The 12AX7 (ECC83) vacuum tube was invented almost 70 years ago and is still an absolute necessity for every electric guitar tube amp and a wide range of hifi audio tube amplifiers. Another common name for the 12AX7 tube is ECC83 and for premium versions the 7025 and ECC803 audio tubes. Originally, the 12AX7 / ECC83 vacuum tube was introduced to be a superior option for lower noise and microphonics over the 6SL7 tube that was commonly used in the 1940s. As well it offered more gain. Today, a look at almost any guitar tube amp, be it Fender, Marshall, Vox, or any other, will prove the 12AX7 / ECC83 / 7025 tubes are here to stay.
Be sure to click the “Additional Info” tab when viewing a specific 12AX7 / ECC83 / 7025 tube. There you will find related articles and downloads such as datasheets, pinouts, ratings, and matching information when available. Other excellent links for technical information can be found at 12AX7 in Wikipedia, 12AX7 in Duncan Amps, and 12AX7 in The Tube Directory.