The Plasma Tweeter

1
The Plasma Tweeter

• Colin Joye
• Massachusetts Institute of Technology

2
What is a Plasma Tweeter?

• Sound is generated by the motion of a high
  voltage corona discharge flame.
• An audio signal changes the flame size rapidly,
  creating sound waves!

3
Advantages

• The Electric flame has no mass and hence perfect
  transient response!
• It also has no directional preference and acts
  like an omnidirectional acoustic point source!

4
Circuit Operation

• A feedback-driven oscillator generates high
  voltage for the corona discharge.
• The audio signal modulates this voltage.

5
Physics

• Oscillation frequency must be higher than 3-4 MHz
  to avoid audible hiss.
• At high frequencies, the ions form a region of
  space charge, perpetuating the corona.

6
Future Plans

• How low can the frequency response go? Lower
  midrange?
• Increase power efficiency.
• Linearize the whole system.

7
References

• Siegfried Kleins patents 2,768,246
• AudioXpress magazine, April 2003, Vol. 34, Issue
  4, Build a Plasma Tweeter
• F. W. Peek, Dielectric Phenomena in High Voltage
  Engineering, 3rd Ed., McGraw-Hill Book Company,
  1929.
• A. Von Engle, Ionized Gases, Clarendon Press,
  1965
• http//www.plasmatweeter.de (U. Haumann)
• http//www.ionAudio.net (Colin Joye)