End of an Era for TO3 Lateral MOSFETs

Profusion has issued an End-of-Life (EOL) notice for the longstanding metal can versions of its Exicon line of lateral MOSFETs.

Lateral MOSFETs shot to fame in the 70s and 80s when Hitachi first released the 2SJ50/2SK135 and 2SK176/2SJ56. Developed specifically for linear audio amplification,they earned a legendary status in the audio industry and became much coveted components when Hitachi ended their production. In 1993, Profusion introduced the Exicon brand; specialist lateral MOSFETs that were comparable in design but suffered less thermally related distortion.


For the last 10 years, Exicon has been the only manufacturer of TO3 Lateral MOSFETS, which continued to be a staple for designers of high-power analogue amplifiers. However, due to a significant increase in manufacturing costs and a gradual decline in demand, Profusion has deemed it time to cease production of the venerable audio component this year.

The list of amp manufacturers that used lateral MOSFETs is vast: Aguilar, Ashly, Audio by Van Alstine, Chevin Research, Classé Audio, Goldmund, Hafler, HH, Hughes and Kettner, Laney, Mesa Boogie, MTX SCS, Nagra, Soundcraftsmen, Trace Elliot, Vestax… and many, many more.

Exicon MOSFETs would become the first choice for John Linsley-Hood, revered developer of the ‘Simple Class A Amplifier,’ and have since been proposed for numerous revisions and amp designs in the pages of Electronics World. Inspired by their use in high quality amps by Swiss manufacturers such as Nagra and Goldmund, contemporary audio designers including Soo In Chae of Korean manufacturer Bakoon praise the lateral MOSFETs’ “outstanding properties … the quality of sound is indeed exceptional.”[1] HiFi.nl recently asserted that Exicon “belong to the cream of the crop in the field of FET audio components.”[2]

Exicon MOSFETs have also long been a foundation of the DIY amplifier community, where their high speed and exceptional sonic characteristics have made them the first choice for even the most scrupulous of audio enthusiasts.

Exicon’s two plastic lateral MOSFET versions, the TO247 and TO264, remain active and recommended for new designs, and are available at profusionplc.com and via exicon.info.

LINK: Official Notification of EOL