Description of the ESL 175

Type: Full range Wire Stator ESL
Initial designer: E. Fikier
Dimensions:
ESL size: 1600 x 260 x 80 mm
HV Power supply: 7500 V
Audio transformer: 1:50
Amplifier power: min. 40 W
Sensitivity: 82 (88) dB (1/W/1 m) with an audio transformer 1:50 (1:150)
Freq. response: 60 Hz...20 kHz (audio transformer 1:50); 40 Hz...20 kHz (audio transformer 1:150)

For an exact description of the ESL 175 I have to refer to the book of E. Fikier.

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Experiences

My experiences with this design are not very positive. The diaphragm that I used at first (metalized Mylar) burned away completely and as a result the sensitivity reduced dramatically. A second attempt with foil also used in the Finals got much better results but frequencies below 120 hertz are barely noticeable. Over the period of a year sensitivity reduced and the deformation at normal levels is enormous. According to E. Fikier this type of electrostat -with the used audio transformer and high power supply- should work well down to 60 hertz. There are also some mistakes in E. Fikiers book.

I am planning to build a smaller ESL with a crossover point at about 300 hertz with a active woofer with power amplifier.

John Musterd