OVERVIEW

PX-25 has a very similar midrange sound to the 2A3 but much more extended frequency extremes and more power. It also employs a high Mu tube, which allows the design of an amplifier to achieve a greater damping factor (better control over speaker drivers). Compared to a 300B, it possesses a lower grid-to-anode capacitance (around 8pf rather than 13pf) and a higher anode impedance (1.2k versus 800 ohms).

This allowed us to design an output transformer with extended bandwidth that transcends the capabilities of a 300B or 2A3. The result is a micro-watt amplifier capable of much more impressive performance.

The total project and combined development of this design took about 17 months, including time spent with the research of the actual tubes from Riccardo Kron.