300B Triode Vacuum Tube

The 300B is Western Electric's legendary directly-heated power triode, originally designed in 1938 for telephone repeater amplifiers and theater sound systems. It produces 8-10W in single-ended Class A with a linear, low-distortion transfer characteristic that has made it the reference standard for SET amplifiers. The tube's mu of 3.85 and plate resistance around 700 ohms yield a combination of authority and finesse that few power tubes match. Original WE 300Bs command collector prices, but current production from WE (reissue), Takatsuki, Elrog, and EML offer legitimate alternatives with varying sonic signatures.