The lamp with the longest net for almost the entire 70-year history of the release 12AX7. In fact, it is a modernized version of the legendary vintage NOS Telefunken ECC83.
Lampe characteristic sound with the same depth and the density of low frequency, like a standard ECC83s, but with a more intense and more middle open upper frequencies. Nevertheless, the gain will be less lamp "evil" by about 10%. It is justified to use in the Hi-Fi audio, studio instruments, sometimes in a position V1 vintage amplifiers for use clean channel.