A New Low-Noise Circuit Approach for Pentodes
In the tube world, it is taken for granted that if you want a low noise amplifier you don't use a penthode; penthodes have higher noise and more 3rd harmonic distortions than a triode. But Frank Blöhbaum doesn't take things for granted. He researched this common wisdom and found out that penthodes can be used in low-noise applications with advantage, and shows some innovative circuitry to do just that. The article also contains an extensive comparision between different tubes for noise and distortion performance.