Bogner Shiva has low Tube Bias.....what is the diff?

Discussion in 'Amps and Cabs' started by Ricker, Apr 25, 2008.

  1. Ricker

    Ricker Member

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    Hey all Biased Shiva heads....:)

    My Bogner seems to be biased on the cold side about 25mv........so my techie tells me.

    I see that most have it biased pretty hot ...38mv.
    Who has biased there shiva cold and hot ...what where your findings?
    What change could I expect in feel and tone if I went from 25mv to say 38mv?
    Don't want to send it back unneccesarilly but am finding the drive channel a bit woofy and loose bottom.
    Notes seem to go Fimm Fimm as opposed to Chim Chim.....know what I mean?

    Much thanks
    Rick
     
  2. sickboy79

    sickboy79 Member

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    I don't own a Shiva or know what the plate voltage it's running at but, in general a colder bias will yield a thinner, more sterile tone. If it's too cold, you'll run into that nasty crossover distortion. A hotter bias give a thicker tone, quicker power tube overdrive. If to hot - the tone will get a little ratty sounding, at least to my ears. It's all amp dependant to. There is really no right or wrong answer the "correct bias" as long as you're not too hot to redplate the tubes or to cold to get crossover distortion. It's up to your ear.
     
  3. Ricker

    Ricker Member

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    Thanks Bro

    I think it may be too cold and could do with some warming.
    Any others with experience wanna chime in.

    Thanks
    Rick
     
  4. freaksho

    freaksho Member

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    i have a 6L6 Shiva and i bias it at about 55% of max at idle. this is from stuff i read here and the Bogner Amp Forum. plus i called the Bogner shop and they suggested this range. i don't really know why but it's different from most amps (with which you typically shoot for about 60-70%).

    but don't take my word. i highly recommend you call Bogner. they are very happy to answer questions like this.

    edit:
    you also need higher rated tubes to get into the proper bias range. i described my xperience with this here.
     
  5. Ricker

    Ricker Member

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    Thanks Freaksho.

    I guess it's not really gonna make that of much of a difference if I go and bias it hotter?
    Did it make much difference to your sound....Tighter, Looser etc etc??

    I don't wanna send the amp back to be biased hotter for not much reason.
    Maybe when I re-tube again I will ask for the recommended Bias.

    Rick
     
  6. Giga

    Giga Member

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    Ricker: don't you have the Budda and the Koch anymore ?

    Giga.
     
  7. Ricker

    Ricker Member

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    Hey Man

    Yes I still have them......Got 2 Buddas sd80 and the sd18
    The Buddas are still my fave and first choice for gigs.

    Just trying to get the shiva as good as it can get cause I like the amp but I fight it alot.

    Cheers bro
    Rich
     

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