surprisingly heavy and well built.
The speaker is a single panel semi-crossoverless design, where the center section of the panel runs full range, and the outer edges run from the midrange to bass. The crossover is a simple resistor in series with the outer sections of the insulated wire stators. The input section is a pair of transformers, which are driven through a series resistor and large film cap to block any DC.
The polarizing voltage is provided via a wall mount transformer (wall-wart) which produces 9 volts AC. Inside the speaker is a small 220 volt to 9 volt rectifier transformer run backwards to produce about 220 volts AC. This signal is fed into a ten stage Cockroft-Walton voltage multiplier, whose output is about 4 KV.
The original diaphragms were one half mil metalized mylar which were very conductive. This pair of speakers were purchased very cheaply because one panel was bad. Both panels were disassembled and the metalized diaphragms replaced with one half mil mylar coated with an Indium Tin Oxide coating of much higher resistivity.