BUGERA Amplifier Tube (12AU7) The 12AU7 is a classic preamp tube found in many vintage and current amps, specifically in phase-splitter or driver stages The BUGERA 12AU7 is a premium grade version to substitute standard 12AU7s in any amp and position It provides high levels of gain and low output impedance, with superior reliability and consistency and also features an extremely open and expressive tonal spectrum, with a balanced and smooth frequency response