2x Mullard ECC81 Valves. Date Code: 1552 G3 (1953), 1552 G3 (1953). This valve has also been tested in amplifier without any noise. NOS specification: Ia = 10.5(mA), gm = 5.5(mA/V). Ia2 = 8.1(mA), gm2 = 4.2(mA/V).
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