Sensibly equivalent¶ to:
The M8137 is a special quality version of the definitive audio double triode the ECC83. This high impedance amplifier triode was designed specifically for audio use and has a high amplification factor of 100.
This valve is still found in todays designs of hi-fi audio amplifiers. In the classic Mullard designs of the 1950s and 1960s the valve's two halves were used as second stage amplification and cathode coupled phase splitter. The phase splitter being required so that the push-pull output stage was driven correctly with the output valves driven with a phase difference of 180 degrees.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 47 mm tall.
References: Datasheet & 1040.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated March 29, 2013. shape:thin.glass.tube construction:all.glass type:double.triode age:1950.1960 base:b9a heater:6.3v pins:9 pin:1.a(2) pin:2.g1(2) pin:3.k(2) pin:4.h pin:5.h pin:6.a(1) pin:7.g1(1) pin:8.k(1) pin:9.hct