Partition Noise and the ‘BestPentode’ Revisited

Author(s): Blencowe Merlin

In Linear Audio Volume 0, Frank Blöhbaum proposed an interesting circuit for use with pentodes, which he called ‘BestPentode’. Blöhbaum claimed that this retains the basic properties of the pentode but eliminates its partition; his article also implies that the ‘BestPentode’ has lower EIN even than the simple, triode-connected pentode, and Merlin Blencowe does not agree with that.

In his article he demonstrates, by straightforward theory and experiment, that ordinary triode connection always results in the lowest-possible EIN from a given pentode, and that the ‘BestPentode’ when operating into the same load and with the same Ik and bias voltage, must always be noisier (though usually negligibly so).