M-300B Tube

About the M-300B Tube

The Austin Acoustic M-300B is a high-efficiency, single-ended-triode (SET) tube monoblock power amplifier built around a 300B output tube. Austin Acoustic’s product listing identifies a 436A driver tube and tube rectification, with approximately 5 watts of output and an unusually wide stated response of 20 Hz to 20 kHz. A contemporaneous listing for an M-300B version specifies Psvane WE300B and Western Electric 437A tubes, Tamura output transformers, a Tango interstage transformer and power-supply choke, silver signal wiring, selectable 4-, 8- and 16-ohm outputs, and approximately 4–8 watts. Some details therefore appear to vary by production version or source. The amplifier is intended for use with high-sensitivity loudspeakers, particularly horn systems. The manufacturer’s website still presents the model page, but the available evidence does not clearly establish whether new units are currently being manufactured or sold; confirm directly with Austin Acoustic.