Sensibly equivalent¶ to:
The 12AU7 is a double triode with separate cathodes. An amplification factor of 17 is quoted. The 6C4 is half of the 12AU7.
The side view of the anode shows the ridges pressed into the sheet to aid rigidity. The coating helps improve radiation efficiency for better cooling.
See also ECC82 from Mullard that designates the valve with both the Mullard ECC82 and the American 12AU7 designations.
The thin glass tube envelope is 19 mm in diameter and the length excluding the B9A base pins, is 48 mm.
References: Datasheet & 1040. Type 12AU7 was first introduced in 1951.
Absolute Maximum Operating Conditions¶
Updated January 31, 2013.