The 12AX7 high impedance amplifier triode was designed specifically for audio use and has a high amplification factor of 100. The original American 12AX7 design was copied by many companies. Here we have a Japanese version of late manufacture.
The brand name of the valve is TEN and the identification being in English and Japanese indicates the international sales.
The anode face view.
The anode space is quite deep front to back.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 48 mm tall.
References: Data-sheet, 3002 & 1040. Type 12AX7 was first introduced in 1947.