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gemby 3rd June 2006 03:17 PM

Use of 12j1l and gu-50 tubes
I just got around 70 pcs of 12j1l ( ) tubes and around 20 of gu-50 tubes ( )

Most of them are naked, without alu shield, some still has shield, all NOS tubes...

I have 2 sockets for GU-50 and around 15 sockets for 12j1l tubes.....

I fount some schematics for GU-50, does anybody know some link or schematics for 12j1l tubes? Some preamp, driver?

gemby 3rd June 2006 03:36 PM

Here are photos of some of them :-)

arensattic 28th August 2008 06:28 AM

Schematics for 12J1L
Dear Gemby,

There are many schematics for 12J1L tubes on German and Russian websites. Using Babelfish, you can understand the accompanying text. Please note that the Cyriliic characters on Russian tubes are transcribed in different ways. Therefore, the 12J1L may also be called 12S1L, 12SH1L, 12Z1L or 12ZH1L (and the Russians may use their own Cyrillic letter).

For a first attempt, I would advise you to examine the following URLs carefully (with a search function):

(I can also send you scans if you indicate what you would like to see)

Note also that the 12J1L is a Russian equivalent of a German tube called RV12P2000. Schematics for this military tube (a "Wehrmachtröhre") will work when you replace it by the 12J1L.

I have myself performed some experiments with the 12J1L, both for RF and LF purposes. I like the tube since it is very quiet and non-microphonic. But I would not remove the aluminium screen for better looks - since the screen is an effective protection against mains-induced hum.

Hope this helps !

Best regards from the Netherlands,

Aren van Waarde

(aka arensattic)


soundbrigade 26th October 2008 11:15 AM

Aren: would GU50's work in your universal amplifier (the one with the EL156)? And use the GIT80 and POW80 transformers? (I am now considering monoblocks)

azazello 26th October 2008 05:17 PM
First tube - E 180F, plate curr./10-15ma/, or EF86 /15-20 ma/.
Second tube GU50, plate current 90 ma, bias - - 60-80 v.
Ra output transf. - 5 kom /Hammond 125FSE/.

Wavebourn 26th October 2008 06:06 PM


Originally posted by azazello
First tube - E 180F, plate curr./10-15ma/, or EF86 /15-20 ma/.
Second tube GU50, plate current 90 ma, bias - - 60-80 v.
Ra output transf. - 5 kom /Hammond 125FSE/.

No, EF80 and EF86 can't be used directly instead of 6J52P that is the last pentode developed for TV sets. Similar to E810F, but superior. It has 55 milliamperes per volt steepness.

Here is the info:

12J1L is completely different tube, a redesigned Telefunken RV12P2000 (GU-50 is also redesigned Telefunken tube, famous LS-50)

I would consider 12J1L as a very ordinary pentode, exceptions are long life and very high reliability. Since it was designed for aircraft vibrations it may have low microphonic perception, but I did not test them in such sensitive places.

azazello 26th October 2008 09:56 PM

Of course,EF80 and EF86 can't be used directly instead of 6J52P,
but Gemby can try to use its, or EF861, 6P15P, 6E5P or triods EC86, 6S3P, 6S4P.

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