Лампы: семейство ECC82 / 12AU7

[Serge44]

Краткий обзор семейства ECC82 / 12AU7

в скобках указывается, европейские или американские лампы

ECC82 (Europe) 12AU7 (USA)
Generic P/N. Next generation product after 6SL7

5814 (USA)
Special Quality ECC82. Different in two points: 1 )Long life. 2) improved grid isolation. Это очень редкие лампы.

12AU7W (USA) или 12AU7WA (USA)
Anything with "W" or WA is compliant with normal manufacturer specifications, and ADDITIONAL to military MIL-E-1/3D specifications. So it is no "different" tube, but it is better qualified, and has to pass some extra tests that military require. Test can be: Lifetime, shock resistance, hum. Meaningful test for anyone.

JAN тестированные типа JAN-12AUW (USA)
Much better than only "W" or "WA". Due to lack of understanding, JAN qualification is not so much valued as it should be. For me it is the IDEAL specification for anything that can not be 100% reliable by default, like tubes. What is done? To be qualified, you must set apart the whole lot, after production. From this lot, you must take a number of samples. (Sample quantity is in the JAN book). Suppose you have 10.000 tubes, then you must take 600 samples. All samples must undergo 1000 hours testing, under MAXIMUM power and MAXIMUM Temperature. So after 1000 hours you have: 9400 unused tubes, 600 used tubes, from which 80 are not good any more. With the official mathematical method you calculate the reliability of the NOT USED, 9400 tubes, under typical conditions. The formula uses specific factors for each products, that are found by evaluation. These factors are in the JAN handbook. The sample lot (600pcs) must be destroyed afterwards. This method is in use still for solid state devices. The lot gets a number, and the manufacturer keeps all documentation, for possible audits. Conclusion: Don't let stupid amateurs tell you anything else. Take your chance when you can buy these.

very close to ECC802S (Europe) 5963 (USA)
Special Quality ECC82. Different in two points: 1)Longer Stand by function 2) balanced tube by default. * With those two points you have basically the same properties as the Telefunken ECC802S. Это очень редкие лампы.

Close to ECC802S (Europe) 6189, 6189W (USA)
Special Quality ECC82. Different in five points: 1) Long Life 10k hours. 2) 500G shock. 3) filament isolation will stay "like new" always. 4)failure rate Max 0,15% per 1000hrs 5) tighter tolerances. Since 1...4 can not be checked when the tube is new, it is matter of trust in the manufacturer. So, ECC802S from top brands are very expensive. Because of point 3) this tube will have lower hum. Because the average user percepts this tube as something military, and not heard of it before, these tubes are stil not so expensive today. USA 6189W can be still be found from 1980's production. European ECC802S is very rare. Это очень редкие лампы.

ECC802S (Europe)
The undisputable top reference. Made by Telefunken and Tesla only.

E82CC (Europe)
Low noise, gold pin.

E82CC-SQ (Europe)
SQ=Special Quality, selected for low noise. Often with Gold pins. SQ is used by Philips and GE to indicate the tube has something special, and this measurable and specified. (See: 5814, 5963 and 6189)

[Serge44]

ECC82 NOS TUBES The NOS Supply Situation with ECC82 (12AU7) is generally not as good as with the ECC81. There is in Europe sometimes quantities popping up from military stocks, appearantly sold via the back door, but that is about it. There has been a hughe "last time buy" done by the American Army in the years 1986 and 1987 and from this stock are most of the NOS tubes that can be found in sealed 100pc master cartons, with barcode labels on the tube boxes. ECC82 as such is not found, but mostly the upgrade versions like 8514, 5963 and 6189. These are all ECC82/12AU7 with specifications above standard. Additional there was a lot of safety buying in the 1970's 1980's by armies of the former East European countries. These tubes are often RFT, Neuhaus and Tesla that come on the market now. However don't overestimate the artificial "good supply" of this tube. It is only artificial, and comes from clearing military stock rooms mostly in the east part of European. Once these stocks are all cleared (and it seems to be going that way pretty fast) prices for ECC82/12AU7 probably go up. No need to rush things, but on the other hand prices for ECC82 are attactive at the moment, so it is a good moment to buy still. A simliar example we had with the 12AX7 (ECC83). Two years ago, a reasonable stock of Philips ECG was found, and prices dumped quickly to 10€ for those. Everybody thought that was the new price. However these stocks are all gone, and now we are (back) at above 50€ for those.

[Yoshimo]

На фотографиях:
- слева: ECC82 производства Tungsram (Венгрия)
- справа: ECC82 производства RFT (ГДР)

[fxsound]

12AU7 Raytheon black plates, black glass, "D" getter , 1949