Current (new) production 300B tubes like the
Electro-Harmonix 300B and the JJ 300B sound wonderful at a fraction of
the Western Electric 300B price. A direct coupled driver stage and a low
mu triode array are the specific reasons why this design works so well.
Good output transformers are the key to good performance. Magnequest
FS-030 or XE-60S are good choices.
The schematic for the 300B Single-Ended Vacuum Tube Amplifier is shown below. Using audio output transformers with a primary impedance of about 3000 to 3500 ohms you can expect about 8W of output with at about 2.5% THD.
The schematic for the 300B Single-Ended Vacuum Tube Amplifier is shown below. Using audio output transformers with a primary impedance of about 3000 to 3500 ohms you can expect about 8W of output with at about 2.5% THD.
