A Stiff Breeze

Massless Speakers Part 3


Dr. D.M. Tombs and the Corona Wind Loudspeaker, 1955
Could be corona

Dr. David M. Tombs is in the theory section as the designer of a corona wind loudspeaker in the UK in 1955. This design was never patented or commercialised but was demonstrated at the Imperial College, London, and at the AES in New York.  A small article by Tombs appeared in Nature in 1955 and Electronics in 1957.

Early in its development the American Gerald Shirley from Televex was involved in the project, focusing on trying to commercialise the design.  He authoured a few more larger articles in Radio and Television News (1956), the JAES (1957) and Radio-Electronics (1957).  However it does seem that it never came to pass as a product for sale.

Gerald Shirley did get exclusive rights to the speaker for manufacture by Televex Co. in the US as well as applying for a patent on it. No patent exists though, so it looks like it wasn't pursued to being granted. Tombs had been involved in a wide variety of other technology developments before this and went on to pursue his career in a different direction (at Hoover) afterwards. The book Acoustics and Vibrational Physics (1966) did feature a section on it as did Electroacoustics (1970).  For further technical research on it the paper by Matsuzawa 1973 is detailed about a speaker based on Tombs' design.

A corona wind loudspeaker
Tombs' Corona Wind Loudspeaker Prototype
The physical basis for this loudspeaker is the ion or corona wind effect.  It could be considered a true ionic or ion loudspeaker as there is no plasma produced and the main effect is that of ions being driven through the air from a high voltage potential and colliding with air molecules.  A more recent study also suggests that electrons may have a direct effect (Nature 2018).  One of the primary promises of this technology over plasma is that it can be made to produce frequencies over the full audio spectrum.  It lends itself to using multiple points (or wires) to create more surface area and therefore can move more air allowing lower frequencies to be produced than plasma tweeters.  The major disadvantage would be ozone gas creation for which it is very efficient.

Although not cited by Thomas Townsend-Brown, his patent from 1960 is an identical description of Tombs' corona wind loudspeaker, including both the single ended and push-pull versions. Nothing beyond this and his 1967 patent was produced by Townsend-Brown.

Around 1973 the audio designer John Gordon Iverson designed a prototype corona wind loudspeaker and he is quoted as referring to work from the 1950's on which it is based.  This "force field" loudspeaker didn't get beyond prototype and descriptions of it do describe a large panel version of a full range corona wind speaker.  Beyond Klein's plasma tweeter which bears no similarities, there was little else developed around the 1950's so it would seem that it was Tombs' work he found. 

Part 4 - Popular Plasma
How Old?
Actual Plasma
A Stiff Breeze
Popular Plasma
Don't Breathe
Future Thinking
 
 
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Info about plasma speaker and plasma speakers

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