A low power amplifier architecture that employs a single-ended (single triode) push-pull (SEPP) vacuum tube and output transformer arrangement, and that cancels unwanted amplifier signal components such as hum and noise. The SEPP amplifier operates to cancel power supply ripple and local EMI induced noise in the output transformer by providing reverse polarity of the primary coils of the output transformer.

A low power amplifier architecture that employs a single-ended (single triode) push-pull (SEPP) vacuum tube and output transformer arrangement, and that cancels unwanted amplifier signal components such as hum and noise. The SEPP amplifier operates to cancel power supply ripple and local EMI induced noise in the output transformer by providing reverse polarity of the primary coils of the output transformer.

A casing unit is provided that includes a cylindrical peripheral wall portion of quartz or glass, a cover of metal, and a fixing unit configured to fix the casing unit in or to a housing of a hi-fi tube amplifier. Also provided is a hi-fi audio tube amplifier that includes a plurality of tubes configured to amplify audio signals, and a plurality of the afore-mentioned casing units. Each casing unit encloses one tube of the plurality tubes at three sides, and the fixing unit of each casing unit is configured to fix the respective casing unit in or to a housing of the hi-fi audio tube amplifier.