MULLARD ECC82/12AU7 – MATCHED PAIR
GRADE: GOLD SERIES | VINTAGE BRITISH MEDIUM-MU DUAL TRIODE
ECC82 / 12AU7 Dual Triode
Blackburn Factory (Date Codes: B7A / B7L)
Long Plates
Top Square Getter
New in White Box
Amplitrex AT1000 Tested
Up for sale is a matched pair (2 pieces) of highly coveted vintage Mullard ECC82 (12AU7) dual triode vacuum tubes, packed in white boxes. Made in Great Britain at the famous Blackburn plant (featuring etched date codes B7A and B7L), these early-production tubes feature classic Long plates, a distinctive top square getter, and crisp white BVA printing. Highly praised in audiophile circles for their warm midrange, lush tonality, and exceptional spatial imaging in preamplifiers and Hi-Fi audio components.
As shown, both tubes have been thoroughly tested on an advanced Amplitrex AT1000 tube testing system in full fixed-bias mode. Plate current (Ip) and mutual conductance (Gm) measurements alongside percentage performance ratings relative to nominal factory specs are detailed in the table below.
| Serial No. / Date Code | Triode Section | Plate Current (Ip) | Transconductance (Gm) | ||||
|---|---|---|---|---|---|---|---|
| Ref Spec | Result | % Ip | Ref Spec | Result | % Gm | ||
| SR.NO. 1545102 Date Code: B7A |
Triode 1 (T1) | 10.5 mA | 9.0 mA | 86% | 2200 µMhos | 1700 µMhos | 77% |
| Triode 2 (T2) | 10.5 mA | 7.8 mA | 74% | 2200 µMhos | 1500 µMhos | 68% | |
| SR.NO. 205014 Date Code: B7L |
Triode 1 (T1) | 10.5 mA | 7.0 mA | 67% | 2200 µMhos | 1700 µMhos | 77% |
| Triode 2 (T2) | 10.5 mA | 7.0 mA | 67% | 2200 µMhos | 1500 µMhos | 68% | |
Technical Note: Custom duties and taxes are the responsibility of the buyer in their country.
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