One audiophile area that many would not consider territory for the plasma loudspeaker is the headphone. With dangerous high voltages and toxic gases it would not be seen as an alternative by most designers. But considered they have been and have even become products.
The earliest documented example is from the creatively diverse mind of Gregor Antes in 1964. With a photo and short article it appears he developed a demonstration pair of glow discharge plasma headphones. Based on the frame of a stethoscope and using quartz tubes with platinum electrodes the report indicates they were at least successful in reproducing music. There were no regards to any safety measures made but it looked like a remarkably compact unit.
Starting development around 1982 and released as a product in 1984, the Plasmasonic 1 from Audio Reference was the first commercial pair of plasma headphones. Designed by Henri Bondar, patented in 1986 by Jean-Claude Fourrierer, they used a push-pull corona discharge arrangement with amplifiers in the headphone. This design would be closer to a single set of corona electrodes from Dr. David Tombs' push pull corona wind loudspeaker 1955, but using the grids as modulated anodes to point cathodes. Apart from basic grounding and shielding there were few safety measures, it produced ozone and the electrodes degraded over time.
The preamplifier/power supply had a manual bias adjustment control - as with any corona discharge design the humidity, temperature and altitude would affect the maximum bias voltage usable before excessive noise was made. The bias would need to be reduced to reduce noise and this would also reduce the maximum volume, already quite low at 103dB. Measurements from the one review of the time showed a fairly flat midrange and an extended treble frequency response. Bass started to roll off from 200Hz which was confirmed by those who heard them saying they were very bass light.
Nevertheless, creating these as a commercial product was a huge achievement especially with 1980s technology. A few thousand sold as a very niche product, with conventional headphone designs being a more convenient proposition to most listeners. Jean-Claude Fourriere later went on to attempt the build of a full size loudspeaker based on the technology, but the production version of the AHL Tolteque was released as an electrostatic.
The thought of applying the technology to headphones did not die out completely after the Plasmasonic 1. In 2008 Audio Technica obtained a Japanese patent for a horn loaded, valve amplifier driven, glow discharge plasma headphone. This would have been closer to using a Klein Ionophone as a headphone. A later Chinese patent by Shi Peng in 2016 outlined a very basic design of the same idea. Otherwise most conversation about using such devices is treated as either a joke or as impossible by the hifi community.
In 2025 a new design for a glow discharge plasma headphone was commercially released. Called massless and designed by Adam Chambers for Audio Chambers. It is unlike the Plasmasonic, using glow discharge plasma and a replaceable in-ear capsule to allow electrode replacement. The glow discharge plasma is unaffected by its environment and the in-ear design allows a full frequency range more closely following a Harman curve. Safety concerns are addressed with all high voltage components including the power supply and amplifier being sealed in the headphone itself. Toxic gases are extracted and filtered and safety cutouts are employed in several areas. This design shows that with enough effort the limitations of plasma audio technology can be overcome and allow the audible benefits of it to be heard.
