Up for sale is a matched quad (4 pcs) of premium vintage NOS Valvo ECC81 / 12AT7 dual triode vacuum tubes, manufactured in Germany and supplied in individual white boxes. Celebrated worldwide for their precise European sonic signature, whisper-quiet operation, excellent dynamic range, and rich harmonic detail, these German-made tubes feature classic grey plates and top ring getter structures. A top-tier upgrade quad for high-end audio preamplifiers, phase inverters, driver stages, and guitar amplifiers requiring 12AT7 / ECC81 / 6201 series tubes.
All four 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: 10.0 mA / 5,500 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.1693003 | Triode 1 | 10.0 mA | 6.4 mA | 64% | 5500 | 5450 | 99% |
| Triode 2 | 10.0 mA | 6.8 mA | 68% | 5500 | 5640 | 103% | |
| SR.NO.1693005 | Triode 1 | 10.0 mA | 8.6 mA | 86% | 5500 | 5850 | 106% |
| Triode 2 | 10.0 mA | 9.0 mA | 90% | 5500 | 5960 | 108% | |
| SR.NO.1693008 | Triode 1 | 10.0 mA | 7.8 mA | 78% | 5500 | 5490 | 100% |
| Triode 2 | 10.0 mA | 8.2 mA | 82% | 5500 | 5900 | 107% | |
| SR.NO.1693011 | Triode 1 | 10.0 mA | 8.4 mA | 84% | 5500 | 5650 | 103% |
| Triode 2 | 10.0 mA | 9.0 mA | 90% | 5500 | 6210 | 113% | |
Technical Note: Custom duties and taxes are the responsibility of the buyer in their country.