Plasmatronics is a company, founded by former Air Force Weapons Laboratory (now Phillips Laboratory) scientist Dr. Alan E. Hill, which produced a

plasma speaker Plasma speakers or ionophones are a form of loudspeaker which varies air pressure via an electrical plasma instead of a solid diaphragm. The plasma arc heats the surrounding air causing it to expand. Varying the electrical signal that drives t ...

design. This was first demonstrated at the 1978 Winter Consumer Electronics Show. The product used a conventional dynamic

loudspeaker A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or ...

with an integrated

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost t ...

for low frequencies. For a tweeter it used a

as a near-massless driver. Uniquely, to prevent ozone and NOx emmisions it sourced helium from a tank in the back of the unit. While praised for accurate sound reproduction at demonstrations, the system had a number of disadvantages, including high cost and periodic handling of heavy compressed

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

cylinders.

External links

website dedicated to the plasmatronics loudspeaker
Loudspeaker manufacturers Audio equipment manufacturers of the United States