Stromberg Carlson Console Radio

[Jeffhs]

Originally posted by Rob
Jeffhs, All,

Just a technical point of correction. The field coil speakers are often correctly called just that. They are also known as "electrodynamic' speakers as opposed to permanent magnet 'dynamic' speakers. Jeffhs used the term electrostatic loudspeaker. That is an entirely different animal which resembles an air dielectric high voltage capacitor. The diaphragm that produces the sound is conductive and is pushed and pulled between two outer perforated conductive panels by electrostatic forces created by a high voltage power supply and modulated by the audio signal which is increased in voltage with a special step-up transformer.

I stand corrected, Rob--thanks. Your description of these units rings a bell, as there is an electrostatic tweeter in my Zenith K-731 AM-FM radio (no wonder the set sounds so good). I posted a question about that unit last year in this forum; the reply stated pretty much the same thing as you said here, namely, that the electrostatic tweeters operated directly from B+. In 30+ years of working with electronics, I had never seen an electrostatic tweeter in any kind of audio or radio equipment until I saw the one in my Zenith. Had me scratching my head for awhile--this blue box with a cable hanging from it, connected to a terminal strip on the chassis. Oh well, at least now I'll know what I'm looking at next time I see one of these things!