2A3

The 2A3 is a directly-heated power triode introduced by RCA in 1930, delivering about 3.5W in single-ended Class A. It has a remarkably low plate resistance (~800 ohms) for a DHT, giving it excellent damping factor and tight bass response without feedback. The 2A3 occupies a sweet spot between the delicacy of the 45 and the authority of the 300B, with a midrange that many consider the most natural of any power tube. Single-plate versions (such as the RCA mono-plate and Sovtek 2A3) are generally preferred over the original dual-plate construction for lower distortion and better linearity.