The Mullard CV4003 / M8136 / 12AU7 / ECC82 is one of the most sought-after British NOS small-signal valves for hi-fi preamps, headphone amps, DAC output stages, and some guitar amps. “CV4003,” “M8136,” “12AU7,” and “ECC82” are closely related designations for the same dual-triode family, with CV4003/M8136 being the military/spec-grade Mullard versions.

The M8136/12au7 has punchy mids and a rounded top end and is one of the best 12au7 valves around. Limited quantities available as this is an original Mullard 12AU7 and made in Great Britain.