Electro Harmonix 6550 Biasing ?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by jads57, Jul 13, 2008.

  1. jads57

    jads57 Supporting Member

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    What should these tubes be biased at. I have a Heriatge Colonial I`d like to try them in Thanks!
     
  2. RussB

    RussB low rent hobbyist Silver Supporting Member

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    60% to 65% dissipation
     
  3. RedRock

    RedRock Member

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    As to what attributed tube wattage rating? 25W? 30W?
     
  4. jads57

    jads57 Supporting Member

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    I have a bias adjustment in the back of my Heritage Colonial. Should it be 35ma or 50ma for example?
     
  5. RussB

    RussB low rent hobbyist Silver Supporting Member

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    What's the plate voltage?
     
  6. jads57

    jads57 Supporting Member

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  7. rockon1

    rockon1 Member

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    It depends on the plate voltage. For example - 35 watt tube divided by,say 425 plate voltage = 82 ma max X 60% = about 49 ma.for 60% idle dissapation. At 450 volts it would go down to about 47 ma and so on... Bob
     
  8. jads57

    jads57 Supporting Member

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    Thanks Bob, I`ll check out the plate voltage w/Paul C. who designed the amp.
     

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