I have been a fan and builder of Electrostatic Loudspeakers (ESL) for many years and have built at least a dozen different designs before settling on the Full Range set. One thing that always bothered me about ESLs was the need for a wall outlet to power the high voltage supply. It meant one more cord across the floor, which did not help in the WAF department.

I regularly turned off the HV supply when the speakers were not being used as a safety practice and to keep the stators from attracting dust. It required either some sensing electronics to power down the HV supply when the units were not in use, or manually unplugging the cord or turning off the AC source. If only I could do away with the AC supply all together...

The design goal was a self-bias supply. In essence, have the ESL operate like a normal speaker, with only a speaker jack on the back. We do that by utilizing the voltage already available, that of the audio signal.

As always, bare boards or a completed units are available for sale, send me an email. The bare boards are $10 each with completed and tested boards at $45 each.

Ken Seibert
ken@kenseibert.com
Redondo Beach, CA