MULLARD M8136 / CV4003 / 12AU7 – MATCHED PAIR (2 PCS)
Top Ring Getter
Black Plates
Made in Great Britain
Military M8136 / CV4003 / 12AU7
New in White Box
Amplitrex AT1000 Tested
Up for sale is a matched pair (2 pcs) of premier vintage NOS Mullard M8136 / CV4003 dual triode vacuum tubes, manufactured in Great Britain and supplied in individual white boxes. Built with heavy-duty black plate structures and top ring getters, the M8136 is the ultimate military-spec, ruggedized, long-life industrial equivalent to the standard 12AU7 / ECC82 family. Celebrated worldwide for exceptional soundstage depth, rich midrange harmonic texture, and ultra-low microphonics, these tubes make an elite upgrade for high-end audio preamplifiers, line stages, and studio equipment taking 12AU7 series valves.
Both tubes have been fully tested on a precision Amplitrex AT1000 tube tester. Measured Plate Current (Ip in mA) and Mutual Conductance (uMhos) alongside percentage performance ratings relative to nominal factory reference specs (Reference: 10.5 mA / 2,200 uMhos) are detailed in the table below.
| Serial No. | Triode Section | Plate Current (Ip) | Mutual Conductance (uMhos) | ||||
|---|---|---|---|---|---|---|---|
| Ref Spec | Result | % Ip | Ref Spec | Result | % uMhos | ||
| SR.NO.3439005 | Triode 1 (T1) | 10.5 mA | 10.2 mA | 97% | 2200 | 2400 | 109% |
| Triode 2 (T2) | 10.5 mA | 8.8 mA | 84% | 2200 | 2300 | 105% | |
| SR.NO.4599004 | Triode 1 (T1) | 10.5 mA | 9.3 mA | 89% | 2200 | 2400 | 109% |
| Triode 2 (T2) | 10.5 mA | 9.2 mA | 88% | 2200 | 2300 | 105% | |
Technical Note: Custom duties and taxes are the responsibility of the buyer in their country.
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