The 12AX7 high impedance amplifier triode was designed specifically for audio use and has a high amplification factor of 100. This is an American design that was copied by other companies. Mullard describe the ECC83 (=12AX7) as a high μ double triode, having separate cathodes, primarily intended for use as a resistance-coupled amplifier or phase inverter.This exhibit was made by the Marconi subsidiary in Italy and is clearly marked as such.![](../pics/aaq0434a.jpg)
The printed Marconi Italia SPA name.![](../pics/aaq0434b.jpg)
This sticker shows the Italian logo. 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. See also 1947 adverts. |