Max plate dissipation of power tubes

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by JimEff, Dec 20, 2009.

  1. JimEff

    JimEff Member

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    I've seen a lot of varying info regarding the max plate dissipation of power tubes and I wonder why there's not a standard, accurate, consistent list of these specs. Duncanamps.com lists the 6L6 max dissipation wattage as 23 watts. Another web site lists the same spec as 25 watts, yet another site lists it as 20 watts.

    How can I bias my amp accurately if I can't find consistent and accurate info? Does anyone know the REAL max dissipation wattages for the most popular guitar amp tubes? (6L6, 5881, EL34, 6V6...).

    This is the table listed at: http://www.duncanamps.com/technical/lvbias.html
    Is it correct?

    6V6 - 12 watts MAX
    6L6GC (and variants, like the 7581A) - 23 watts MAX
    5881 (American) - 18 watts MAX
    5881 (Russian) - 24 watts MAX
    EL34 - 20 watts MAX
    KT66 - 24 watts MAX
    6550 - 27 watts MAX
     
  2. SatelliteAmps

    SatelliteAmps Member

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    Some of those values are different depending on which tube manual you are looking at. When tube manuals publish information about tube performance, they are usually using a specific set of values (i.e. plate voltage) to determine wattage. Some do state design max performance, and then will go on to show examples that go over the design max. Most charted values are good enough for guitar amps to use as a guideline. How an amp gets biased should not be done purely out of max power, but out of max tone.
     
  3. Prairie Dawg

    Prairie Dawg Member

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    True. Some tubes are rated at absolute maximum value or design maximum value and others are rated at design center value. It's well worth knowing what this means and what scheme has been used to rate a given tube. Here's a couple tube sheets with the relevant clarification.

    http://www.classiccmp.org/rtellason/tubedata/12FR8.pdf
    http://tubedata.milbert.com/sheets/123/1/1BY2A.pdf
     
  4. JimEff

    JimEff Member

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    Wow, I'm converting over to solid state amps :rotflmao
     
  5. GT100

    GT100 Member

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    These numbers also only apply to the actual tubes for example a GE MADE (NOS) 6L6GE. The stuff comming out of Russia and China do not necessarly completely meet these specs. They are copies with varying levels of success....
     

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