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    St70 Output Tubes



    Posts : 33
    Join date : 2012-03-07

    St70 Output Tubes

    Post by rudes on Mon Apr 02, 2012 11:58 am

    Does anyone know if the EL34 tubes that have the words "Great Britian" on them are Mullard?


    Posts : 176
    Join date : 2010-03-07
    Age : 80
    Location : Houston Texas

    Re: St70 Output Tubes

    Post by stewdan on Tue Apr 03, 2012 1:47 pm

    Hi --

    50+ years ago, Mullard made tubes for both US Companies (like Sylvania/RCA/Zenith/Dynaco/Knight/Heath/Eico) and also Non-US Companies.

    If the Center Guide Pin has a hole in it, it "usually" is a Mullard Made Tube, but this is not always the case. There were some clones back in the 1970's and 1980's. If the glass has secondary codes identifying the plant OR THE DATE OF MANUFACTURE, it probably was made by Mullard.

    Some examples of Mullard Made EL34's that I have seen are:

    RCA Branded 6CA7/EL34's have a single getter on Top of the Glass Tube, hole in center pin and on the glass is etched "Made in Great Britain.

    Zenith Branded 6CA7/EL34's have a single getter on Top of the Glass Tube, hole in the center guide pin, and have both "GT Britain" and "Made in England" etched on the glass. Also date codes and plant codes. LOGOs are also possible.

    The Sylvania EL34's that I had were definitely made by Mullard.

    I have one odd-ball EL34 tube with twin getters on Top, a hole in the Center Pin, marked "Made in Great Britain" and the letters "DYN" barely visable on the glass. Mullard made Tubes for Dynaco back in the 1950s and 1960s.

    Maybe some of the others on the Forum can provide additional info.

    Good hunting,


    Posts : 33
    Join date : 2012-03-07

    Re: St70 Output Tubes

    Post by rudes on Tue Apr 03, 2012 3:14 pm

    Thanks for taking the time to reply!

    Posts : 14
    Join date : 2010-01-17
    Location : Coastal Virginia

    Re: St70 Output Tubes

    Post by captn on Tue Apr 03, 2012 4:05 pm


    These websites provide detailed info on most common audio tubes:

    Both offer detailed info and have pictures and videos which may help you identify your tubes. I have purchased tubes from both vendors and been very satisfied.


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    Re: St70 Output Tubes

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