JJ Electronic is a Slovak manufacturer based in Čadca that produces vacuum tubes, audio-grade capacitors, and handcrafted amplifiers. The company emerged in the early 1990s from the reorganized Tesla factory, which had been a major tube producer in the former Czechoslovakia, and has since built a catalog of more than thirty tube types covering preamp, power, and rectifier roles.

The brand is best known among guitarists and amp builders for its preamp and power tubes, including the ECC83/12AX7, ECC81/12AT7, EL84, EL34, 6L6GC, 6V6, and the KT66, KT77, and KT88 output tubes. JJ tubes are widely used as both original equipment and retubing options in guitar amplifiers, hi-fi gear, and studio equipment, and are stocked by major retailers and specialist tube shops worldwide.

Alongside the tube line, JJ Electronic manufactures film and electrolytic capacitors designed for audio circuits, as well as a range of guitar and high-end stereo amplifiers built in-house. The company is one of the few remaining independent European vacuum tube manufacturers, with a reputation for affordability and consistent availability rather than vintage-style boutique construction.

JJ has 11 products cataloged on Equipboard, including Guitar Amplifier Tubes and Guitar Amplifier Heads. Their gear is featured by 2 artists, with the strongest followings in Rock and Metal. Notable users include Angus Young and Peter Huss.