Will a Shiva fry a pair of Siemens EL 34s?

Discussion in 'Amps and Cabs' started by Shemp, Apr 22, 2005.

  1. Shemp

    Shemp Member

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    I have a couple of pair hanging around and I thought about popping a set in, but then I remembered someone once commenting that the Siemens were a tad sensitive to high plate voltages. How about an old set of Mullards?
     
  2. Hipster Dofus

    Hipster Dofus Member

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    I am no exspert, but I belive the Siemens to like a Lower Voltage. My Shiva has 500+ V on the Plates.
     
  3. tonedaddy

    tonedaddy Member

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    It's a little strange based on what Bogner's own manual says.

    From the Shiva manual:
    http://www.bogneramplification.com/ShivaManual.htm


    "3. Tubes

    EL34's should be only Svetlana or old stock Siemens/Telefunken/Mullard. Other brands may work but it's risky because of the high plate voltage we use."


    My understanding of the Siemens is that they shouldn't be used in amps with plate voltage over 450 volts. If the Shiva is higher than 450, I'd avoid the Siemens regardless of what the Bogner manual says.
     
  4. gizmo

    gizmo Guest

    I bought a few Siemens el-34s from mike @ KCA a few months ago for a Marshall and he cautioned me about high plate voltages with these. There must be something to it as Mike is generally well-regarded for his tube knowledge and advice.
     
  5. SQUAREHEAD

    SQUAREHEAD Supporting Member

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    When Reinhold forst started production of the Xtcy, he ALWAYS used Siemens 34's... for the first few years, until he could no longer get a good supply. They all (Ecstacys) run around the 500 mark. I've always used them in my Xtcy's and NEVER once had any problems.


    :confused:
     
  6. Ed DeGenaro

    Ed DeGenaro Supporting Member

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    I was gonna say i still use some Siemens 34s in my Plexi I pulled out of my old 100B.
     
  7. SQUAREHEAD

    SQUAREHEAD Supporting Member

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    Yep!!
    Great tubes, Ed!!
    I've never had one die in 20 years of using them in about everything I've ever owned.
    keith
     
  8. Ed DeGenaro

    Ed DeGenaro Supporting Member

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    I love 'em. Sheet...the ones in my plexi have been in that amp since about 5 years...and had already been in the 100B 2 years prior. :)
     
  9. ericb

    ericb Silver Supporting Member

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    Yep I"ve used Siemens in my Orange or120 head that runs about 500volts and never had a problem despite all the warnings I got!!

    eRIC
     
  10. SQUAREHEAD

    SQUAREHEAD Supporting Member

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    What's with all the warnings anyway?
    They seem fine in any amp I've ever used them in... :confused:
     
  11. tonedaddy

    tonedaddy Member

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    My understanding comes from Mike at KCA, and I assumed he was referring to RFT/Siemens.
     
  12. Blue Strat

    Blue Strat Member

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    I'm assuming that you haven't tried more than a handful of these tubes in your various amps. It's always possible to get lucky. Some tubes will beat the odds.

    Even if only 10 to 20% (which would be optimistic) would fail in amps with plate voltage over 450V, it would be pretty lame to recommend them for such applications knowing this fact.
     
  13. Shemp

    Shemp Member

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    Hi Mike

    Thanks for the reply. What do you recommend for the EL 34 Shiva?
     
  14. Blue Strat

    Blue Strat Member

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    SEDs, GT 6CA7GEs or Mullards (which are VERY pricey).
     
  15. hipfan

    hipfan Member

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    Mike - Speaking of the GT 6CA7GE's, I was wondering if you had any observations on properly biasing these tubes. Some resources I've seen say that they should be treated as EL34's for biasing purposes. Groove Tubes, however, (or at least Myles) says that they should be biased more like 6L6's or in between 6L6's and 6550's. This would result in a significantly warmer bias setting, if I'm doing the math correctly.

    I have a Rivera Fandango that I'm using them with, and it runs about 455 volts usually, for reference. Thanks for any insight!
     
  16. SQUAREHEAD

    SQUAREHEAD Supporting Member

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    Well...I guess I've been quite lucky. I have owned 5 Bogners in the last 14 years and every Marshall 100 watter I've owned/own has Siemens 34's in it, some of them are real old amps with plate voltage pushing 550...
    NEVER once have I EVER had one problem!

    Keith:)
     
  17. SQUAREHEAD

    SQUAREHEAD Supporting Member

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    Hey Mike,

    Why would Reinhold use that tube in all his amps if they were not safe over the 450 mark? (most Bogners are around 500)
    I do believe this "450" thing, not at all that I doubt you, as I've read it in many places... I just wonder why he would do that?

    Take care,
    Keith
     
  18. Mark Kane

    Mark Kane Silver Supporting Member

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    I've seen Seimens run forever at real high voltages and I've also seen three of them blow within a couple minutes at around 500 volts from personal experience. If they are gonna go they will go pretty quick. Bogner may be running 150k bias resistors between the PI and out put tubes or may have a high value screen resistors in his amps, both of which will help. They are nice sounding tubes but Mike K. is right about them.
     
  19. SQUAREHEAD

    SQUAREHEAD Supporting Member

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    Oh I believe him, Mark.
    I just don't understand why a guy like Bogner would use that specific tube (while he had a good supply) in ALL of his amps ... That's all. :confused:

    keith
     
  20. psychodave

    psychodave Senior Member

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    I used them in my 67 plexi SB with 560+ volts on the plates. They lasted 10 years and now I have a pair (from the 10 year old quad) in my JCM800 2204. :dude
     

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