6F4P (6Ф4П) Triode Part

All tube operating points below are by no means definitive good sound recipe for your particulate tube project. Lowest THD point is not necessary best sounding one and there is always some variance even in a NOS tube batch from the same manufacturer!  Below information is only useful as a general starting point and is ment to get you in a ballpark when no measurement equipment is available.

Lowest THD operating point spectrum

4.5mA, -0V BIAS, 244Va

Other operating points

4mA, -0V BIAS, 232Va
1.5mA, -0.96V BIAS, 157Va

Traced plate curves


Interesting triode that can operate with positive grid voltage! Curves looks very linear too, although there is some wrinkles. But that’s because of a very small currents involved – measurement errors are magnified too.

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